AD73422BB-40_技术文档

Dual Low Power CMOS

Analog Front End with DSP Microcomputer

a

AD73422

FUNCTIONAL BLOCK DIAGRAM

POWER-DOWN

FEATURES

AFE PERFORMANCE

Two 16-Bit A/D Converters

Two 16-Bit D/A Converters

Programmable Input/Output Sample Rates

78 dB ADC SNR

FULL MEMORY

MODE

CONTROL

DATA

MEMORY

PROGRAMMABLE

ADDRESS

EXTERNAL

ADDRESS

BUS

16K PM

(OPTIONAL (OPTIONAL

8K) 8K)

16K DM

PROGRAM

SEQUENCER

I/O

GENERATORS

AND

FLAGS

DAG 1 DAG 2

EXTERNAL

DATA

77 dB DAC SNR

64 kS/s Maximum Sample Rate

–90 dB Crosstalk

PROGRAM MEMORY ADDRESS

DATA MEMORY ADDRESS

BUS

BYTE DMA

CONTROLLER

Low Group Delay (25 ␮s Typ per ADC Channel,

50 ␮s Typ per DAC Channel)

Programmable Input/Output Gain

On-Chip Reference

PROGRAM MEMORY DATA

DATA MEMORY DATA

OR

EXTERNAL

DATA

BUS

ARITHMETIC UNITS

ALU MAC SHIFTER

SERIAL PORTS

TIMER

INTERNAL

DMA

PORT

SPORT 0 SPORT 1

DSP PERFORMANCE

19 ns Instruction Cycle Time @ 3.3 V, 52 MIPS

Sustained Performance

Single-Cycle Instruction Execution

Single-Cycle Context Switch

3-Bus Architecture Allows Dual Operand Fetches in

Every Instruction Cycle

ADSP-2100 BASE

ARCHITECTURE

HOST MODE

SERIAL PORT

SPORT 2

REF

ADC1

DAC1

ADC2

DAC2

ANALOG FRONT END

SECTION

Multifunction Instructions

Power-Down Mode Featuring Low CMOS Standby

Power Dissipation with 400 Cycle Recovery from

Power-Down Condition

applications. The A/D and D/A conversion channels feature

programmable input/output gains with ranges 38 dB and 21 dB

respectively. An on-chip reference voltage is included to allow

single supply operation.

Low Power Dissipation in Idle Mode

GENERAL DESCRIPTION

The AD73422 is a single device incorporating a dual analog

front end and a microcomputer optimized for digital signal

processing (DSP) and other high speed numeric processing

applications.

The sampling rate of the AFE is programmable with four sepa-

rate settings offering 64, 32, 16 and 8 kHz sampling rates (from

a master clock of 16.384 MHz), while the serial port (SPORT2)

allows easy expansion of the number of I/O channels by cascad-

ing extra AFEs external to the AD73422.

The AD73422’s analog front end (AFE) section features a dual

front-end converter for general purpose applications including

speech and telephony. The AFE section features two 16-bit A/D

conversion channels and two 16-bit D/A conversion channels.

Each channel provides 77 dB signal-to-noise ratio over a

voiceband signal bandwidth. It also features an input-to-output

gain network in both the analog and digital domains. This is

featured on both codecs and can be used for impedance match-

ing or scaling when interfacing to Subscriber Line Interface

Circuits (SLICs).

The AD73422’s DSP engine combines the ADSP-2100 family

base architecture (three computational units, data address gen-

erators and a program sequencer) with two serial ports, a 16-bit

internal DMA port, a byte DMA port, a programmable timer,

Flag I/O, extensive interrupt capabilities and on-chip program

and data memory.

The AD73422-80 integrates 80K bytes of on-chip memory

configured as 16K words (24-bit) of program RAM, and 16K

words (16-bit) of data RAM. The AD73422-40 integrates 40K

bytes of on-chip memory configured as 8K words (24-bit) of

program RAM, and 8K words (16-bit) of data RAM. Power-

down circuitry is also provided to meet the low power needs of

battery operated portable equipment. The AD73422 is available

in a 119-ball PBGA package.

The AD73422 is particularly suitable for a variety of applica-

tions in the speech and telephony area including low bit rate,

high quality compression, speech enhancement, recognition

and synthesis. The low group delay characteristic of the AFE

makes it suitable for single or multichannel active control

REV. 0

Information furnished by Analog Devices is believed to be accurate and

reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

Fax: 781/326-8703

World Wide Web Site: http://www.analog.com

(AVDD = DVDD = VDD = +3 V to 3.6 V; DGND = AGND = 0 V, f_DMCLK= 16.384 MHz,

_SAMP= 64 kHz; T_A= T_MINto T_MAX, unless otherwise noted.)

f

AD73422–SPECIFICATIONS

Parameter

Min Typ

Max

Units

Test Conditions

AFE SECTION

REFERENCE

REFCAP

Absolute Voltage, V_REFCAP

REFCAP TC

REFOUT

1.125 1.25

50

1.375

V

ppm/°C 0.1 µF Capacitor Required from

REFCAP to AGND2

Typical Output Impedance

Absolute Voltage, V_REFOUT

Minimum Load Resistance

Maximum Load Capacitance

130

1.08 1.2

1

Ω

1.32

100

V

Unloaded

kΩ

pF

INPUT AMPLIFIER

Offset

Maximum Output Swing

1.0

1.578

mV

V

Max Output Swing = (1.578/1.25) ×

V_REFCAP

Feedback Resistance

Feedback Capacitance

50

100

kΩ

pF

f_C= 32 kHz

ANALOG GAIN TAP

Gain at Maximum Setting

Gain at Minimum Setting

Gain Resolution

Gain Accuracy

Settling Time

+1

–1

5

1.0

0.5

Bits

%

ms

Gain Step Size = 0.0625

Output Unloaded

Tap Gain Change of –FS to +FS

Delay

ms

ADC SPECIFICATIONS

Maximum Input Range at VIN^{2, 3}

1.578

–2.85

1.0954

–6.02

V p-p

dBm

V p-p

dBm

Measured Differentially.

Max Input = (1.578/1.25) × V_REFCAP

Measured Differentially

Nominal Reference Level at VIN

(0 dBm0)

Absolute Gain

PGA = 0 dB

PGA = 38 dB

Gain Tracking Error

Signal to (Noise + Distortion)

PGA = 0 dB

–0.5 0.4

–0.7

+1.2

dB

1.0 kHz, 0 dBm0

1.0 kHz, +3 dBm0 to –50 dBm0

0.1

72

55

78

57

56

dB

300 Hz to 3400 Hz; f_SAMP= 64 kHz

300 Hz to 3400 Hz; f_SAMP= 8 kHz

0 Hz to f_SAMP/2; f_SAMP= 64 kHz

300 Hz to 3400 Hz; f_SAMP= 64 kHz

PGA = 38 dB

Total Harmonic Distortion

PGA = 0 dB

PGA = 38 dB

Intermodulation Distortion

Idle Channel Noise

Crosstalk, ADC-to-DAC

–84

–70

–65

–71

–100

–73

dB

dBm0

300 Hz to 3400 Hz; f_SAMP= 64 kHz

PGA = 0 dB

ADC Input Level: 1.0 kHz, 0 dBm0

DAC Input at Idle

dB

ADC-to-ADC

–100

–70

dB

ADC1 Input Level: 1.0 kHz, 0 dBm0

ADC2 Input at Idle. Input Amps Bypassed

Input Amplifiers Included in Input

Channel

DC Offset

Power Supply Rejection

–30

+10

–65

+45

mV

dB

PGA = 0 dB

Input Signal Level at AVDD and DVDD

Pins: 1.0 kHz, 100 mV p-p Sine Wave

Group Delay^{4, 5}

25

20

µs

kΩ

Input Resistance at PGA^{2, 4, 6}

DMCLK = 16.384 MHz; Input

Amplifiers Bypassed and AGT Off

DIGITAL GAIN TAP

Gain at Maximum Setting

Gain at Minimum Setting

Gain Resolution

+1

–1

16

Bits

ms

Tested to 5 MSBs of Settings

Includes DAC Delay

Delay

25

Settling Time

100

ms

Tap Gain Change from –FS to +FS;

Includes DAC Settling Time

–2–

REV. 0

AD73422

Parameter

Min Typ

Max

Units

Test Conditions

DAC SPECIFICATIONS

Maximum Voltage Output Swing²

Single-Ended

1.578

–2.85

3.156

3.17

V p-p

dBm

V p-p

dBm

PGA = 6 dB

Max Output = (1.578/1.25) × V_REFCAP

PGA = 6 dB

Differential

Max Output = 2 × ((1.578/1.25) × V_REFCAP

)

Nominal Voltage Output Swing (0 dBm0)

Single-Ended

1.0954

–6.02

2.1909

0

1.2

V p-p

dBm

V p-p

dBm

V

PGA = 6 dB

Differential

Output Bias Voltage

REFOUT Unloaded

Absolute Gain

Gain Tracking Error

–0.85 +0.4

0.1

+0.85 dB

dB

1.0 kHz, 0 dBm0; Unloaded

1.0 kHz, +3 dBm0 to –50 dBm0

Signal to (Noise + Distortion) at 0 dBm0

PGA = 6 dB

62.5 77

dB

300 Hz to 3400 Hz; f_SAMP= 64 kHz

Total Harmonic Distortion at 0 dBm0

PGA = 6 dB

Intermodulation Distortion

Idle Channel Noise

–80

–85

–90

–62.5

dB

dBm0

dB

300 Hz to 3400 Hz; f_SAMP= 64 kHz

PGA = 0 dB

Crosstalk, DAC-to-ADC

ADC Input Level: AGND;

DAC Output Level: 1.0 kHz, 0 dBm0;

Input Amplifiers Bypassed

–77

–100

dB

Input Amplifiers Included in Input Channel

DAC1 Output Level: AGND;

DAC2 Output Level: 1.0 kHz, 0 dBm0

Input Signal Level at AVDD and DVDD

Pins: 1.0 kHz, 100 mV p-p Sine Wave

Interpolator Bypassed

DAC-to-DAC

Power Supply Rejection

Group Delay^{4, 5}

–65

dB

25

50

+20

µs

Output DC Offset^{2, 7}

–20

+60

mV

2, 8

Minimum Load Resistance, R_L

Single-Ended⁴

Differential

600

Ω

2, 8

Maximum Load Capacitance, C_L

Single-Ended⁴

Differential

500

100

pF

LOGIC INPUTS

V_INH, Input High Voltage

DVDD – 0.8

DVDD V

V

_INL, Input Low Voltage

0

–10

0.8

+10

24

V

µA

pF

I_IH, Input Current

C_IN, Input Capacitance⁴

12

LOGIC OUTPUT

V

_OH, Output High Voltage

DVDD – 0.4

0

–10

DVDD V

|IOUT| ≤ 100 µA

V_OL, Output Low Voltage

Three-State Leakage Current

0.4

V

µA

+10

POWER SUPPLIES

AVDD

3.0

3.6

V

DVDD

10

I_DD

See Table I

NOTES

¹Operating temperature range is as follows: –20°C to +85°C; therefore, T_MIN= –20°C and T_MAX= +85°C.

²Test conditions: Input PGA set for 0 dB gain, Output PGA set for 6 dB gain, no load on analog outputs (unless otherwise noted).

³At input to sigma-delta modulator of ADC.

⁴Guaranteed by design.

⁵Overall group delay will be affected by the sample rate and the external digital filtering.

⁶The ADC’s input impedance is inversely proportional to DMCLK and is approximated by: (3.3 × 10¹¹)/DMCLK.

⁷Between VOUTP1 and VOUTN1 or between VOUTP2 and VOUTN2.

⁸At VOUT output.

⁹Frequency responses of ADC and DAC measured with input at audio reference level (the input level that produces an output level of –10 dBm0), with 38 dB pream-

plifier bypassed and input gain of 0 dB.

¹⁰Test Conditions: no load on digital inputs, analog inputs ac-coupled to ground, no load on analog outputs.

Specifications subject to change without notice.

REV. 0

–3–

(AVDD = DVDD = VDD = +3 V to 3.6 V; DGND = AGND = 0 V, f_DMCLK= 16.384 MHz,

_SAMP= 64 kHz; T_A= T_MINto T_MAX, unless otherwise noted.)

f

AD73422–SPECIFICATIONS

Parameter

Test Conditions

Min

Typ

Max

Units

DSP SECTION

V_IH

V_IL

Hi-Level Input Voltage^{1, 2}

Hi-Level CLKIN Voltage

Lo-Level Input Voltage^{1, 3}

Hi-Level Output Voltage^{1, 4, 5}

@ VDD = max

@ VDD = min

I_OH= –0.5 mA

@ VDD = min

I_OH= –100 µA⁶

@ VDD = min

I_OL= 2 mA

2.0

2.2

V

0.8

V_OH

2.4

V

V_DD– 0.3

V

V_OL

I_IH

Lo-Level Output Voltage^{1, 4, 5}

Hi-Level Input Current³

0.4

10

V

@ VDD = max

V_IN= VDD max

@ VDD = max

µA

I_IL

Lo-Level Input Current³

Three-State Leakage Current⁷

Supply Current (Idle)⁹

V

_IN= 0 V

I_OZH

I_OZL

I_DD

@ VDD = max

V_IN= VDD max⁸

@ VDD = max

V_IN= 0 V⁸

@ VDD = 3.6

t

_CK= 19 ns¹⁰

12

10

9

mA

t_CK= 25 ns¹⁰

_CK= 30 ns¹⁰

t

I_DD

Supply Current (Dynamic)¹¹

@ VDD = 3.6

T_AMB= +25°C

t

_CK= 19 ns¹⁰

_CK= 25 ns¹⁰

54

43

37

mA

t_CK= 30 ns¹⁰

C_I

Input Pin Capacitance^{3, 6, 12}

@ V_IN= 2.5 V

f

_IN= 1.0 MHz

T_AMB= +25°C

8

12

20

pF

C_O

Output Pin Capacitance^{6, 7, 12, 13}

@ V_IN= 2.5 V

f

_IN= 1.0 MHz

T_AMB= +25°C

10

NOTES

¹Bidirectional pins: D0–D23, RFS0, RFS1, SCLK0, SCLK1, TFS0, TFS1, A1–A13, PF0–PF7.

²Input only pins: RESET, BR, DR0, DR1, PWD.

³Input only pins: CLKIN, RESET, BR, DR0, DR1, PWD.

⁴Output pins: BG, PMS, DMS, BMS, IOMS, CMS, RD, WR, PWDACK, A0, DT0, DT1, CLKOUT, FL2–0, BGH.

⁵Although specified for TTL outputs, all AD73422 outputs are CMOS-compatible and will drive to VDD and GND, assuming no dc loads.

⁶Guaranteed but not tested.

⁷Three-statable pins: A0–A13, D0–D23, PMS, DMS, BMS, IOMS, CMS, RD, WR, DT0, DT1, SCLK0, SCLK1, TFS0, TFS1, RFS0, RFS1, PF0–PF7.

⁸0 V on BR.

⁹Idle refers to AD73422 state of operation during execution of IDLE instruction. Deasserted pins are driven to either VDD or GND.

10

11

V

I

= 0 V and 3 V. For typical figures for supply currents, refer to Power Dissipation section.

measurement taken with all instructions executing from internal memory. 50% of the instructions are multifunction (types 1, 4, 5, 12, 13, 14), 30% are type 2

IN

DD

and type 6, and 20% are idle instructions.

¹²Applies to PBGA package type.

¹³Output pin capacitance is the capacitive load for any three-stated output pin.

Specifications subject to change without notice.

–4–

REV. 0

AD73422

POWER CONSUMPTION

Conditions

Typ

Max

SE

AMCLK On

Test Conditions

AFE SECTION

ADCs Only On

11.5

20

24.5

12

22

27

1

YES

REFOUT Disabled

DACs Only On

ADCs and DACs On

ADCs and DACs

and Input Amps On

ADCs and DACs

and AGT On

All Sections On

REFCAP Only On

REFCAP and

30

34

1

YES

REFOUT Disabled

29

37

0.8

32.5

43.5

1.25

1

0

YES

NO

REFOUT Only On

All AFE Sections Off

3.5

1.5

10 µA

4.75

3.0

40 µA

0

NO

YES

NO

AMCLK Active Levels Equal to 0 V and DVDD

Digital Inputs Static and Equal to 0 V or DVDD

NOTES

The above values are in mA and are typical values unless otherwise noted.

Specifications subject to change without notice.

TIMING CHARACTERISTICS–AFE SECTION¹

Parameter

Limit

Units

Description

Clock Signals

See Figure 1

t₁

t₂

t₃

61

24.4

ns min

16.384 MHz AMCLK Period

AMCLK Width High

AMCLK Width Low

Serial Port

See Figures 3 and 4

t₄

t₅

t₆

t₇

t₈

t₉

t₁₀

t₁₁

t₁₂

t₁₃

t₁

ns min

ns max

ns min

ns max

SCLK Period (SCLK = AMCLK)

SCLK Width High

SCLK Width Low

SDI/SDIFS Setup Before SCLK Low

SDI/SDIFS Hold After SCLK Low

SDOFS Delay from SCLK High

SDOFS Hold After SCLK High

SDO Hold After SCLK High

SDO Delay from SCLK High

SCLK Delay from AMCLK

0.4 × t₁

20

0

10

30

NOTES

¹For details of the DSP section timing, please refer to the ADSP-2185L data sheet and the ADSP-2100 Family User’s Manual, Third Edition.

Specifications subject to change without notice.

REV. 0

–5–

AD73422

ABSOLUTE MAXIMUM RATINGS*

Reflow Soldering

(T_A= +25°C unless otherwise noted)

Maximum Temperature . . . . . . . . . . . . . . . . . . . . . . +225°C

Time at Maximum Temperature . . . . . . . . . . . . . . . . . 15 sec

Maximum Temperature Ramp Rate . . . . . . . . . . . . 1.3°C/sec

*Stresses above those listed under Absolute Maximum Ratings may cause perma-

nent damage to the device. This is a stress rating only; functional operation of the

device at these or any other conditions above those listed in the operational

sections of this specification is not implied. Exposure to absolute maximum rating

conditions for extended periods may affect device reliability.

AVDD, DVDD to GND . . . . . . . . . . . . . . . . –0.3 V to +4.6 V

AGND to DGND . . . . . . . . . . . . . . . . . . . . . –0.3 V to +0.3 V

Digital I/O Voltage to DGND . . . . . –0.3 V to DVDD + 0.3 V

Analog I/O Voltage to AGND . . . . . –0.3 V to AVDD + 0.3 V

Operating Temperature Range

Industrial (B Version) . . . . . . . . . . . . . . . . –20°C to +85°C

Storage Temperature Range . . . . . . . . . . . . –40°C to +125°C

Maximum Junction Temperature . . . . . . . . . . . . . . . . +150°C

PBGA, θ_JAThermal Impedance . . . . . . . . . . . . . . . . . 25°C/W

CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily

accumulate on the human body and test equipment and can discharge without detection.

Although the AD73422 features proprietary ESD protection circuitry, permanent damage may

occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD

precautions are recommended to avoid performance degradation or loss of functionality.

WARNING!

ESD SENSITIVE DEVICE

ORDERING GUIDE

Temperature

Range

Package

Description

Package

Option

Model

AD73422BB-80

AD73422BB-40

EVAL-AD73422EB

–20°C to +85°C

119-Ball Plastic Ball Grid Array

Evaluation Board

B-119

PBGA BALL CONFIGURATION

2

3

VDD (INT)

WR

5

6

7

1

4

A

DMS

CLKIN

A11/IAD10

A12/IAD11

A13/IAD12

GND

A7/IAD6

A8/IAD7

A9/IAD8

A10/IAD9

A4/IAD3

A5/IAD4

GND

IRQE/PF4

B

C

D

E

F

IRQL0/PF5

IRQL1/PF6

IRQ2/PF7

PMS

IOMS

CMS

XTAL

RD

VDD (EXT)

CLKOUT

BMS

A6/IAD5

DT0

DR0

TFS0

SCLK0

RFS0

DT1/F0

DR1/FI

RESET

ECLK

A3/IAD2

PWDACK

GND

A2/IAD1

BGH

A1/IAD0

A0

MODE A/PF0 MODE B/PF1

VDD (EXT) MODE C/PF2

G

H

J

TFS1/IRQ1

SCLK1

EMS

RFS1/IRQ0

ERESET

EE

PWD

PF3

FL0

FL1

D21

FL2

D20

D23

D22

K

L

ELOUT

BG

ELIN

EINT

D5/IAL

D4/IS

D19

D18

D17

D16

D3/IACK

D2/IAD15

D1/IAD14

D0/IAD13

SDOFS

D8

D9

D12

D15

EBG

D7/IWR

D6/IRD

DGND

SDI

VDD (EXT)

GND

D11

D14

M

N

P

R

T

BR

VDD (INT)

DVDD

D10

D13

ARESET

SE

EBR

SCLK2

REFCAP

VINN2

VOUTN1

AMCLK

REFOUT

VFBP2

VINP2

SDO

SDIFS

VFBN1

VOUTP2

VINN1

VOUTN2

TOP VIEW

VFBN2

VOUTP1

VFBP1

AGND

VINP1

AVDD

U

NOTES:

VDD (INT) – DSP CORE SUPPLY

VDD (EXT) – DSP I/O DRIVER SUPPLY

BOTH VDD (INT) AND VDD (EXT) SHOULD BE POWERED FROM THE SAME SUPPLY.

–6–

REV. 0

AD73422

PBGA BALL CONFIGURATION DESCRIPTIONS

BGA

Location

Mnemonic

Function

VINP1

VFBP1

T2

T1

Analog Input to the inverting terminal of the inverting input amplifier on Channel 1’s Positive Input.

Feedback connection from the output of the inverting amplifier on Channel 1’s positive input. When the input

amplifiers are bypassed, this pin allows direct access to the positive input of Channel 1’s sigma-delta modulator.

Analog Input to the inverting terminal of the inverting input amplifier on Channel 1’s Negative Input.

Feedback connection from the output of the inverting amplifier on Channel 1’s positive input. When the input

amplifiers are bypassed, this pin allows direct access to the negative input of Channel 1’s sigma-delta modulator.

Buffered Reference Output, which has a nominal value of 1.2 V. As the reference is common to the two

codec units, the reference value is set by the wired OR of the CRC:7 bits in each codec’s status register.

A Bypass Capacitor to AGND2 of 0.1 µF is required for the on-chip reference. The capacitor should be

fixed to this pin.

VINN1

VFBN1

T4

T3

REFOUT

REFCAP

R7

R6

DGND

DVDD

ARESET

P4

P3

P5

AFE Digital Ground/Substrate Connection.

AFE Digital Power Supply Connection.

Active Low Reset Signal. This input resets the entire chip, resetting the control registers and clearing the

digital circuitry.

SCLK2

P6

Output Serial Clock whose rate determines the serial transfer rate to/from the codec. It is used to clock data

or control information to and from the serial port (SPORT). The frequency of SCLK is equal to the fre-

quency of the master clock (AMCLK) divided by an integer number—this integer number being the prod-

uct of the external master clock rate divider and the serial clock rate divider.

AFE Master Clock Input. AMCLK is driven from an external clock signal. If it is required to run the DSP

and AFE sections from a common clock crystal, AMCLK should be connected to the XTAL pin of the

DSP section.

AMCLK

P7

SDO

R1

R2

Serial Data Output of the Codec. Both data and control information may be output on this pin and is clocked on

the positive edge of SCLK. SDO is in three-state when no information is being transmitted and when SE is low.

Framing Signal Output for SDO Serial Transfers. The frame sync is one bit wide and is active one SCLK

period before the first bit (MSB) of each output word. SDOFS is referenced to the positive edge of SCLK.

SDOFS is in three-state when SE is low.

SDOFS

SDIFS

R3

Framing Signal Input for SDI Serial Transfers. The frame sync is one bit wide and is valid one SCLK pe-

riod before the first bit (MSB) of each input word. SDIFS is sampled on the negative edge of SCLK and is

ignored when SE is low.

SDI

SE

R4

R5

Serial Data Input of the Codec. Both data and control information may be input on this pin and are clocked

on the negative edge of SCLK. SDI is ignored when SE is low.

SPORT Enable. Asynchronous input enable pin for the SPORT. When SE is set low by the DSP, the out-

put pins of the SPORT are three-stated and the input pins are ignored. SCLK is also disabled internally in

order to decrease power dissipation. When SE is brought high, the control and data registers of the SPORT

are at their original values (before SE was brought low), however the timing counters and other internal

registers are at their reset values.

AGND

AVDD

VOUTP2

VOUTN2

VOUTP1

VOUTN1

VINP2

U1

U2

U3

U4

U5

U6

U7

T7

AFE Analog Ground/Substrate Connection.

AFE Analog Power Supply Connection.

Analog Output from the Positive Terminal of Output Channel 2.

Analog Output from the Negative Terminal of Output Channel 2.

Analog Output from the Positive Terminal of Output Channel 1.

Analog Output from the Negative Terminal of Output Channel 1.

Analog Input to the inverting terminal of the inverting input amplifier on Channel 2’s Positive Input.

Feedback connection from the output of the inverting amplifier on Channel 2’s positive input. When the input

amplifiers are bypassed, this pin allows direct access to the positive input of Channel 2’s sigma-delta modulator.

Analog Input to the inverting terminal of the inverting input amplifier on Channel 2’s Negative Input.

Feedback connection from the output of the inverting amplifier on Channel 2’s Negative Input. When the input

amplifiers are bypassed, this pin allows direct access to the negative input of Channel 2’s sigma-delta modulator.

(Input) Processor Reset Input.

(Input) Bus Request Input.

(Output) Bus Grant Output.

(Output) Bus Grant Hung Output.

(Output) Data Memory Select Output.

VFBP2

VINN2

VFBN2

T6

T5

RESET

BR

BG

BGH

DMS

H3

N1

L1

F5

A2

PMS

IOMS

BMS

B2

C2

D3

(Output) Program Memory Select Output.

(Output) Memory Select Output.

(Output) Byte Memory Select Output.

CMS

RD

WR

IRQ2/

PF7

IRQL1/

PF6

D2

C3

B3

(Output) Combined Memory Select Output.

(Output) Memory Read Enable Output.

(Output) Memory Write Enable Output.

(Input) Edge- or Level-Sensitive Interrupt Request¹.

(Input/Output) Programmable I/O Pin.

(Input) Level-Sensitive Interrupt Requests¹.

(Input/Output) Programmable I/O Pin.

D1

C1

REV. 0

–7–

AD73422

PBGA BALL CONFIGURATION DESCRIPTIONS (Continued)

BGA

Location

Mnemonic

Function

IRQL0/

PF5

IRQE/

PF4

(Input) Level-Sensitive Interrupt Requests¹.

B1

(Input/Output) Programmable I/O Pin.

(Input) Edge-Sensitive Interrupt Requests¹.

A1

(Input/Output) Programmable I/O Pin.

PF3

Mode C/

PF2

Mode B/

PF1

Mode A/

PF0

CLKIN

XTAL

CLKOUT

SPORT0

TFS0

RFS0

DT0

H4

(Input/Output) Programmable I/O Pin During Normal Operation.

(Input) Mode Select Input—Checked Only During RESET.

(Input/Output) Programmable I/O Pin During Normal Operation.

(Input) Mode Select Input—Checked Only During RESET.

(Input/Output) Programmable I/O Pin During Normal Operation.

(Input) Mode Select Input—Checked Only During RESET.

(Input/Output) Programmable I/O Pin During Normal Operation.

(Inputs) Clock or Quartz Crystal Input. The CLKIN input cannot be halted or changed during operation

nor operated below 10 MHz during normal operation.

(Output) Processor Clock Output.

G7

F7

F6

A4

B4

D4

E2

E3

E1

F1

F2

(Input/Output) SPORT0 Transmit Frame Sync.

(Input/Output) SPORT0 Receive Frame Sync.

(Output) SPORT0 Transmit Data.

(Input) SPORT0 Receive Data.

(Input/Output) SPORT0 Serial Clock.

DR0

SCLK0

SPORT1

TFS1/

IRQ1

RFS1

IRQ0

(Input/Output) SPORT1 Transmit Frame Sync.

(Input) Edge or Level Sensitive Interrupt.

(Input/Output) SPORT1 Receive Frame Sync.

(Input) Edge or Level Sensitive Interrupt.

(Output) SPORT1 Transmit Data.

(Output) Flag Out².

G1

G2

F3

DT1/

FO

DR1/

FI

SCLK1

FL0

FL1

FL2

VDD(INT)

(Input) SPORT1 Receive Data.

G3

H1

H5

H6

H7

A3

N3

C4

G6

M5

C7

D5

G4

N5

(Input) Flag In².

(Input/Output) SPORT1 Serial Clock.

(Output) Flag 0.

(Output) Flag 1.

(Output) Flag 2.

(Input) DSP Core Supply.

VDD(EXT)

GND

(Input) DSP I/O Interface Supply.

DSP Ground.

EZ-ICE Port

ERESET

EMS

H2

J1

J2

EE

ECLK

ELOUT

ELIN

EINT

EBR

J3

K1

K2

K3

P1

M1

EBG

A

ddress Bus

A0–E7; A1/IAD0–E6; A2/IAD1–E5; A3/IAD2–E4; A4/IAD3–A7; A5/IAD4–B7; A6/IAD5–D7; A7/IAD6–A6;

A8/IAD7–B6; A9/IAD8–C6; A10/IAD9–D6; A11/IAD10–A5; A12/IAD11–B5; A13/IAD12–C5

D0/IAD13–P2; D1/IAD14–N2; D2/IAD15–M2; D3/IACK–L2; D4/IS–M3; D5/IAL–L3; D6/IRD–N4; D7/IWR–

M4; D8–L4; D9–L5; D10–N6; D11–M6; D12–L6; D13–N7; D14–M7; D15–L7; D16–K7; D17–K6; D18–K5;

D19–K4; D20–J7; D21–J6; D22–J5; D23–J4

Data Bus

NOTES

¹Interrupt/Flag pins retain both functions concurrently. If IMASK is set to enable the corresponding interrupts, then the DSP will vector to the appropriate interrupt

vector address when the pin is asserted, either by external devices, or set as a programmable flag.

²SPORT configuration determined by the DSP System Control Register. Software configurable.

–8–

REV. 0

AD73422

ARCHITECTURE OVERVIEW

two data buses (PMD and DMD) share a single external data

bus. Byte memory space and I/O memory space also share the

external buses.

The AD73422 instruction set provides flexible data moves and

multifunction (one or two data moves with a computation)

instructions. Every instruction can be executed in a single pro-

cessor cycle. The AD73422 assembly language uses an algebraic

syntax for ease of coding and readability. A comprehensive set

of development tools supports program development.

An interface to low cost byte-wide memory is provided by the

Byte DMA port (BDMA port). The BDMA port is bidirectional

and can directly address up to four megabytes of external RAM

or ROM for off-chip storage of program overlays or data tables.

POWER-DOWN

The AD73422 can respond to eleven interrupts. There can be

up to six external interrupts (one edge-sensitive, two level-

sensitive and three configurable) and seven internal interrupts

generated by the timer, the serial ports (SPORTs), the Byte

DMA port and the power-down circuitry. There is also a master

RESET signal. The two serial ports provide a complete synchro-

nous serial interface with optional companding in hardware and

a wide variety of framed or frameless data transmit and receive

modes of operation.

FULL MEMORY

MODE

CONTROL

DATA

MEMORY

PROGRAMMABLE

ADDRESS

EXTERNAL

ADDRESS

BUS

16K PM

(OPTIONAL (OPTIONAL

8K) 8K)

16K DM

PROGRAM

SEQUENCER

I/O

GENERATORS

AND

FLAGS

DAG 1 DAG 2

EXTERNAL

DATA

BUS

PROGRAM MEMORY ADDRESS

DATA MEMORY ADDRESS

BYTE DMA

CONTROLLER

PROGRAM MEMORY DATA

DATA MEMORY DATA

OR

EXTERNAL

DATA

BUS

Each port can generate an internal programmable serial clock or

accept an external serial clock.

ARITHMETIC UNITS

ALU MAC SHIFTER

SERIAL PORTS

TIMER

INTERNAL

DMA

PORT

SPORT 0 SPORT 1

ADSP-2100 BASE

ARCHITECTURE

The AD73422 provides up to 13 general-purpose flag pins. The

data input and output pins on SPORT1 can be alternatively

configured as an input flag and an output flag. In addition, eight

flags are programmable as inputs or outputs and three flags are

always outputs.

HOST MODE

SERIAL PORT

SPORT 2

REF

ADC1

DAC1

ADC2

DAC2

A programmable interval timer generates periodic interrupts. A

16-bit count register (TCOUNT) is decremented every n pro-

cessor cycle, where n is a scaling value stored in an 8-bit register

(TSCALE). When the value of the count register reaches zero,

an interrupt is generated and the count register is reloaded from

a 16-bit period register (TPERIOD).

ANALOG FRONT END

SECTION

Figure 1. Functional Block Diagram

Figure 1 is an overall block diagram of the AD73422. The pro-

cessor section contains three independent computational units:

the ALU, the multiplier/accumulator (MAC) and the shifter.

The computational units process 16-bit data directly and have

provisions to support multiprecision computations. The ALU

performs a standard set of arithmetic and logic operations; divi-

sion primitives are also supported. The MAC performs single-

cycle multiply, multiply/add and multiply/subtract operations

with 40 bits of accumulation. The shifter performs logical and

arithmetic shifts, normalization, denormalization and derive

exponent operations.

Analog Front End

The AFE section is configured as a separate block that is nor-

mally connected to either SPORT0 or SPORT1 of the DSP

section. As it is not hardwired to either SPORT, the user has

total flexibility in how they wish to allocate system resources to

support the AFE. It is also possible to further expand the num-

ber of analog I/O channels connected to the SPORT by cascad-

ing other single or dual channel AFEs (AD73311 or AD73322)

external to the AD73422.

The internal result (R) bus connects the computational units so

that the output of any unit may be the input of any unit on the

next cycle.

The AFE is configured as a cascade of two I/O channels (similar

to that of the discrete AD73322—refer to the AD73322 data sheet

for more details), with each channel having a separate 16-bit

sigma-delta based ADC and DAC. Both channels share a com-

mon reference whose nominal value is 1.2 V. Figure 2 shows a

block diagram of the AFE section of the AD73422. It shows two

channels of ADC and DAC conversion, along with a common

reference. Communication to both channels is handled by the

SPORT2 block which interfaces to either SPORT0 or SPORT1 of

the DSP section.

A powerful program sequencer and two dedicated data address

generators ensure efficient delivery of operands to these compu-

tational units. The sequencer supports conditional jumps, sub-

routine calls and returns in a single cycle. With internal loop

counters and loop stacks, the AD73422 executes looped code

with zero overhead; no explicit jump instructions are required to

maintain loops.

Two data address generators (DAGs) provide addresses for

simultaneous dual operand fetches (from data memory and

program memory). Each DAG maintains and updates four

address pointers. Whenever the pointer is used to access data

(indirect addressing), it is post-modified by the value of one of

four possible modify registers. A length value may be associated

with each pointer to implement automatic modulo addressing

for circular buffers.

Figure 3 shows the analog connectivity available on each chan-

nel of the AFE (Channel 1 is detailed here). Both channels

feature fully differential inputs and outputs. The input section

allows direct connection to the internal Programmable Gain

Amplifier at the input of the sigma-delta ADC section, or op-

tional inverting amplifiers may be configured to provide some

fixed external gain or to interface to a transducer with relatively

high source impedance. The input section also features pro-

grammable differential channel inversion and configuration of

the differential input as two separate single-ended inputs. The

ADC features a second order sigma-delta modulator which

The two address buses (PMA and DMA) share a single external

address bus, allowing memory to be expanded off-chip, and the

REV. 0

–9–

AD73422

VFBN1

VINN1

ANALOG

SIGMA-DELTA

MODULATOR

INVERT

SINGLE-ENDED

ENABLE

ANALOG

LOOP-

BACK

0/38dB

PGA

V

DECIMATOR

REF

SDI

VINP1

VFBP1

SDIFS

SCLK2

GAIN

1

GAIN

1

VOUTP1

VOUTN1

DIGITAL

SIGMA-

CONTINUOUS

TIME

LOW-PASS

FILTER

SWITCHED

CAPACITOR

LOW-PASS

FILTER

INTER-

POLATOR

1-BIT

DAC

+6/–15dB

PGA

DELTA

MODULATOR

SERIAL

I/O

PORT

REFERENCE

REFCAP

REFOUT

AD73422

AFE SECTION

ARESET

AMCLK

SE

VFBN2

VINN2

ANALOG

SIGMA-DELTA

MODULATOR

INVERT

SINGLE-ENDED

ENABLE

ANALOG

LOOP-

BACK

0/38dB

PGA

V

DECIMATOR

REF

VINP2

VFBP2

GAIN

1

GAIN

1

SDO

SDOFS

DIGITAL

SIGMA-

VOUTP2

VOUTN2

CONTINUOUS

TIME

LOW-PASS

FILTER

SWITCHED

CAPACITOR

LOW-PASS

FILTER

INTER-

POLATOR

1-BIT

DAC

+6/–15dB

PGA

DELTA

MODULATOR

Figure 2. Functional Block Diagram of Analog Front End Section

samples at DMCLK/8. Its bitstream output is filtered and deci-

mated by a Sinc-cubed decimator to provide a sample rate se-

lectable from 64 kHz, 32 kHz, 16 kHz or 8 kHz (based on an

AMCLK of 16.384 MHz).

Each channel also features two programmable gain elements,

Analog Gain Tap (AGT) and Digital Gain Tap (DGT), which,

when enabled, add a signed and scaled amount of the input

signal to the DAC’s output signal. This is of particular use in

line impedance balancing when interfacing the AFE to Sub-

scriber Line Interface Circuits (SLICs).

ANALOG

LOOP-BACK

SELECT

SINGLE-ENDED

ENABLE

INVERTING

OP AMPS

INVERT

FUNCTIONAL DESCRIPTION - AFE

Encoder Channels

VFBN1

VINN1

Both encoder channels consist of a pair of inverting op amps

with feedback connections that can be bypassed if required, a

switched capacitor PGA and a sigma-delta analog-to-digital

converter (ADC). An on-board digital filter, which forms part

of the sigma-delta ADC, also performs critical system-level

filtering. Due to the high level of oversampling, the input anti-

alias requirements are reduced such that a simple single-pole

RC stage is sufficient to give adequate attenuation in the band

of interest.

V

REF

0/38dB

PGA

VINP1

VFBP1

GAIN

1

V

REF

ANALOG

GAIN TAP

VOUTP1

VOUTN1

CONTINUOUS

TIME

+6/–15dB

PGA

LOW-PASS

FILTER

Programmable Gain Amplifier

Each encoder section’s analog front end comprises a switched

capacitor PGA which also forms part of the sigma-delta modu-

lator. The SC sampling frequency is DMCLK/8. The PGA,

whose programmable gain settings are shown in Table I, may be

used to increase the signal level applied to the ADC from low

output sources such as microphones, and can be used to avoid

placing external amplifiers in the circuit. The input signal level

to the sigma-delta modulator should not exceed the maximum

input voltage permitted.

AD73422

REFOUT

REFCAP

REFERENCE

AFE SECTION

Figure 3. Analog Front End Configuration

The DAC channel features a Sinc-cubed interpolator which

increases the sample rate from the selected rate to the digital

sigma-delta modulator rate of DMCLK/8. The digital sigma-

delta modulator’s output bitstream is fed to a single-bit DAC

whose output is reconstructed/filtered by two stages of low-pass

filtering (switched capacitor and continuous time) before being

applied to the differential output driver.

The PGA gain is set by bits IGS0, IGS1 and IGS2 (CRD:0–2)

in control register D.

–10–

REV. 0

AD73422

Table I. PGA Settings for the Encoder Channel

of these techniques, followed by the application of a digital

filter, sufficiently reduces the noise in band to ensure good

dynamic performance from the part (Figure 4c).

IGS2

IGS1

IGS0

Gain (dB)

0

1

0

1

0

1

0

1

0

1

0

1

0

1

0

6

Figure 5 shows the various stages of filtering that are employed

in a typical AD73422 application. In Figure 5a we see the trans-

fer function of the external analog antialias filter. Even though it

is a single RC pole, its cutoff frequency is sufficiently far away

from the initial sampling frequency (DMCLK/8) that it takes

care of any signals that could be aliased by the sampling fre-

quency. This also shows the major difference between the initial

oversampling rate and the bandwidth of interest. In Figure 5b,

the signal and noise-shaping responses of the sigma-delta modu-

lator are shown. The signal response provides further rejection

of any high frequency signals, while the noise-shaping will push

the inherent quantization noise to an out-of-band position. The

detail of Figure 5c shows the response of the digital decima-

tion filter (Sinc-cubed response) with nulls every multiple of

DMCLK/256, which corresponds to the decimation filter up-

date rate for a 64 kHz sampling. The nulls of the Sinc3 response

correspond with multiples of the chosen sampling frequency.

The final detail in Figure 5d shows the application of a final

antialias filter in the DSP engine. This has the advantage of

being implemented according to the user’s requirements and

available MIPS. The filtering in Figures 5a through 5c is imple-

mented in the AD73422.

12

18

20

26

32

38

ADC

Both ADCs consist of an analog sigma-delta modulator and a

digital antialiasing decimation filter. The sigma-delta modu-

lator noise-shapes the signal and produces 1-bit samples at a

DMCLK/8 rate. This bitstream, representing the analog input

signal, is input to the antialiasing decimation filter. The decima-

tion filter reduces the sample rate and increases the resolution.

Analog Sigma-Delta Modulator

The AD73422’s input channels employ a sigma-delta conver-

sion technique, which provides a high resolution 16-bit output

with system filtering being implemented on-chip.

Sigma-delta converters employ a technique known as over-

sampling where the sampling rate is many times the highest

frequency of interest. In the case of the AD73422, the initial

sampling rate of the sigma-delta modulator is DMCLK/8. The

main effect of oversampling is that the quantization noise is

spread over a very wide bandwidth, up to F_S/2 = DMCLK/16

(Figure 4a). This means that the noise in the band of interest is

much reduced. Another complementary feature of sigma-delta

converters is the use of a technique called noise-shaping. This

technique has the effect of pushing the noise from the band of

interest to an out-of-band position (Figure 4b). The combination

F

= 4kHz

F

= DMCLK/8

B

SINIT

a. Analog Antialias Filter Transfer Function

SIGNAL TRANSFER FUNCTION

NOISE TRANSFER FUNCTION

BAND

F

/2

S

OF

F

= 4kHz

F

= DMCLK/8

B

SINIT

DMCLK/16

INTEREST

a.

b.

b. Analog Sigma-Delta Modulator Transfer Function

NOISE-SHAPING

BAND

OF

INTEREST

F

/2

S

DMCLK/16

F

= 4kHz

F

= DMCLK/256

B

SINTER

c. Digital Decimator Transfer Function

DIGITAL FILTER

BAND

OF

INTEREST

F

/2

S

DMCLK/16

c.

F

= 4kHz

F

= 8kHz

F

= DMCLK/256

SFINAL

B

SINTER

Figure 4. Sigma-Delta Noise Reduction

d. Final Filter LPF (HPF) Transfer Function

Figure 5. ADC Frequency Responses

REV. 0

–11–

AD73422

Decimation Filter

the output word is set at 0x7FFF, which has the LSB set to 1.

In mixed Control/Data Mode, the resolution is fixed at 15 bits,

with the MSB of the 16-bit transfer being used as a flag bit to

indicate either control or data in the frame.

The digital filter used in the AD73422’s AFE section carries out

two important functions. Firstly, it removes the out-of-band

quantization noise, which is shaped by the analog modulator,

and secondly, it decimates the high frequency bitstream to a

lower rate 16-bit word.

Decoder Channel

The decoder channels consist of digital interpolators, digital

sigma-delta modulators, single bit digital-to-analog converters

(DAC), analog smoothing filters and programmable gain ampli-

fiers with differential outputs.

The antialiasing decimation filter is a sinc-cubed digital filter

that reduces the sampling rate from DMCLK/8 to DMCLK/

256, and increases the resolution from a single bit to 15 bits or

greater (depending on chosen sampling rate). Its Z transform is

given as: [(1–Z^–N)/(1–Z^–1)]³where N is set by the sampling rate

(N = 32 @ 64 kHz sampling . . . N = 256 @ 8 kHz sampling)

Thus when the sampling rate is 64 kHz a minimal group delay

of 25 µs can be achieved.

DAC Coding

The DAC coding scheme is in twos complement format with

0x7FFF being full-scale positive and 0x8000 being full-scale

negative.

Interpolation Filter

Word growth in the decimator is determined by the sampling

rate. At 64 kHz sampling, where the oversampling ratio between

sigma-delta modulator and decimator output equals 32, we get

five bits per stage of the three stage Sinc3 filter. Due to symme-

try within the sigma-delta modulator, the LSB will always be a

zero, therefore the 16-bit ADC output word will have 2 LSBs

equal to zero, one due to the sigma-delta symmetry and the

other being a padding zero to make up the 16-bit word. At

lower sampling rates, decimator word growth will be greater

than the 16-bit sample word, therefore truncation occurs in

transferring the decimator output as the ADC word. For example

at 8 kHz sampling, word growth reaches 24 bits due to the OSR

of 256 between sigma-delta modulator and decimator output.

This yields eight bits per stage of the 3-stage Sinc3 filter.

The anti-imaging interpolation filter is a sinc-cubed digital filter

that up-samples the 16-bit input words from the input sample

rate to a rate of DMCLK/8, while filtering to attenuate images

produced by the interpolation process. Its’ Z transform is given

as: [(1–Z^–N)/(1–Z^–1)]³where N is determined by the sampling

rate (N = 32 @ 64 kHz . . . N = 256 @ 8 kHz). The DAC re-

ceives 16-bit samples from the host DSP processor at the pro-

grammed sample rate of DMCLK/N. If the host processor fails

to write a new value to the serial port, the existing (previous)

data is read again. The data stream is filtered by the anti-imaging

interpolation filter, but there is an option to bypass the interpo-

lator for the minimum group delay configuration by setting the

IBYP bit (CRE:5) of Control Register E. The interpolation filter

has the same characteristics as the ADC’s antialiasing decima-

tion filter.

ADC Coding

The ADC coding scheme is in twos complement format (see

Figure 6). The output words are formed by the decimation

filter, which grows the word length from the single-bit output of

the sigma-delta modulator to a word length of up to 18 bits

(depending on decimation rate chosen), which is the final out-

put of the ADC block. In Data Mode this value is truncated to

16 bits for output on the Serial Data Output (SDO) pin. For

input values equal to or greater than positive full scale, however,

The output of the interpolation filter is fed to the DAC’s digital

sigma-delta modulator, which converts the 16-bit data to 1-bit

samples at a rate of DMCLK/8. The modulator noise-shapes

the signal so that errors inherent to the process are minimized in

the passband of the converter. The bitstream output of the

sigma-delta modulator is fed to the single bit DAC where it is

converted to an analog voltage.

Analog Smoothing Filter and PGA

The output of the single-bit DAC is sampled at DMCLK/8,

therefore it is necessary to filter the output to reconstruct the

low frequency signal. The decoder’s analog smoothing filter

consists of a continuous-time filter preceded by a third-order

switched-capacitor filter. The continuous-time filter forms part

of the output programmable gain amplifier (PGA). The PGA

can be used to adjust the output signal level from –15 dB to

+6 dB in 3 dB steps, as shown in Table II. The PGA gain is

set by bits OGS0, OGS1 and OGS2 (CRD:4-6) in Control

Register D.

V

+ (V

؋

0.32875)

FBP

REF

ANALOG

INPUT

V

REF

V

FBN

V

– (V

؋

0.32875)

REF

10...00

00...00

01...11

ADC CODE DIFFERENTIAL

Table II. PGA Settings for the Decoder Channel

V

+ (V

؋

0.6575)

REF

OGS2

OGS1

OGS0

Gain (dB)

V

FBP

ANALOG

INPUT

0

1

0

1

0

1

0

1

0

1

0

1

0

1

+6

+3

0

–3

–6

–9

–12

–15

V

REF

V

– (V

؋

0.6575)

FBN

REF

10...00

00...00

01...11

ADC CODE SINGLE-ENDED

Figure 6. ADC Transfer Function

–12–

REV. 0

AD73422

Differential Output Amplifiers

Table III. Analog Gain Tap Settings*

The decoder has a differential analog output pair (VOUTP and

VOUTN). The output channel can be muted by setting the

MUTE bit (CRD:7) in Control Register D. The output signal is

dc-biased to the codec’s on-chip voltage reference.

AGTC4

AGTC3 AGTC2 AGTC1 AGTC0 Gain

0

—

0

1

—

1

0

+1.00

0

—

1

0

—

1

0

1

—

1

0

—

1

0

1

0

—

1

0

—

0

1

0

1

0

—

1

0

—

1

0

+0.9375

+0.875

+0.8125

+0.075

—

+0.0625

–0.0625

—

Voltage Reference

The AD73422 reference, REFCAP, is a bandgap reference that

provides a low noise, temperature-compensated reference to the

DAC and ADC. A buffered version of the reference is also made

available on the REFOUT pin and can be used to bias other

external analog circuitry. The reference has a nominal value of

1.2 V.

–0.875

–0.9375

–1.00

The reference output (REFOUT) can be enabled for biasing

external circuitry by setting the RU bit (CRC:6) of CRC.

1

*AGE and DGT weights are given for the case of VFBNx (connected to the

sigma-delta modulator’s positive input) being at a higher potential than VFBPx

(connected to the sigma-delta modulator’s negative input).

ANALOG

LOOP-BACK

SELECT

SINGLE-ENDED

ENABLE

INVERTING

OP AMPS

INVERT

VFBN1

VINN1

Digital Gain Tap

The digital gain tap features a programmable gain block whose

input is taken from the bitstream from the ADC’s sigma-delta

modulator. This single bit input (1 or 0) is used to add or sub-

tract a programmable value, which is the digital gain tap setting,

to the output of the DAC section’s interpolator. The program-

mable setting has 16-bit resolution and is programmed using the

settings in Control Registers G and H.

V

REF

0/38dB

PGA

VINP1

VFBP1

GAIN

1

V

REF

ANALOG

GAIN TAP

VOUTP1

VOUTN1

CONTINUOUS

TIME

LOW-PASS

FILTER

Table IV. Digital Gain Tap Settings*

+6/–15dB

PGA

DGT15-0 (Hex)

Gain

0x8000

0x9000

0xA000

0xC000

0xE000

0x0000

0x2000

0x4000

0x6000

0x7FFF

–1.00

–0.875

–0.75

–0.5

–0.25

–0.00

+0.25

+0.5

AD73422

REFOUT

REFCAP

REFERENCE

AFE SECTION

Figure 7. Analog Input/Output Section

Analog and Digital Gain Taps

The AD73422 features analog and digital feedback paths be-

tween input and output. The amount of feedback is determined

by the gain setting that is programmed in the control registers.

This feature can typically be used for balancing the effective

impedance between input and output when used in Subscriber

Line Interface Circuit (SLIC) interfacing.

+0.75

+0.99999

*AGE and DGT weights are given for the case of VFBNx (connected to the

sigma-delta modulator’s positive input) being at a higher potential than VFBPx

(connected to the sigma-delta modulator’s negative input).

Analog Gain Tap

AFE Serial Port (SPORT2)

The analog gain tap is configured as a programmable differential

amplifier whose input is taken from the ADC’s input signal

path. The output of the analog gain tap is summed with the

output of the DAC. The gain is programmable using Control

Register F (CRF:0-4) to achieve a gain of –1 to +1 in 32 steps,

with muting being achieved through a separate control setting

(Control Register F Bit _). The gain increment per step is 0.0625.

The AGT is enabled by powering up the AGT control bit in the

power control register (CRC:1). When this bit is set (=1) CRF

becomes an AGT control register with CRF:0-4 holding the

AGT coefficient, CRF:5 becomes an AGT enable and CRF:7

becomes an AGT mute control bit. Control bit CRF:5 connects/

disconnects the AGT output to the summer block at the output

of the DAC section while control bit CRF:7 overrides the gain

tap setting with a mute, or zero gain, setting (which is omitted

from the gain settings). Table III shows the gain versus digital

setting for the AGT.

The AFE section communicates with the DSP section via its

bidirectional synchronous serial port (SPORT2), which interfaces

to either SPORT0 or SPORT1 of the DSP section. SPORT2 is

used to transmit and receive digital data and control informa-

tion. The dual AFE is implemented using two separate AFE

blocks that are internally cascaded with serial port access to the

input of AFE Channel 1 and the output of AFE Channel 2.

This allows other single or dual codec devices to be cascaded

together (up to a limit of eight codec units).

In both transmit and receive modes, data is transferred at the

serial clock (SCLK2) rate with the MSB being transferred first.

Communications between the AFE section and the DSP section

must always be initiated by the AFE section (AFE is in master

mode—DSP SPORT is in slave mode). This ensures that there

is no collision between input data and output samples.

REV. 0

–13–

AD73422

AMCLK

(EXTERNAL)

AMCLK

(EXTERNAL)

DMCLK

(INTERNAL)

DMCLK

(INTERNAL)

AMCLK

DIVIDER

AMCLK

DIVIDER

3

SCLK

SE

SCLK

DIVIDER

SCLK

DIVIDER

RESET

SERIAL PORT 1

SERIAL PORT 2

(SPORT 1)

(SPORT 2)

(SDOFS1)

(SDO1)

SDOFS

SDO

SDIFS

SDI

(SDIFS2)

(SDI2)

SERIAL REGISTER 1

SERIAL REGISTER

2

8

CONTROL

REGISTER

1E

CONTROL

REGISTER

2E

CONTROL

REGISTER

1C

CONTROL

REGISTER

2C

CONTROL

REGISTER

1A

CONTROL

REGISTER

1B

CONTROL

REGISTER

1D

CONTROL

REGISTER

2A

CONTROL

REGISTER

2B

CONTROL

REGISTER

2D

8

16

CONTROL

REGISTER

1G

CONTROL

REGISTER

1F

CONTROL

REGISTER

2G

CONTROL

REGISTER

2F

CONTROL

REGISTER

1H

CONTROL

REGISTER

2H

Figure 8. SPORT2 Block Diagram

SPORT2 Overview

interfacing. The serial clock rate (CRB:2–3) defines how many

16-bit words can be written to a device before the next output

sample event will happen.

SPORT2 is a flexible, full-duplex, synchronous serial port

whose protocol has been designed to allow extra AFE devices

(AD733xx series), up to a maximum of eight I/O channels, to be

connected in cascade to a DSP SPORT (0 or 1). It has a very

flexible architecture that can be configured by programming two

of the internal control registers in each AFE block. SPORT2 has

three distinct modes of operation: Control Mode, Data Mode

and Mixed Control/Data Mode.

The SPORT2 block diagram, shown in Figure 8, details the

blocks associated with codecs 1 and 2, including the eight con-

trol registers (A–H), external AMCLK to internal DMCLK

divider and serial clock divider. The divider rates are controlled

by the setting of Control Register B. The AD73422 features a

master clock divider that allows users the flexibility of dividing

externally available high frequency DSP or CPU clocks to gen-

erate a lower frequency master clock internally in the codec

which may be more suitable for either serial transfer or sampling

rate requirements. The master clock divider has five divider

options (÷1 default condition, ÷2, ÷3, ÷4, ÷5) that are set by

loading the master clock divider field in Register B with the appro-

priate code. Once the internal device master clock (DMCLK) has

been set using the master clock divider, the sample rate and

serial clock settings are derived from DMCLK.

NOTE: As each AFE has its own control section, the register

settings in each must be programmed. The registers that control

serial transfer and sample rate operation (CRA and CRB) must

be programmed with the same values, otherwise incorrect opera-

tion may occur.

In Control Mode (CRA:0 = 0), the device’s internal configura-

tion can be programmed by writing to the eight internal control

registers. In this mode, control information can be written to or

read from the codec. In Data Mode (CRA:0 = 1), information

that is sent to the device is used to update the decoder section

(DAC), while the encoder section (ADC) data is read from the

device. In this mode, only DAC and ADC data is written to or

read from the device. Mixed mode (CRA:0 = 1 and CRA:1 = 1)

allows the user to choose whether the information being sent to

the device contains either control information or DAC data.

This is achieved by using the MSB of the 16-bit frame as a flag

bit. Mixed mode reduces the resolution to 15 bits with the MSB

being used to indicate whether the information in the 16-bit

frame is control information or DAC/ADC data.

The SPORT can work at four different serial clock (SCLK)

rates: chosen from DMCLK, DMCLK/2, DMCLK/4 or

DMCLK/8, where DMCLK is the internal or device master

clock resulting from the external or pin master clock being di-

vided by the master clock divider. When working at the lower

SCLK rate of DMCLK/8, which is intended for interfacing with

slower DSPs, the SPORT will support a maximum of two codecs

in cascade (a single AD73422 or two AD73311s) with the sample

rate of DMCLK/256.

SPORT2 Register Maps

SPORT2 features a single 16-bit serial register that is used for

both input and output data transfers. As the input and output

data must share the same register, some precautions must be

observed. The primary precaution is that no information must

be written to SPORT2 without reference to an output sample

event, which is when the serial register will be overwritten with

the latest ADC sample word. Once SPORT2 starts to output

the latest ADC word, it is safe for the DSP to write new control

or data words to the codec. In certain configurations, data can

be written to the device to coincide with the output sample

being shifted out of the serial register—see section on AFE

There are two register banks for each AFE channel in the

AD73422: the control register bank and the data register bank.

The control register bank consists of eight read/write registers,

each eight bits wide. Table IX shows the control register map

for the AD73422. The first two control registers, CRA and

CRB, are reserved for controlling serial activity. They hold

settings for parameters such as serial clock rate, internal master

clock rate, sample rate and device count. As both codecs are

internally cascaded, registers CRA and CRB on each codec

must be programmed with the same setting to ensure correct

operation (this is shown in the programming examples). The

–14–

REV. 0

AD73422

other five registers; CRC through CRH are used to hold control

settings for the ADC, DAC, Reference, Power Control and

Gain Tap sections of the device. It is not necessary that the

contents of CRC through CRH on each codec are similar. Con-

trol registers are written to on the negative edge of SCLK. The

data register bank consists of two 16-bit registers that are the

DAC and ADC registers.

Sample Rate Divider

The AD73422 features a programmable sample rate divider that

allows users flexibility in matching the codec’s ADC and DAC

sample rates (decimation/interpolation rates) to the needs of the

DSP software. The maximum sample rate available is DMCLK/

256, which offers the lowest conversion group delay, while the

other available rates are: DMCLK/512, DMCLK/1024 and

DMCLK/2048. The slowest rate (DMCLK/2048) is the default

sample rate. The sample rate divider is programmable by setting

bits CRB:0-1. Table VII shows the sample rate corresponding to

the various bit settings.

Master Clock Divider

The AD73422’s AFE features a programmable master clock

divider that allows the user to reduce an externally available

master clock, at pin AMCLK, by one of the ratios 1, 2, 3, 4 or

5, to produce an internal master clock signal (DMCLK) that is

used to calculate the sampling and serial clock rates. The master

clock divider is programmable by setting CRB:4-6. Table V

shows the division ratio corresponding to the various bit set-

tings. The default divider ratio is divide-by-one.

Table VII. Sample Rate Divider Settings

DIR1

DIR0

SCLK Rate

0

1

0

1

0

1

DMCLK/2048

DMCLK/1024

DMCLK/512

DMCLK/256

Table V. DMCLK (Internal) Rate Divider Settings

MCD2

MCD1

MCD0

DMCLK Rate

DAC Advance Register

0

1

0

1

0

1

0

1

0

1

0

1

0

1

AMCLK

The loading of the DAC is internally synchronized with the

unloading of the ADC data in each sampling interval. The de-

fault DAC load event happens one SCLK cycle before the

SDOFS flag is raised by the ADC data being ready. However,

this DAC load position can be advanced before this time by

modifying the contents of the DAC Advance field in Control

Register E (CRE:0–4). The field is five bits wide, allowing 31

increments of weight 1/(F_S× 32); see Table VIII. The sample

rate F_Sis dependent on the setting of both the AMCLK divider

and the Sample Rate divider; see Tables VII and IX. In certain

circumstances this DAC update adjustment can reduce the

group delay when the ADC and DAC are used to process data

in series. See AD73322 data sheet (Appendix C) for details of

how the DAC advance feature can be used.

AMCLK/2

AMCLK/3

AMCLK/4

AMCLK/5

AMCLK

Serial Clock Rate Divider

The AD73422’s AFE features a programmable serial clock

divider that allows users to match the serial clock (SCLK) rate

of the data to that of the DSP engine or host processor. The

maximum SCLK rate available is DMCLK, and the other avail-

able rates are: DMCLK/2, DMCLK/4 and DMCLK/8. The

slowest rate (DMCLK/8) is the default SCLK rate. The serial

clock divider is programmable by setting bits CRB:2–3. Table

VI shows the serial clock rate corresponding to the various bit

settings.

NOTE: The DAC advance register should not be changed while

the DAC section is powered up.

Table VIII. DAC Timing Control

DA4

DA3

DA2

DA1

DA0

Time Advance

Table VI. SCLK Rate Divider Settings

0

—

1

0

—

1

0

—

1

0

1

—

1

0

1

0

—

0

0 s

SCD1

SCD0

SCLK Rate

1/(F_S× 32) s

2/(F_S× 32) s

—

30/(F_S× 32) s

31/(F_S× 32) s

0

1

0

1

0

1

DMCLK/8

DMCLK/4

DMCLK/2

DMCLK

1

Table IX. Control Register Map

Address (Binary)

Name

Description

Type

Width

Reset Setting (Hex)

000

001

010

011

100

CRA

CRB

CRC

CRD

CRE

CRF

CRG

CRH

Control Register A

Control Register B

Control Register C

Control Register D

Control Register E

Control Register F

Control Register G

Control Register H

R/W

8

0x00

REV. 0

–15–

AD73422

Table X. Control Word Description

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

0

C/D

R/W

DEVICE ADDRESS

REGISTER ADDRESS

REGISTER DATA

Control

Frame

Description

Bit 15

Control/Data

When set high, it signifies a control word in Program or Mixed Program/Data Modes. When set low, it

signifies a data word in Mixed Program/Data Mode or an invalid control word in Program Mode.

Bit 14

Read/Write

When set low, it tells the device that the data field is to be written to the register selected by the regis-

ter field setting provided the address field is zero. When set high, it tells the device that the selected

register is to be written to the data field in the input serial register and that the new control word is to

be output from the device via the serial output.

Bits 13–11 Device Address This 3-bit field holds the address information. Only when this field is zero is a device selected. If the

address is not zero, it is decremented and the control word is passed out of the device via the serial

output.

Bits 10–8 Register Address This 3-bit field is used to select one of the five control registers on the AFE section of the AD73422.

Bits 7–0

Register Data

This 8-bit field holds the data that is to be written to or read from the selected register provided the

address field is zero.

Table XI. Control Register A Description

CONTROL REGISTER A

7

6

5

4

3

2

1

0

DATA/

PGM

RESET

DC2

DC1

DC0

SLB

DLB

MM

Bit

Name

Description

0

1

2

3

4

5

6

7

DATA/PGM Operating Mode (0 = Program; 1 = Data Mode)

MM

DLB

SLB

DC0

DC1

DC2

RESET

Mixed Mode (0 = Off; 1 = Enabled)

Digital Loop-Back Mode (0 = Off; 1 = Enabled)

SPORT Loop-Back Mode (0 = Off; 1 = Enabled)

Device Count (Bit 0)

Device Count (Bit 1)

Device Count (Bit 2)

Software Reset (0 = Off; 1 = Initiates Reset)

Table XII. Control Register B Description

CONTROL REGISTER B

7

6

5

4

3

2

1

0

CEE

MCD2 MCD1 MCD0

SCD1

SCD0

DIR1

DIR0

Bit

Name

Description

0

1

2

3

4

5

6

7

DIR0

DIR1

Decimation/Interpolation Rate (Bit 0)

Decimation/Interpolation Rate (Bit 1)

Serial Clock Divider (Bit 0)

SCD0

SCD1

MCD0

MCD1

MCD2

CEE

Serial Clock Divider (Bit 1)

Master Clock Divider (Bit 0)

Master Clock Divider (Bit 1)

Master Clock Divider (Bit 2)

Control Echo Enable (0 = Off; 1 = Enabled)

–16–

REV. 0

AD73422

Table XIII. Control Register C Description

CONTROL REGISTER C

CONTROL REGISTER D

CONTROL REGISTER E

7

6

5

4

3

2

1

0

5VEN

RU

PUREF PUDAC PUADC PUIA PUAGT

PU

Bit

Name

Description

0

1

2

3

4

5

6

7

PU

Power-Up Device (0 = Power-Down; 1 = Power-On)

PUAGT

PUIA

PUADC

PUDAC

PUREF

RU

Analog Gain Tap Power (0 = Power-Down; 1 = Power-On)

Input Amplifier Power (0 = Power-Down; 1 = Power-On)

ADC Power (0 = Power-Down; 1 = Power-On)

DAC Power (0 = Power-Down; 1 = Power-On)

REF Power (0 = Power-Down; 1 = Power On)

REFOUT Use (0 = Disable REFOUT; 1 = Enable REFOUT)

Reserved (Must be Programmed to 0)

—

Table XIV. Control Register D Description

7

6

5

4

3

2

1

0

MUTE OGS2

OGS1

OGS0 RMOD

IGS2

IGS1

IGS0

Bit

Name

Description

0

1

2

3

4

5

6

7

IGS0

IGS1

IGS2

RMOD

OGS0

OGS1

OGS2

MUTE

Input Gain Select (Bit 0)

Input Gain Select (Bit 1)

Input Gain Select (Bit 2)

Reset ADC Modulator (0 = Off; 1 = Reset Enabled)

Output Gain Select (Bit 0)

Output Gain Select (Bit 1)

Output Gain Select (Bit 2)

Output Mute (0 = Mute Off; 1 = Mute Enabled)

Table XV. Control Register E Description

7

6

5

4

3

2

1

0

TME

DGTE

IBYP

DA4

DA3

DA2

DA1

DA0

Bit

Name

Description

0

1

2

3

4

5

DA0

DA1

DA2

DA3

DA4

IBYP

DAC Advance Setting (Bit 0)

DAC Advance Setting (Bit 1)

DAC Advance Setting (Bit 2)

DAC Advance Setting (Bit 3)

DAC Advance Setting (Bit 4)

Interpolator Bypass (0 = Bypass Disabled;

1 = Bypass Enabled)

6

7

DGTE

TME

Digital Gain Tap Enable (0 = Disabled; 1 = Enabled)

Test Mode Enable (0 = Disabled; 1 = Enabled)

REV. 0

–17–

AD73422

Table XVI. Control Register F Description

CONTROL REGISTER F

7

6

5

4

3

2

1

0

ALB/

AGTM

SEEN/

AGTE

INV

AGTC4 AGTC3 AGTC2 AGTC1 AGTC0

Bit

Name

Description

0

1

2

3

4

5

AGTC0

AGTC1

AGTC2

AGTC3

AGTC4

SEEN/

AGTE

INV

Analog Gain Tap Coefficient (Bit 0)

Analog Gain Tap Coefficient (Bit 1)

Analog Gain Tap Coefficient (Bit 2)

Analog Gain Tap Coefficient (Bit 3)

Analog Gain Tap Coefficient (Bit 4)

Single-Ended Enable (0 = Disabled; 1 = Enabled)

Analog Gain Tap Enable (0 = Disabled; 1 = Enabled)

Input Invert (0 = Disabled; 1 = Enabled)

Analog Loop-Back of Output to Input (0 = Disabled; 1 = Enabled)

Analog Gain Tap Mute (0 = Off; 1 = Muted)

6

7

ALB/

AGTM

Table XVII. Control Register G Description

CONTROL REGISTER G

7

6

5

4

3

2

1

0

DGTC7 DGTC6 DGTC5 DGTC4 DGTC3 DGTC2 DGTC1 DGTC0

Bit

Name

Description

0

1

2

3

4

5

6

7

DGTC0

DGTC1

DGTC2

DGTC3

DGTC4

DGTC5

DGTC6

DGTC7

Digital Gain Tap Coefficient (Bit 0)

Digital Gain Tap Coefficient (Bit 1)

Digital Gain Tap Coefficient (Bit 2)

Digital Gain Tap Coefficient (Bit 3)

Digital Gain Tap Coefficient (Bit 4)

Digital Gain Tap Coefficient (Bit 5)

Digital Gain Tap Coefficient (Bit 6)

Digital Gain Tap Coefficient (Bit 7)

Table XVIII. Control Register H Description

CONTROL REGISTER H

7

6

5

4

3

2

1

0

DGTC15 DGTC14 DGTC13 DGTC12 DGTC11 DGTC10 DGTC9 DGTC8

Bit

Name

Description

0

1

2

3

4

5

6

7

DGTC8

DGTC9

Digital Gain Tap Coefficient (Bit 8)

Digital Gain Tap Coefficient (Bit 9)

Digital Gain Tap Coefficient (Bit 10)

Digital Gain Tap Coefficient (Bit 11)

Digital Gain Tap Coefficient (Bit 12)

Digital Gain Tap Coefficient (Bit 13)

Digital Gain Tap Coefficient (Bit 14)

Digital Gain Tap Coefficient (Bit 15)

DGTC10

DGTC11

DGTC12

DGTC13

DGTC14

DGTC15

–18–

REV. 0

AD73422

OPERATION

Resetting the AD73422’s AFE

word is passed out of the device—either to the next device in a

cascade or back to the DSP engine. This 3-bit address format

allows the user to uniquely address any one of up to eight de-

vices in a cascade; please note that this addressing scheme is

valid only in sending control information to the device—a differ-

ent format is used to send DAC data to the device(s). As the

AD73422 features a dual AFE, these two channels have sepa-

rate device addresses for programming purposes—the two de-

vice addresses correspond to 0 and 1.

The pin ARESET resets all the control registers. All registers are

reset to zero indicating that the default SCLK rate (DMCLK/8)

and sample rate (DMCLK/2048) are at a minimum to ensure

that slow speed DSP engines can communicate effectively. As

well as resetting the control registers using the ARESET pin, the

device can be reset using the RESET bit (CRA:7) in Control

Register A. Both hardware and software resets require four

DMCLK cycles. On reset, DATA/PGM (CRA:0) is set to 0

(default condition) thus enabling Program Mode. The reset

conditions ensure that the device must be programmed to the

correct settings after power-up or reset. Following a reset, the

SDOFS will be asserted 2048 DMCLK cycles after ARESET

going high. The data that is output following reset and during

Program Mode is random and contains no valid information

until either data or mixed mode is set.

Following reset, when the SE pin is enabled, the codec responds

by raising the SDOFS pin to indicate that an output sample

event has occurred. Control words can be written to the device

to coincide with the data being sent out of the SPORT or they

can lag the output words by a time interval that should not

exceed the sample interval. After reset, output frame sync pulses

will occur at a slower default sample rate, which is DMCLK/

2048, until Control Register B is programmed after which the

SDOFS pulses will revert to the DMCLK/256 rate. During

Program Mode, the data output by the ADCs is random and

should not be interpreted as valid data.

Power Management

The individual functional blocks of the AD73422 can be en-

abled separately by programming the power control register

CRC. It allows certain sections to be powered down if not re-

quired, which adds to the device’s flexibility in that the user

need not incur the penalty of having to provide power for a

certain section if it is not necessary to their design. The power

control registers provides individual control settings for the

major functional blocks on each codec unit and also a global

override that allows all sections to be powered up by setting the

bit. Using this method the user could, for example, individually

enable a certain section, such as the reference (CRC:5), and

disable all others. The global power-up (CRC:0) can be used to

enable all sections but if power-down is required using the glo-

bal control, the reference will still be enabled, in this case, be-

cause its individual bit is set. Refer to Table XIII for details of

the settings of CRC.

Data Mode

Once the device has been configured by programming the cor-

rect settings to the various control registers, the device may exit

Program Mode and enter Data Mode. This is done by program-

ming the DATA/PGM (CRA:0) bit to a 1 and MM (CRA:1) to

0. Once the device is in Data Mode, the 16-bit input data frame

is now interpreted as DAC data rather than a control frame.

This data is therefore loaded directly to the DAC register. In

Data Mode, as the entire input data frame contains DAC data,

the device relies on counting the number of input frame syncs

received at the SDIFS pin. When that number equals the device

count stored in the device count field of CRA, the device knows

that the present data frame being received is its own DAC up-

date data. When the device is in normal Data Mode (i.e., mixed

mode disabled), it must receive a hardware reset to reprogram

any of the control register settings. In a single AD73422 con-

figuration, each 16-bit data frame sent from the DSP to the

device is interpreted as DAC data but it is necessary to send two

DAC words per sample period in order to ensure DAC update.

Also as the device count setting defaults to 1, it must be set

to 2 (001b) to ensure correct update of both DACs on the

AD73422.

NOTE: As both codec units share a common reference, the

reference control bits (CRC:5–7) in each SPORT are wire ORed

to allow either device to control the reference. Hence the refer-

ence is only in a reset state when the relevant control bit of both

codec units is set to 0.

AFE Operating Modes

There are three main modes of operation available on the

AD73422; Program, Data and Mixed Program/Data modes.

There are also two other operating modes which are typically

reserved as diagnostic modes: Digital and SPORT Loopback.

The device configuration—register settings—can be changed

only in Program and Mixed Program/Data Modes. In all modes,

transfers of information to or from the device occur in 16-bit

packets, therefore the DSP engine’s SPORT will be programmed

for 16-bit transfers.

Mixed Program/Data Mode

This mode allows the user to send control words to the device

along with the DAC data. This permits adaptive control of the

device whereby control of the input/output gains can be effected

by interleaving control words along with the normal flow of

DAC data. The standard data frame remains 16 bits, but now

the MSB is used as a flag bit to indicate whether the remaining

15 bits of the frame represent DAC data or control information.

In the case of DAC data, the 15 bits are loaded with MSB

justification and LSB set to 0 to the DAC register. Mixed mode

is enabled by setting the MM bit (CRA:1) to 1 and the DATA/

PGM bit (CRA:0) to 1. In the case where control setting changes

will be required during normal operation, this mode allows the

ability to load both control and data information with the slight

inconvenience of formatting the data. Note that the output

samples from the ADC will also have the MSB set to zero to

indicate it is a data word.

Program (Control) Mode

In Program Mode, CRA:0 = 0, the user writes to the control

registers to set up the device for desired operation—SPORT

operation, cascade length, power management, input/output

gain, etc. In this mode, the 16-bit information packet sent to the

device by the DSP engine is interpreted as a control word whose

format is shown in Table X. In this mode, the user must address

the device to be programmed using the address field of the con-

trol word. This field is read by the device and if it is zero (000 bin)

then the device recognizes the word as being addressed to it. If the

address field is not zero, it is then decremented and the control

REV. 0

–19–

AD73422

A description of a single device operating in mixed mode is

detailed in Appendix B, while Appendix D details the initializa-

tion and operation of a dual codec cascade operating in mixed

mode. Note that it is not essential to load the control registers in

Program Mode before setting mixed mode active. It is also

possible to initiate mixed mode by programming CRA with the

first control word and then interleaving control words with

DAC data.

which is active high one clock cycle before the start of the 16-bit

word or during the last bit of the previous word if transmission

is continuous. The serial clock (SCLK) is an output from the

codec and is used to define the serial transfer rate to the DSP’s

Tx and Rx ports. Two primary configurations can be used: the

first is shown in Figure 10 where the DSP’s Tx data, Tx frame

sync, Rx data and Rx frame sync are connected to the codec’s

SDI, SDIFS, SDO and SDOFS respectively. This configura-

tion, referred to as indirectly coupled or nonframe sync loop-

back, has the effect of decoupling the transmission of input data

from the receipt of output data. The delay between receipt of

codec output data and transmission of input data for the codec

is determined by the DSP’s software latency. When program-

ming the DSP serial port for this configuration, it is necessary to

set the Rx FS as an input and the Tx FS as an output generated

by the DSP. This configuration is most useful when operating in

mixed mode, as the DSP has the ability to decide how many

words (either DAC or control) can be sent to the codecs. This

means that full control can be implemented over the device

configuration as well as updating the DAC in a given sample

interval. The second configuration (shown in Figure 11) has the

DSP’s Tx data and Rx data connected to the codec’s SDI and

SDO, respectively while the DSP’s Tx and Rx frame syncs are

connected to the codec’s SDIFS and SDOFS. In this configura-

tion, referred to as directly coupled or frame sync loop-back, the

frame sync signals are connected together and the input data to

the codec is forced to be synchronous with the output data from

the codec. The DSP must be programmed so that both the Tx

FS and Rx FS are inputs as the codec SDOFS will be input to

both. This configuration guarantees that input and output

events occur simultaneously and is the simplest configuration

for operation in normal Data Mode. Note that when program-

ming the DSP in this configuration it is advisable to preload the

Tx register with the first control word to be sent before the

codec is taken out of reset. This ensures that this word will be

transmitted to coincide with the first output word from the

device(s).

Digital Loop-Back

This mode can be used for diagnostic purposes and allows the

user to feed the ADC samples from the ADC register directly to

the DAC register. This forms a loop-back of the analog input to

the analog output by reconstructing the encoded signal using

the decoder channel. The serial interface will continue to work,

which allows the user to control gain settings, etc. Only when

DLB is enabled with mixed mode operation can the user disable

the DLB, otherwise the device must be reset.

SPORT Loop-Back

This mode allows the user to verify the DSP interfacing and

connection by writing words to the SPORT of the devices and

have them returned back unchanged after a delay of 16 SCLK

cycles. The frame sync and data words that are sent to the de-

vice are returned via the output port. Again, SLB mode can only

be disabled when used in conjunction with mixed mode, other-

wise the device must be reset.

Analog Loop-Back

In Analog Loop-Back mode, the differential DAC output is

connected, via a loop-back switch, to the ADC input. This

mode allows the ADC channel to check functionality of the

DAC channel as the reconstructed output signal can be moni-

tored using the ADC as a sampler. Analog Loop-Back is en-

abled by setting the ALB bit (CRF:7)

NOTE: Analog Loop-Back can only be enabled if the Analog

Gain Tap is powered down (CRC:1 = 0).

ANALOG

LOOP-BACK

SELECT

SINGLE-ENDED

ENABLE

INVERTING

OP AMPS

INVERT

TFS (0/1)

DT (0/1)

SDIFS

SDI

VFBN1

VINN1

CHANNEL 1

CHANNEL 2

DSP

SECTION

AFE

SECTION

SCLK (0/1)

DR (0/1)

SCLK2

SDO

V

REF

0/38dB

PGA

VINP1

RFS (0/1)

SDOFS

VFBP1

GAIN

1

AD73422

V

REF

ANALOG GAIN TAP

POWERED DOWN

Figure 10. Indirectly Coupled or Nonframe Sync Loop-

Back Configuration

VOUTP1

VOUTN1

CONTINUOUS

TIME

Cascade Operation

+6/–15dB

LOW-PASS

FILTER

PGA

The AD73422 has been designed to support cascading of extra

external AFEs from either SPORT0 or SPORT1. Cascaded

operation can support mixes of dual or single channel devices with

maximum number of codec units being eight (the AD73422 has

two codec units configured on the device). The SPORT2 inter-

face protocol has been designed so that device addressing is

built into the packet of information sent to the device. This

allows the cascade to be formed with no extra hardware over-

head for control signals or addressing. A cascade can be formed

in either of the two modes previously discussed.

AD73422

AFE SECTION

REFOUT

REFCAP

REFERENCE

Figure 9. Analog Loop-Back Connectivity

AFE Interfacing

The AFE section SPORT (SPORT2) can be interfaced to either

SPORT0 or SPORT1 of the DSP section. Both serial input and

output data use an accompanying frame synchronization signal

–20–

REV. 0

AD73422

There may be some restrictions in cascade operation due to the

number of devices configured in the cascade and the sampling

rate and serial clock rate chosen. The following relationship

details the restrictions in configuring a codec cascade.

FUNCTIONAL DESCRIPTION—DSP

The AD73422 instruction set provides flexible data moves and

multifunction (one or two data moves with a computation)

instructions. Every instruction can be executed in a single pro-

cessor cycle. The AD73422 assembly language uses an algebraic

syntax for ease of coding and readability. A comprehensive set

of development tools supports program development.

Number of Codecs × Word Size (16) × Sampling Rate ≤ Serial

Clock Rate

POWER-DOWN

TFS (0/1)

DT (0/1)

SDIFS

SDI

FULL MEMORY

MODE

CONTROL

CHANNEL 1

CHANNEL 2

DATA

MEMORY

PROGRAMMABLE

ADDRESS

EXTERNAL

ADDRESS

BUS

16K PM

(OPTIONAL (OPTIONAL

8K) 8K)

16K DM

PROGRAM

I/O

GENERATORS

AFE

SECTION

SEQUENCER

DSP

SECTION

AND

FLAGS

SCLK (0/1)

DR (0/1)

SCLK2

SDO

DAG 1 DAG 2

EXTERNAL

DATA

BUS

PROGRAM MEMORY ADDRESS

DATA MEMORY ADDRESS

RFS (0/1)

SDOFS

BYTE DMA

CONTROLLER

AD73422

PROGRAM MEMORY DATA

DATA MEMORY DATA

OR

Figure 11. Directly Coupled or Frame Sync Loop-

Back Configuration

EXTERNAL

DATA

BUS

ARITHMETIC UNITS

ALU MAC SHIFTER

SERIAL PORTS

TIMER

INTERNAL

DMA

PORT

SPORT 0 SPORT 1

When using the indirectly coupled frame sync configuration in

cascaded operation, it is necessary to be aware of the restrictions

in sending data to all devices in the cascade. Effectively the time

allowed is given by the sampling interval (M/DMCLK, where M

can be one of 256, 512, 1024 or 2048) which is 125 µs for a

sample rate of 8 kHz. In this interval, the DSP must transfer

N × 16 bits of information, where N is the number of devices in

the cascade. Each bit will take 1/SCLK and, allowing for any

latency between the receipt of the Rx interrupt and the trans-

mission of the Tx data, the relationship for successful operation

is given by:

ADSP-2100 BASE

ARCHITECTURE

HOST MODE

SERIAL PORT

SPORT 2

REF

ADC1

DAC1

ADC2

DAC2

ANALOG FRONT END

SECTION

Figure 12. Functional Block Diagram

Figure 12 is an overall block diagram of the AD73422. The

processor contains three independent computational units: the

ALU, the multiplier/accumulator (MAC) and the shifter. The

computational units process 16-bit data directly and have provi-

sions to support multiprecision computations. The ALU per-

forms a standard set of arithmetic and logic operations; division

primitives are also supported. The MAC performs single-cycle

multiply, multiply/add and multiply/subtract operations with

40 bits of accumulation. The shifter performs logical and arith-

metic shifts, normalization, denormalization and derive expo-

nent operations.

M/DMCLK > ((N × 16/SCLK) + T_{INTERRUPT LATENCY}

)

The interrupt latency will include the time between the ADC

sampling event and the RX interrupt being generated in the

DSP—this should be 16 SCLK cycles.

As the AD73422 is configured in Cascade Mode, each device

must know the number of devices in the cascade because the

Data and Mixed modes use a method of counting input frame

sync pulses to decide when they should update the DAC

register from the serial input register. Control Register A con-

tains a 3-bit field (DC0–2) that is programmed by the DSP

during the programming phase. The default condition is that the

field contains 000b, which is equivalent to a single device in

cascade (see Table XIX). However, for cascade operation this

field must contain a binary value that is one less than the number

of devices in the cascade, which is 001b for a single AD73422

device configuration.

The shifter can be used to efficiently implement numeric

format control including multiword and block floating-point

representations.

The internal result (R) bus connects the computational units so

that the output of any unit may be the input of any unit on the

next cycle.

A powerful program sequencer and two dedicated data address

generators ensure efficient delivery of operands to these compu-

tational units. The sequencer supports conditional jumps, sub-

routine calls and returns in a single cycle. With internal loop

counters and loop stacks, the AD73422 executes looped code

with zero overhead; no explicit jump instructions are required to

maintain loops.

Table XIX. Device Count Settings

DC2

DC1

DC0

Cascade Length

0

1

0

1

0

1

0

1

0

1

0

1

0

1

2

3

4

5

6

7

8

Two data address generators (DAGs) provide addresses for

simultaneous dual operand fetches (from data memory and

program memory). Each DAG maintains and updates four

address pointers. Whenever the pointer is used to access data

(indirect addressing), it is post-modified by the value of one of

four possible modify registers. A length value may be associated

with each pointer to implement automatic modulo addressing

for circular buffers.

REV. 0

–21–

AD73422

Serial Ports

Efficient data transfer is achieved with the use of five internal

buses:

The AD73422 incorporates two complete synchronous serial

ports (SPORT0 and SPORT1) for serial communications and

multiprocessor communication.

• Program Memory Address (PMA) Bus

• Program Memory Data (PMD) Bus

• Data Memory Address (DMA) Bus

• Data Memory Data (DMD) Bus

• Result (R) Bus

Here is a brief list of the capabilities of the AD73422 SPORTs.

For additional information on Serial Ports, refer to the ADSP-

2100 Family User’s Manual, Third Edition.

•

SPORTs are bidirectional and have a separate, double-

buffered transmit and receive section.

The two address buses (PMA and DMA) share a single external

address bus, allowing memory to be expanded off-chip, and the

two data buses (PMD and DMD) share a single external data

bus. Byte memory space and I/O memory space also share the

external buses.

SPORTs can use an external serial clock or generate their

own serial clock internally.

SPORTs have independent framing for the receive and trans-

mit sections. Sections run in a frameless mode or with frame

synchronization signals internally or externally generated.

Frame sync signals are active high or inverted, with either of

two pulsewidths and timings.

Program memory can store both instructions and data, permitting

the AD73422 to fetch two operands in a single cycle, one from

program memory and one from data memory. The AD73422

can fetch an operand from program memory and the next in-

struction in the same cycle.

•

SPORTs support serial data word lengths from 3 to 16 bits

and provide optional A-law and µ-law companding according

to CCITT recommendation G.711.

In lieu of the address and data bus for external memory connec-

tion, the AD73422 may be configured for 16-bit Internal DMA

port (IDMA port) connection to external systems. The IDMA

port is made up of 16 data/address pins and five control pins.

The IDMA port provides transparent, direct access to the DSPs

on-chip program and data RAM.

•

SPORT receive and transmit sections can generate unique

interrupts on completing a data word transfer.

SPORTs can receive and transmit an entire circular buffer of

data with only one overhead cycle per data word. An inter-

rupt is generated after a data buffer transfer.

An interface to low cost byte-wide memory is provided by the

Byte DMA port (BDMA port). The BDMA port is bidirectional

and can directly address up to four megabytes of external RAM

or ROM for off-chip storage of program overlays or data tables.

•

SPORT0 has a multichannel interface to selectively receive

and transmit a 24- or 32-word, time-division multiplexed,

serial bitstream.

The byte memory and I/O memory space interface supports

slow memories and I/O memory-mapped peripherals with pro-

grammable wait state generation. External devices can gain

control of external buses with bus request/grant signals (BR,

BGH, and BG). One execution mode (Go Mode) allows the

AD73422 to continue running from on-chip memory. Normal

execution mode requires the processor to halt while buses are

granted.

SPORT1 can be configured to have two external interrupts

(IRQ0 and IRQ1) and the Flag In and Flag Out signals. The

internally generated serial clock may still be used in this

configuration.

DSP SECTION PIN DESCRIPTIONS

The AD73422 will be available in a 119-ball PBGA package. In

order to maintain maximum functionality and reduce package

size and pin count, some serial port, programmable flag, inter-

rupt and external bus pins have dual, multiplexed functionality.

The external bus pins are configured during RESET only, while

serial port pins are software configurable during program

execution. Flag and interrupt functionality is retained concur-

rently on multiplexed pins. In cases where pin functionality is

reconfigurable, the default state is shown in plain text; alternate

functionality is shown in italics. See Pin Descriptions section.

The AD73422 can respond to eleven interrupts. There can be

up to six external interrupts (one edge-sensitive, two level-

sensitive and three configurable) and seven internal interrupts

generated by the timer, the serial ports (SPORTs), the Byte

DMA port and the power-down circuitry. There is also a master

RESET signal. The two serial ports provide a complete synchro-

nous serial interface with optional companding in hardware and

a wide variety of framed or frameless data transmit and receive

modes of operation.

Memory Interface Pins

Each port can generate an internal programmable serial clock or

accept an external serial clock.

The AD73422 processor can be used in one of two modes, Full

Memory Mode, which allows BDMA operation with full exter-

nal overlay memory and I/O capability, or Host Mode, which

allows IDMA operation with limited external addressing capa-

bilities. The operating mode is determined by the state of the

Mode C pin during RESET and cannot be changed while the

processor is running. See Full Memory Mode Pins and Host

Mode Pins tables for descriptions.

The AD73422 provides up to 13 general-purpose flag pins. The

data input and output pins on SPORT1 can be alternatively

configured as an input flag and an output flag. In addition, there

are eight flags that are programmable as inputs or outputs and

three flags that are always outputs.

A programmable interval timer generates periodic interrupts. A

16-bit count register (TCOUNT) is decremented every n pro-

cessor cycle, where n is a scaling value stored in an 8-bit register

(TSCALE). When the value of the count register reaches zero,

an interrupt is generated and the count register is reloaded from

a 16-bit period register (TPERIOD).

–22–

REV. 0

AD73422

Full Memory Mode Pins (Mode C = 0)

Pin # of Input/

Name(s) Pins Output Function

Pin Terminations (Continued)

I/O

Hi-Z*

Name

3-State Reset

Caused

By

Unused

Configuration

(Z)

State

A13:0

14

O

Address Output Pins for Program,

Data, Byte and I/O Spaces

CMS

RD

WR

BR

O (Z)

I

O

I

BR, EBR

Float

High (Inactive)

Float

D23:0

24

I/O

Data I/O Pins for Program, Data,

Byte and I/O Spaces (8 MSBs are

also used as Byte Memory

addresses)

BG

BGH

O (Z)

O

I

EE

Float

IRQ2/PF7 I/O (Z)

IRQL1/PF6 I/O (Z)

IRQL0/PF5 I/O (Z)

IRQE/PF4 I/O (Z)

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High or Low,

Output = Float

High or Low

Float

Input = High or Low,

Output = Float

High or Low

Host Mode Pins (Mode C = 1)

Pin # of Input/

Name(s) Pins Output Function

I

IAD15:0 16

I/O

O

IDMA Port Address/Data Bus

A0

1

Address Pin for External I/O,

Program, Data or Byte Access

D23:8

16

I/O

Data I/O Pins for Program, Data

Byte and I/O Spaces

IWR

IRD

IAL

IS

1

I

IDMA Write Enable

IDMA Read Enable

IDMA Address Latch Pin

IDMA Select

SCLK0

I/O

I

RFS0

DR0

I/O

I

TFS0

DT0

SCLK1

I/O

O

I/O

O

I

IACK

O

IDMA Port Acknowledge Configur-

able in Mode D; Open Source

NOTE

In Host Mode, external peripheral addresses can be decoded using the A0,

CMS, PMS, DMS and IOMS signals.

RFS1/IRQ0 I/O

DR1/FI

TFS1/IRQ1 I/O

I

O

I

Terminating Unused Pin

The following table shows the recommendations for terminating

unused pins.

DT1/FO

EE

O

I

Float

EBR

I

Pin Terminations

EBG

ERESET

EMS

EINT

ECLK

ELIN

ELOUT

O

I

O

I

O

I

O

I

I/O

Hi-Z*

Caused

By

3-State Reset

Unused

Configuration

Name

(Z)

State

XTAL

CLKOUT

A13:1 or

IAD12:0

A0

D23:8

D7 or

IWR

I

O

I

O

Float

High (Inactive)

Float

High (Inactive)

Float

Low (Inactive)

Float

High (Inactive)

Float

O

O (Z)

I/O (Z)

O (Z)

I/O (Z)

I

Hi-Z

I

Hi-Z

I

Hi-Z

I

BR, EBR

IS

BR, EBR

NOTES

*Hi-Z = High Impedance.

1. If the CLKOUT pin is not used, turn it OFF.

2. If the Interrupt/Programmable Flag pins are not used, there are two options:

Option 1: When these pins are configured as INPUTS at reset and function

as interrupts and input flag pins, pull the pins High (inactive).

Option 2: Program the unused pins as OUTPUTS, set them to 1, and let

them float.

3. All bidirectional pins have three-stated outputs. When the pins is configured

as an output, the output is Hi-Z (high impedance) when inactive.

4. CLKIN, RESET, and PF3:0 are not included in the table because these pins

must be used.

D6 or

IRD

I/O (Z)

I

BR, EBR

D5 or

IAL

I/O (Z)

I

D4 or

IS

I/O (Z)

I

Hi-Z

I

Hi-Z

BR, EBR

Interrupts

D3 or

IACK

D2:0 or

IAD15:13

PMS

DMS

BMS

IOMS

I/O (Z)

The interrupt controller allows the processor to respond to the

eleven possible interrupts and RESET with minimum overhead.

The AD73422 provides four dedicated external interrupt

input pins, IRQ2, IRQL0, IRQL1 and IRQE. In addition,

SPORT1 may be reconfigured for IRQ0, IRQ1, FLAG_IN

and FLAG_OUT, for a total of six external interrupts. The

AD73422 also supports internal interrupts from the timer, the

byte DMA port, the two serial ports, software and the power-

down control circuit. The interrupt levels are internally priori-

tized and individually maskable (except power-down and reset).

I/O (Z)

O (Z)

Hi-Z

O

BR, EBR

IS

BR, EBR

Float

O

REV. 0

–23–

AD73422

The IRQ2, IRQ0 and IRQ1 input pins can be programmed to

be either level- or edge-sensitive. IRQL0 and IRQL1 are level-

sensitive and IRQE is edge-sensitive. The priorities and vector

addresses of all interrupts are shown in Table XX.

Power-Down

The AD73422 processor has a low power feature that lets the

processor enter a very low power dormant state through hard-

ware or software control. Here is a brief list of power-down

features. Refer to the ADSP-2100 Family User’s Manual, Third

Edition, “System Interface” chapter, for detailed information

about the power-down feature.

Table XX. Interrupt Priority and Interrupt Vector Addresses

Interrupt Vector

Source of Interrupt

Address (Hex)

•

Quick recovery from power-down. The processor begins

executing instructions in as few as 400 CLKIN cycles.

RESET (or Power-Up with PUCR = 1) 0000 (Highest Priority)

Power-Down (Nonmaskable)

IRQ2

IRQL1

002C

0004

0008

000C

0010

0014

0018

001C

•

Support for an externally generated TTL or CMOS proces-

sor clock. The external clock can continue running during

power-down without affecting the 400 CLKIN cycle recovery.

IRQL0

•

Support for crystal operation includes disabling the oscillator

to save power (the processor automatically waits 4096 CLKIN

cycles for the crystal oscillator to start and stabilize), and

letting the oscillator run to allow 400 CLKIN cycle start up.

SPORT0 Transmit

SPORT0 Receive

IRQE

BDMA Interrupt

SPORT1 Transmit or IRQ1

SPORT1 Receive or IRQ0

Timer

0020

0024

Power-down is initiated by either the power-down pin (PWD)

or the software power-down force bit. Interrupt support

allows an unlimited number of instructions to be executed

before optionally powering down. The power-down interrupt

also can be used as a nonmaskable, edge-sensitive interrupt.

0028 (Lowest Priority)

Interrupt routines can either be nested with higher priority

interrupts taking precedence or processed sequentially. Inter-

rupts can be masked or unmasked with the IMASK register.

Individual interrupt requests are logically ANDed with the bits

in IMASK; the highest priority unmasked interrupt is then

selected. The power-down interrupt is nonmaskable.

•

Context clear/save control allows the processor to continue

where it left off or start with a clean context when leaving the

power-down state.

•

The RESET pin also can be used to terminate power-down.

Power-down acknowledge pin indicates when the processor

has entered power-down.

The AD73422 masks all interrupts for one instruction cycle

following the execution of an instruction that modifies the

IMASK register. This does not affect serial port autobuffering

or DMA transfers.

Idle

When the AD73422 is in the Idle Mode, the processor waits

indefinitely in a low power state until an interrupt occurs. When

an unmasked interrupt occurs, it is serviced; execution then

continues with the instruction following the IDLE instruction.

In Idle Mode IDMA, BDMA and autobuffer cycle steals still

occur.

The interrupt control register, ICNTL, controls interrupt nest-

ing and defines the IRQ0, IRQ1 and IRQ2 external interrupts to

be either edge- or level-sensitive. The IRQE pin is an external

edge-sensitive interrupt and can be forced and cleared. The

IRQL0 and IRQL1 pins are external level-sensitive interrupts.

Slow Idle

The IFC register is a write-only register used to force and clear

interrupts. On-chip stacks preserve the processor status and are

automatically maintained during interrupt handling. The stacks

are twelve levels deep to allow interrupt, loop and subroutine

nesting. The following instructions allow global enable or dis-

able servicing of the interrupts (including power-down), regard-

less of the state of IMASK. Disabling the interrupts does not

affect serial port autobuffering or DMA.

The IDLE instruction on the AD73422 slows the processor’s

internal clock signal, further reducing power consumption. The

reduced clock frequency, a programmable fraction of the normal

clock rate, is specified by a selectable divisor given in the IDLE

instruction. The format of the instruction is

IDLE (n);

where n = 16, 32, 64 or 128. This instruction keeps the proces-

sor fully functional, but operating at the slower clock rate. While

it is in this state, the processor’s other internal clock signals,

such as SCLK, CLKOUT and timer clock, are reduced by the

same ratio. The default form of the instruction, when no clock

divisor is given, is the standard IDLE instruction.

ENA INTS;

DIS INTS;

When the processor is reset, interrupt servicing is enabled.

LOW POWER OPERATION

The AD73422 has three low power modes that significantly

reduce the power dissipation when the device operates under

standby conditions. These modes are:

When the IDLE (n) instruction is used, it effectively slows

down the processor’s internal clock and thus its response time to

incoming interrupts. The one-cycle response time of the stan-

dard idle state is increased by n, the clock divisor. When an

enabled interrupt is received, the AD73422 will remain in the

idle state for up to a maximum of n processor cycles (n = 16, 32,

64 or 128) before resuming normal operation.

• Power-Down

• Idle

• Slow Idle

The CLKOUT pin may also be disabled to reduce external

power dissipation.

–24–

REV. 0

AD73422

When the IDLE (n) instruction is used in systems that have an

externally generated serial clock (SCLK), the serial clock rate

may be faster than the processor’s reduced internal clock rate.

Under these conditions, interrupts must not be generated at a

faster rate than can be serviced, due to the additional time the

processor takes to come out of the idle state (a maximum of n

processor cycles).

FULL MEMORY MODE

AD73422

14

24

A

13-0

1/2x CLOCK

OR

CLKIN

XTAL

ADDR13-0

D

23-16

A0-A21

BYTE

CRYSTAL

D

MEMORY

15-8

FL0-2

PF3

DATA

DATA23-0

BMS

CS

IRQ2/PF7

IRQE/PF4

IRQL0/PF5

IRQL1/PF6

A

10-0

ADDR

WR

RD

I/O SPACE

(PERIPHERALS)

D

23-8

SYSTEM INTERFACE

MODE C/PF2

MODE B/PF1

MODE A/PF0

DATA

CS

2048

LOCATIONS

Figure 13 shows a typical basic system configuration with the

AD73422, two serial devices, a byte-wide EPROM, and

optional external program and data overlay memories (mode

selectable). Programmable wait state generation allows the

processor to connect easily to slow peripheral devices. The

AD73422 also provides four external interrupts and two serial

ports or six external interrupts and one serial port. Host Memory

Mode allows access to the full external data bus, but limits

addressing to a single address bit (A0). Additional system periph-

erals can be added in this mode through the use of external

hardware to generate and latch address signals.

IOMS

A

13-0

23-0

SPORT1

SCLK1

OVERLAY

MEMORY

ADDR

DATA

D

AFE*

SECTION

OR

SERIAL

DEVICE

RFS1 OR IRQ0

TFS1 OR IRQ1

DT1 OR FO

DR1 OR FI

TWO 8K

PM SEGMENTS

PMS

DMS

CMS

TWO 8K

DM SEGMENTS

SPORT0

BR

BG

BGH

SCLK0

RFS0

TFS0

DT0

AFE*

SECTION

OR

SERIAL

DEVICE

DR0

PWD

PWDACK

HOST MEMORY MODE

AD73422

Clock Signals

1

The AD73422 can be clocked by either a crystal or a TTL-

compatible clock signal.

1/2x CLOCK

OR

CRYSTAL

CLKIN

A0

16

XTAL

DATA23-8

FL0-2

PF3

The CLKIN input cannot be halted, changed during operation

or operated below the specified frequency during normal opera-

tion. The only exception is while the processor is in the power-

down state. For additional information, refer to Chapter 9,

ADSP-2100 Family User’s Manual, Third Edition, for detailed

information on this power-down feature.

BMS

IRQ2/PF7

IRQE/PF4

IRQL0/PF5

IRQL1/PF6

MODE C/PF2

MODE B/PF1

MODE A/PF0

WR

RD

If an external clock is used, it should be a TTL-compatible

signal running at half the instruction rate. The signal is con-

nected to the processor’s CLKIN input. When an external clock

is used, the XTAL input must be left unconnected.

SPORT1

SCLK1

RFS1 OR IRQ0

TFS1 OR IRQ1

DT1 OR FO

DR1 OR FI

IOMS

AFE*

SECTION

OR

SERIAL

DEVICE

PMS

DMS

CMS

SPORT0

The AD73422 uses an input clock with a frequency equal to

half the instruction rate; a 26.00 MHz input clock yields a 19 ns

processor cycle (which is equivalent to 52 MHz). Normally,

instructions are executed in a single processor cycle. All device

timing is relative to the internal instruction clock rate, which is

indicated by the CLKOUT signal when enabled.

BR

BG

BGH

SCLK0

RFS0

TFS0

DT0

AFE*

SECTION

OR

SERIAL

DEVICE

DR0

PWD

PWDACK

IDMA PORT

IRD/D6

IWR/D7

IS/D4

IAL/D5

IACK/D3

SYSTEM

INTERFACE

OR

*AFE SECTION CAN BE

CONNECTED TO EITHER

SPORT0 OR SPORT1

Because the AD73422 includes an on-chip oscillator circuit, an

external crystal may be used. The crystal should be connected

across the CLKIN and XTAL pins, with two capacitors con-

nected as shown in Figure 14. Capacitor values are dependent

on crystal type and should be specified by the crystal manufacturer.

A parallel-resonant, fundamental frequency, microprocessor-

grade crystal should be used.

␮CONTROLLER

16

IAD15-0

Figure 13. Basic System Configuration

A clock output (CLKOUT) signal is generated by the processor

at the processor’s cycle rate. This can be enabled and disabled

by the CLK0DIS bit in the SPORT0 Autobuffer Control Register.

CLKIN

XTAL

CLKOUT

DSP

Figure 14. External Crystal Connections

REV. 0

–25–

AD73422

Reset

Setting Memory Mode

The RESET signal initiates a master reset of the AD73422. The

RESET signal must be asserted during the power-up sequence

to assure proper initialization. RESET during initial power-up

must be held long enough to allow the internal clock to stabilize.

If RESET is activated any time after power-up, the clock con-

tinues to run and does not require stabilization time.

Memory Mode selection for the AD73422 is made during chip

reset through the use of the Mode C pin. This pin is multi-

plexed with the DSP’s PF2 pin, so care must be taken in how

the mode selection is made. The two methods for selecting the

value of Mode C are active and passive.

Passive configuration involves the use a pull-up or pull-down

resistor connected to the Mode C pin. To minimize power

consumption, or if the PF2 pin is to be used as an output in the

DSP application, a weak pull-up or pull-down, on the order of

100 kΩ, can be used. This value should be sufficient to pull the

pin to the desired level and still allow the pin to operate as

a programmable flag output without undue strain on the

processor’s output driver. For minimum power consumption

during power-down, reconfigure PF2 to be an input, as the pull-

up or pull-down will hold the pin in a known state and will not

switch.

The power-up sequence is defined as the total time required for

the crystal oscillator circuit to stabilize after a valid V_DDis ap-

plied to the processor, and for the internal phase-locked loop

(PLL) to lock onto the specific crystal frequency. A minimum of

2000 CLKIN cycles ensures that the PLL has locked, but does

not include the crystal oscillator start-up time. During this power-

up sequence the RESET signal should be held low. On any

subsequent resets, the RESET signal must meet the minimum

pulsewidth specification, t_RSP

.

The RESET input contains some hysteresis; however, if an

RC circuit is used to generate the RESET signal, an external

Schmidt trigger is recommended.

Active configuration involves the use of a three-statable exter-

nal driver connected to the Mode C pin. A driver’s output en-

able should be connected to the DSP’s RESET signal such that

it only drives the PF2 pin when RESET is active (low). When

RESET is deasserted, the driver should three-state, thus allow-

ing full use of the PF2 pin as either an input or output. To

minimize power consumption during power-down, configure

the programmable flag as an output when connected to a three-

stated buffer. This ensures that the pin will be held at a constant

level and not oscillate should the three-state driver’s level hover

around the logic switching point.

The master reset sets all internal stack pointers to the empty

stack condition, masks all interrupts and clears the MSTAT

register. When RESET is released, if there is no pending bus

request and the chip is configured for booting, the boot-loading

sequence is performed. The first instruction is fetched from on-

chip program memory location 0x0000 once boot loading com-

pletes.

MODES OF OPERATION

Table XXI summarizes the AD73422 memory modes.

Table XXI. Modes of Operations¹

MODE C²MODE B³MODE A⁴Booting Method

0

1

0

1

0

1

BDMA feature is used to load the first 32 program memory words from the byte memory

space. Program execution is held off until all 32 words have been loaded. Chip is configured

in Full Memory Mode.⁵

No Automatic boot operations occur. Program execution starts at external memory location

0. Chip is configured in Full Memory Mode. BDMA can still be used, but the processor does

not automatically use or wait for these operations.

BDMA feature is used to load the first 32 program memory words from the byte memory

space. Program execution is held off until all 32 words have been loaded. Chip is config-

ured in Host Mode. (REQUIRES ADDITIONAL HARDWARE.)

IDMA feature is used to load any internal memory as desired. Program execution is held off

until internal program memory location 0 is written to. Chip is configured in Host Mode.⁵

1

NOTES

¹All mode pins are recognized while RESET is active (low).

²When Mode C = 0, Full Memory enabled. When Mode C = 1, Host Memory Mode enabled.

³When Mode B = 0, Auto Booting enabled. When Mode B = 1, no Auto Booting.

⁴When Mode A = 0, BDMA enabled. When Mode A = 1, IDMA enabled.

⁵Considered as standard operating settings. Using these configurations allows for easier design and better memory management.

–26–

REV. 0

AD73422

MEMORY ARCHITECTURE

DATA MEMORY

The AD73422 provides a variety of memory and peripheral

interface options. The key functional groups are Program

Memory, Data Memory, Byte Memory and I/O. Refer to the

following figures and tables for PM and DM memory alloca-

tions in the AD73422.

Data Memory (Full Memory Mode) is a 16-bit-wide space

used for the storage of data variables and for memory-mapped

control registers. The AD73422-80 has 16K words on Data

Memory RAM on chip (the AD73422-40 has 8K words on Data

Memory RAM on chip), consisting of 16,352 user-accessible

locations in the case of the AD73422-80 (8,160 user-accessible

locations in the case of the AD73422-40) and 32 memory-

mapped registers. Support also exists for up to two 8K external

memory overlay spaces through the external data bus. All inter-

nal accesses complete in one cycle. Accesses to external memory

are timed using the wait states specified by the DWAIT register.

PROGRAM MEMORY

Program Memory (Full Memory Mode) is a 24-bit-wide

space for storing both instruction op codes and data. The

AD73422-80 has 16K words of Program Memory RAM on chip

(the AD73422-40 has 8K words of Program Memory RAM on

chip), and the capability of accessing up to two 8K external

memory overlay spaces using the external data bus.

DATA MEMORY

ADDRESS

DATA MEMORY

32 MEMORY

MAPPED

0

x

3FFF

ALWAYS

Program Memory (Host Mode) allows access to all internal

memory. External overlay access is limited by a single external

address line (A0). External program execution is not available in

host mode due to a restricted data bus that is 16 bits wide only.

ACCESSIBLE

REGISTERS

0

x

3FE0

3FDF

AT ADDRESS

0x2000 – 0x3FFF

0

x

INTERNAL

8160

WORDS

INTERNAL

MEMORY

0

x

0000–

1FFF

0x

0

x

1FFF

2000

ACCESSIBLE WHEN

DMOVLAY = 0

0x

0

x

0000–

1FFF

8K INTERNAL

DMOVLAY = 0

OR

EXTERNAL 8K

DMOVLAY = 1, 2

0x

Table XXII. PMOVLAY Bits

ACCESSIBLE WHEN

DMOVLAY = 1

0

x

0000–

1FFF

0x

EXTERNAL

MEMORY

0

x0000

ACCESSIBLE WHEN

DMOVLAY = 2

PMOVLAY Memory A13

A12:0

0

1

Internal

External

Overlay 1

Not Applicable Not Applicable

Figure 16. Data Memory Map

0

1

13 LSBs of Address

Between 0x2000

and 0x3FFF

13 LSBs of Address

Between 0x2000

and 0x3FFF

Data Memory (Host Mode) allows access to all internal memory.

External overlay access is limited by a single external address

line (A0). The DMOVLAY bits are defined in Table XXIII.

2

External

Overlay 2

Table XXIII. DMOVLAY Bits

DMOVLAY Memory A13

A12:0

1

PM (MODE B = 0)

PM (MODE B = 1)

0

1

Internal

Not Applicable Not Applicable

ALWAYS

RESERVED

ACCESSIBLE

AT ADDRESS

0x0000 – 0x1FFF

0x2000–

External

Overlay 1

0

1

13 LSBs of Address

Between 0x2000

and 0x3FFF

INTERNAL

MEMORY

0x3FFF

INTERNAL

MEMORY

ACCESSIBLE WHEN

PMOVLAY = 0

0x2000–

0x3FFF

0x0000–

0x1FFF

ACCESSIBLE WHEN

PMOVLAY = 0

2

0x2000–

0x3FFF

ACCESSIBLE WHEN

PMOVLAY = 0

2

External

Overlay 2

13 LSBs of Address

Between 0x2000

and 0x3FFF

ACCESSIBLE WHEN

PMOVLAY = 1

0x2000–

0x3FFF

EXTERNAL

MEMORY

RESERVED

2

EXTERNAL

MEMORY

ACCESSIBLE WHEN

PMOVLAY = 2

1

WHEN MODE B = 1, PMOVLAY MUST BE SET TO 0

SEE TABLE III FOR PMOVLAY BITS

2

I/O Space (Full Memory Mode)

The AD73422 supports an additional external memory space

called I/O space. This space is designed to support simple con-

nections to peripherals (such as data converters and external

registers) or to bus interface ASIC data registers. I/O space

supports 2048 locations of 16-bit wide data. The lower eleven

bits of the external address bus are used; the upper three bits are

undefined. Two instructions were added to the core ADSP-2100

Family instruction set to read from and write to I/O memory

space. The I/O space also has four dedicated 3-bit wait state

registers, IOWAIT0-3, that specify up to seven wait states to be

automatically generated for each of four regions. The wait states

act on address ranges as shown in Table XXIV.

PROGRAM MEMORY

MODE B = 0

MODE B = 1

ADDRESS

0x3FFF

8K INTERNAL

PMOVLAY = 0

OR

8K EXTERNAL

PMOVLAY = 1 OR 2

8K INTERNAL

PMOVLAY = 0

0x2000

0x1FFF

0x2000

0x1FFF

8K EXTERNAL

8K INTERNAL

0x0000

Figure 15. Program Memory Map

REV. 0

–27–

AD73422

Table XXIV. Wait States

Byte Memory DMA (BDMA, Full Memory Mode)

The Byte memory DMA controller allows loading and storing of

program instructions and data using the byte memory space.

The BDMA circuit is able to access the byte memory space

while the processor is operating normally, and steals only one

DSP cycle per 8-, 16- or 24-bit word transferred.

Address Range Wait State Register

0x000–0x1FF

0x200–0x3FF

0x400–0x5FF

0x600–0x7FF

IOWAIT0

IOWAIT1

IOWAIT2

IOWAIT3

BDMA CONTROL

15 14 13 12 11 10

9

8

7

6

5

0

4

0

3

1

2

0

1

0

DM (0

؋

3FE3)

Composite Memory Select (CMS)

The AD73422 has a programmable memory select signal that is

useful for generating memory select signals for memories mapped

to more than one space. The CMS signal is generated to have

the same timing as each of the individual memory select signals

(PMS, DMS, BMS, IOMS) but can combine their functionality.

BTYPE

BDIR

BMPAGE

0 = LOAD FROM BM

1 = STORE TO BM

BCR

0 = RUN DURING BDMA

1 = HALT DURING BDMA

Each bit in the CMSSEL register, when set, causes the CMS

signal to be asserted when the selected memory select is as-

serted. For example, to use a 32K word memory to act as both

program and data memory, set the PMS and DMS bits in the

CMSSEL register and use the CMS pin to drive the chip select

of the memory; use either DMS or PMS as the additional

address bit.

Figure 18. BDMA Control Register

The BDMA circuit supports four different data formats that are

selected by the BTYPE register field. The appropriate number

of 8-bit accesses are done from the byte memory space to build

the word size selected. Table XXV shows the data formats sup-

ported by the BDMA circuit.

The CMS pin functions like the other memory select signals,

with the same timing and bus request logic. A 1 in the enable bit

causes the assertion of the CMS signal at the same time as the

selected memory select signal. All enable bits default to 1 at

reset, except the BMS bit.

Table XXV. Data Formats

Internal

BTYPE

Memory Space

Word Size

Alignment

00

01

10

11

Program Memory

Data Memory

24

16

8

Full Word

MSBs

Boot Memory Select (BMS) Disable

The AD73422 also lets you boot the processor from one exter-

nal memory space while using a different external memory space

for BDMA transfers during normal operation. You can use the

CMS to select the first external memory space for BDMA trans-

fers and BMS to select the second external memory space for

booting. The BMS signal can be disabled by setting Bit 3 of the

System Control Register to 1. The System Control Register is

illustrated in Figure 17.

8

LSBs

Unused bits in the 8-bit data memory formats are filled with 0s.

The BIAD register field is used to specify the starting address

for the on-chip memory involved with the transfer. The 14-bit

BEAD register specifies the starting address for the external

byte memory space. The 8-bit BMPAGE register specifies the

starting page for the external byte memory space. The BDIR

register field selects the direction of the transfer. Finally the

14-bit BWCOUNT register specifies the number of DSP words

to transfer and initiates the BDMA circuit transfers.

SYSTEM CONTROL REGISTER

15 14 13 12 11 10

9

8

7

6

5

4

3

0

2

1

0

1

0

1

0

DM (0

؋

3FFF)

SPORT0 ENABLE

1 = ENABLED

0 = DISABLED

PWAIT

PROGRAM MEMORY

WAIT STATES

BDMA accesses can cross page boundaries during sequential

addressing. A BDMA interrupt is generated on the completion

of the number of transfers specified by the BWCOUNT register.

SPORT1 ENABLE

1 = ENABLED

0 = DISABLED

BMS ENABLE

0 = ENABLED

1 = DISABLED

SPORT1 CONFIGURE

1 = SERIAL PORT

0 = FI, FO, IRQ0,

The BWCOUNT register is updated after each transfer so it can

be used to check the status of the transfers. When it reaches

zero, the transfers have finished and a BDMA interrupt is gener-

ated. The BMPAGE and BEAD registers must not be accessed

by the DSP during BDMA operations.

IRQ1, SCLK

Figure 17. System Control Register

Byte Memory

The byte memory space is a bidirectional, 8-bit-wide, external

memory space used to store programs and data. Byte memory is

accessed using the BDMA feature. The BDMA Control Regis-

ter is shown in Figure 18. The byte memory space consists of

256 pages, each of which is 16K × 8.

The source or destination of a BDMA transfer will always be

on-chip program or data memory.

When the BWCOUNT register is written with a nonzero value,

the BDMA circuit starts executing byte memory accesses with

wait states set by BMWAIT. These accesses continue until the

count reaches zero. When enough accesses have occurred to

create a destination word, it is transferred to or from on-chip

memory. The transfer takes one DSP cycle. DSP accesses to exter-

nal memory have priority over BDMA byte memory accesses.

The byte memory space on the AD73422 supports read and

write operations as well as four different data formats. The byte

memory uses data bits 15:8 for data. The byte memory uses

data bits 23:16 and address bits 13:0 to create a 22-bit address.

This allows up to a 4 meg × 8 (32 megabit) ROM or RAM to be

used without glue logic. All byte memory accesses are timed by

the BMWAIT register.

–28–

REV. 0

AD73422

The BDMA Context Reset bit (BCR) controls whether or not

the processor is held off while the BDMA accesses are occur-

ring. Setting the BCR bit to 0 allows the processor to continue

operations. Setting the BCR bit to 1 causes the processor to

stop execution while the BDMA accesses are occurring, to clear

the context of the processor and start execution at address 0

when the BDMA accesses have completed.

Once an access has occurred, the latched address is automati-

cally incremented and another access can occur.

Through the IDMAA register, the DSP can also specify the

starting address and data format for DMA operation. Asserting

the IDMA port select (IS) and address latch enable (IAL) di-

rects the AD73422 to write the address onto the IAD0–14 bus

into the IDMA Control Register. If IAD[15] is set to 0, IDMA

latches the address. If IAD[15] is set to 1, IDMA latches OVLAY

memory. The IDMA OVLAY and address are stored in separate

memory-mapped registers. The IDMAA register, shown below,

is memory mapped at address DM (0x3FE0). Note that the

latched address (IDMAA) cannot be read back by the host. The

IDMA OVLAY register is memory mapped at address DM

(0x3FE7). See Figure 19 for more information on IDMA and

DMA memory maps.

The BDMA overlay bits specify the OVLAY memory blocks to

be accessed for internal memory.

Internal Memory DMA Port (IDMA Port; Host Memory

Mode)

The IDMA Port provides an efficient means of communication

between a host system and the AD73422. The port is used to

access the on-chip program memory and data memory of the

DSP with only one DSP cycle per word overhead. The IDMA

port cannot be used, however, to write to the DSP’s memory-

mapped control registers. A typical IDMA transfer process is

described as follows:

IDMA CONTROL (U = UNDEFINED AT RESET)

15 14 13 12 11 10

9

8

7

6

5

4

3

2

1

0

DM(0

؋

3FE0)

U

1. Host starts IDMA transfer.

IDMAA ADDRESS

2. Host checks IACK control line to see if the DSP is busy.

IDMAD

DESTINATION MEMORY TYPE:

3. Host uses IS and IAL control lines to latch either the DMA

starting address (IDMAA) or the PM/DM OVLAY selection

into the DSP’s IDMA control registers.

0 = PM

1 = DM

Figure 19. IDMA Control/OVLAY Registers

If IAD[15] = 1, the value of IAD[7:0] represents the IDMA

overlay: IAD[14:8] must be set to 0.

Bootstrap Loading (Booting)

The AD73422 has two mechanisms to allow automatic loading

of the internal program memory after reset. The method for

booting after reset is controlled by the Mode A, B and C con-

figuration bits.

If IAD[15] = 0, the value of IAD[13:0] represents the start-

ing address of internal memory to be accessed and IAD[14]

reflects PM or DM for access.

4. Host uses IS and IRD (or IWR) to read (or write) DSP inter-

When the mode pins specify BDMA booting, the AD73422

initiates a BDMA boot sequence when reset is released.

nal memory (PM or DM).

5. Host checks IACK line to see if the DSP has completed the

The BDMA interface is set up during reset to the following

defaults when BDMA booting is specified: the BDIR, BMPAGE,

BIAD and BEAD registers are set to 0, the BTYPE register is

set to 0 to specify program memory 24-bit words, and the

BWCOUNT register is set to 32. This causes 32 words of on-

chip program memory to be loaded from byte memory. These

32 words are used to set up the BDMA to load in the remaining

program code. The BCR bit is also set to 1, which causes pro-

gram execution to be held off until all 32 words are loaded into

on-chip program memory. Execution then begins at address 0.

previous IDMA operation.

6. Host ends IDMA transfer.

The IDMA port has a 16-bit multiplexed address and data bus

and supports 24-bit program memory. The IDMA port is

completely asynchronous and can be written to while the

AD73422 is operating at full speed.

The DSP memory address is latched and then automatically

incremented after each IDMA transaction. An external device

can, therefore, access a block of sequentially addressed memory

by specifying only the starting address of the block. This in-

creases throughput as the address does not have to be sent for

each memory access.

The ADSP-2100 Family Development Software (Revision 5.02

and later) fully supports the BDMA booting feature and can

generate byte memory space compatible boot code.

IDMA Port access occurs in two phases. The first is the IDMA

Address Latch cycle. When the acknowledge is asserted, a

14-bit address and 1-bit destination type can be driven onto the

bus by an external device. The address specifies an on-chip

memory location; the destination type specifies whether it is a

DM or PM access. The falling edge of the address latch signal

latches this value into the IDMAA register.

The IDLE instruction can also be used to allow the processor to

hold off execution while booting continues through the BDMA

interface. For BDMA accesses while in Host Mode, the ad-

dresses to boot memory must be constructed externally to the

AD73422. The only memory address bit provided by the pro-

cessor is A0.

IDMA Port Booting

Once the address is stored, data can either be read from or

written to the AD73422’s on-chip memory. Asserting the

select line (IS) and the appropriate read or write line (IRD and

IWR respectively) signals the AD73422 that a particular trans-

action is required. In either case, there is a one-processor-cycle

delay for synchronization. The memory access consumes one

additional processor cycle.

The AD73422 can also boot programs through its Internal

DMA port. If Mode C = 1, Mode B = 0 and Mode A = 1, the

AD73422 boots from the IDMA port. IDMA feature can load

as much on-chip memory as desired. Program execution is held

off until on-chip program memory location 0 is written to.

REV. 0

–29–

AD73422

Bus Request and Bus Grant (Full Memory Mode)

The AD73422 can relinquish control of the data and address

buses to an external device. When the external device requires

access to memory, it asserts the bus request (BR) signal. If the

AD73422 is not performing an external memory access, it re-

sponds to the active BR input in the following processor cycle

by:

•

Every instruction assembles into a single, 24-bit word that

can execute in a single instruction cycle.

The syntax is a superset ADSP-2100 Family assembly language

and is completely source and object code compatible with other

family members. Programs may need to be relocated to utilize

on-chip memory and conform to the AD73422’s interrupt

vector and reset vector map.

•

three-stating the data and address buses and the PMS, DMS,

BMS, CMS, IOMS, RD, WR output drivers,

•

Sixteen condition codes are available. For conditional jump,

call, return or arithmetic instructions, the condition can be

checked and the operation executed in the same instruction

cycle.

•

asserting the bus grant (BG) signal and

halting program execution.

If Go Mode is enabled, the AD73422 will not halt program

execution until it encounters an instruction that requires an

external memory access.

Multifunction instructions allow parallel execution of an

arithmetic instruction with up to two fetches or one write to

processor memory space during a single instruction cycle.

If the AD73422 is performing an external memory access when

the external device asserts the BR signal, it will not three-state

the memory interfaces or assert the BG signal until the proces-

sor cycle after the access completes. The instruction does not

need to be completed when the bus is granted. If a single in-

struction requires two external memory accesses, the bus will be

granted between the two accesses.

DESIGNING AN EZ-ICE-COMPATIBLE SYSTEM

The AD73422 has on-chip emulation support and an ICE-Port,

a special set of pins that interface to the EZ-ICE. These features

allow in-circuit emulation without replacing the target system

processor by using only a 14-pin connection from the target

system to the EZ-ICE. Target systems must have a 14-pin con-

nector to accept the EZ-ICE’s in-circuit probe, a 14-pin plug.

See the ADSP-2100 Family EZ-Tools data sheet for complete

information on ICE products.

When the BR signal is released, the processor releases the BG

signal, reenables the output drivers and continues program

execution from the point at which it stopped.

Issuing the chip reset command during emulation causes the

DSP to perform a full chip reset, including a reset of its memory

mode. Therefore, it is vital that the mode pins are set correctly

prior to issuing a chip reset command from the emulator user

interface. If you are using a passive method of maintaining

mode information (as discussed in Setting Memory Modes), it

does not matter that the mode information is latched by an

emulator reset. However, if you are using the RESET pin as a

method of setting the value of the mode pins, you have to take

the effects of an emulator reset into consideration.

The bus request feature operates at all times, including when

the processor is booting and when RESET is active.

The BGH pin is asserted when the AD73422 is ready to execute

an instruction, but is stopped because the external bus is already

granted to another device. The other device can release the bus

by deasserting bus request. Once the bus is released, the

AD73422 deasserts BG and BGH and executes the external

memory access.

Flag I/O Pins

The AD73422 has eight general-purpose programmable input/

output flag pins. They are controlled by two memory mapped

registers. The PFTYPE register determines the direction, 1 =

output and 0 = input. The PFDATA register is used to read and

write the values on the pins. Data being read from a pin config-

ured as an input is synchronized to the AD73422’s clock. Bits

that are programmed as outputs will read the value being out-

put. The PF pins default to input during reset.

One method of ensuring that the values located on the mode

pins are those desired is to construct a circuit like the one shown

in Figure 20. This circuit forces the value located on the Mode

A pin to logic high; regardless if it latched via the RESET or

ERESET pin.

ERESET

RESET

In addition to the programmable flags, the AD73422 has

five fixed-mode flags, FLAG_IN, FLAG_OUT, FL0, FL1

and FL2. FL0–FL2 are dedicated output flags. FLAG_IN and

FLAG_OUT are available as an alternate configuration of

SPORT1.

AD73422

1k⍀

MODE A/PFO

PROGRAMMABLE

I/O

Figure 20. Mode A Pin/EZ-ICE Circuit

Note: Pins PF0, PF1, PF2 and PF3 are also used for device

configuration during reset.

The ICE-Port interface consists of the following AD73422 pins:

EBR

EMS

ELIN

EBG

EINT

ELOUT

ERESET

ECLK

EE

INSTRUCTION SET DESCRIPTION

The AD73422 assembly language instruction set has an alge-

braic syntax that was designed for ease of coding and readabil-

ity. The assembly language, which takes full advantage of the

processor’s unique architecture, offers the following benefits:

These AD73422 pins must be connected only to the EZ-ICE

connector in the target system. These pins have no function

except during emulation, and do not require pull-up or pull-

down resistors. The traces for these signals between the AD73422

and the connector must be kept as short as possible, no longer

than three inches.

•

The algebraic syntax eliminates the need to remember cryp-

tic assembler mnemonics. For example, a typical arithmetic

add instruction, such as AR = AX0 + AY0, resembles a

simple equation.

–30–

REV. 0

AD73422

The following pins are also used by the EZ-ICE:

BR BG

RESET GND

Note: If your target does not meet the worst case chip specifica-

tion for memory access parameters, you may not be able to

emulate your circuitry at the desired CLKIN frequency. De-

pending on the severity of the specification violation, you may

have trouble manufacturing your system as DSP components

statistically vary in switching characteristic and timing require-

ments within published limits.

The EZ-ICE uses the EE (emulator enable) signal to take con-

trol of the AD73422 in the target system. This causes the pro-

cessor to use its ERESET, EBR and EBG pins instead of the

RESET, BR and BG pins. The BG output is three-stated. These

signals do not need to be jumper-isolated in your system.

Restriction: All memory strobe signals on the AD73422 (RD,

WR, PMS, DMS, BMS, CMS and IOMS) used in your target

system must have 10 kΩ pull-up resistors connected when the

EZ-ICE is being used. The pull-up resistors are necessary be-

cause there are no internal pull-ups to guarantee their state

during prolonged three-state conditions resulting from typical

EZ-ICE debugging sessions. These resistors may be removed at

your option when the EZ-ICE is not being used.

The EZ-ICE connects to your target system via a ribbon cable

and a 14-pin female plug. The ribbon cable is 10 inches in length

with one end fixed to the EZ-ICE. The female plug is plugged

onto the 14-pin connector (a pin strip header) on the target

board.

Target Board Connector for EZ-ICE Probe

The EZ-ICE connector (a standard pin strip header) is shown in

Figure 21. You must add this connector to your target board

design if you intend to use the EZ-ICE. Be sure to allow enough

room in your system to fit the EZ-ICE probe onto the 14-pin

connector.

Target System Interface Signals

When the EZ-ICE board is installed, the performance on some

system signals changes. Design your system to be compatible

with the following system interface signal changes introduced by

the EZ-ICE board:

•

EZ-ICE emulation introduces an 8 ns propagation delay

between your target circuitry and the DSP on the RESET

signal.

1

3

5

2

4

BG

GND

EBG

EBR

•

EZ-ICE emulation introduces an 8 ns propagation delay

between your target circuitry and the DSP on the BR signal.

BR

6

EINT

ELIN

EZ-ICE emulation ignores RESET and BR when single-

stepping.

7

؋

8

KEY (NO PIN)

ELOUT

EZ-ICE emulation ignores RESET and BR when in Emula-

tor Space (DSP halted).

10

12

14

9

ECLK

EZ-ICE emulation ignores the state of target BR in certain

modes. As a result, the target system may take control of the

DSP’s external memory bus only if bus grant (BG) is asserted

by the EZ-ICE board’s DSP.

11

13

EMS

EE

RESET

ERESET

TOP VIEW

ANALOG FRONT END (AFE) INTERFACING

Figure 21. Target Board Connector for EZ-ICE

The AFE section of the AD73422 features two voiceband input/

output channels, each with 16-bit linear resolution. Connectiv-

ity to the AFE section from the DSP is uncommitted, thus

allowing the user the flexibility of connecting in the mode or

configuration of their choice. This section will detail several

configurations—with no extra AFE channels configured and

with two extra AFE channels configured (using an external

AD73322 dual AFE).

The 14-pin, 2-row pin strip header is keyed at the Pin 7 loca-

tion—you must remove Pin 7 from the header. The pins must

be 0.025 inch square and at least 0.20 inch in length. Pin spac-

ing should be 0.1 × 0.1 inches. The pin strip header must have

at least 0.15 inch clearance on all sides to accept the EZ-ICE

probe plug.

Pin strip headers are available from vendors such as 3M,

McKenzie and Samtec.

DSP SPORT to AFE Interfacing

Target Memory Interface

The SCLK, SDO, SDOFS, SDI and SDIFS pins of SPORT2

must be connected to the Serial Clock, Receive Data, Receive

Data Frame Sync, Transmit Data and Transmit Data Frame

Sync pins respectively of either SPORT0 or SPORT1. The SE

pin may be controlled from a parallel output pin or flag pin such

as FL0-2 or, where SPORT2 power-down is not required, it can

be permanently strapped high using a suitable pull-up resistor.

The ARESET pin may be connected to the system hardware

reset structure or it may also be controlled using a dedicated

control line. In the event of tying it to the global system reset, it

is advisable to operate the device in mixed mode, which allows a

software reset, otherwise there is no convenient way of resetting

the AFE section.

For your target system to be compatible with the EZ-ICE emu-

lator, it must comply with the memory interface guidelines listed

below.

PM, DM, BM, IOM and CM

Design your Program Memory (PM), Data Memory (DM),

Byte Memory (BM), I/O Memory (IOM) and Composite

Memory (CM) external interfaces to comply with worst case

device timing requirements and switching characteristics as speci-

fied in the DSP’s data sheet. The performance of the EZ-ICE

may approach published worst case specification for some memory

access timing requirements and switching characteristics.

REV. 0

–31–

AD73422

TFS

DT

SDIFS

SDI

TFS

DT

SDIFS

SDI

AMCLK

SE

SCLK

DR

SCLK

AFE

DSP

SCLK

DR

SCLK

SECTION

ARESET

SDO

AD73422

AFE

SECTION

SDO

SDOFS

ARESET

SE

DSP

SECTION

DEVICE 1

RFS

SDOFS

RFS

FL0

FL1

FL0

FL1

SDIFS

SDI

AMCLK

SE

ADDITIONAL

AD73322

CODEC

Figure 22. AD73422 AFE to DSP Connection

Cascade Operation

SCLK

SDO

ARESET

DEVICE 2

Where it is required to configure extra analog I/O channels to

the existing two channels on the AD73422, it is possible to

cascade up to six more channels (using single channel AD73311

or dual channel AD73322 AFEs) by using the scheme described

in Figure 24. It is necessary, however, to ensure that the timing

of the SE and ARESET signals is synchronized at each device in

the cascade. A simple D-type flip-flop is sufficient to sync each

signal to the master clock AMCLK, as in Figure 23.

SDOFS

D1

D2

Q1

Q2

74HC74

Figure 24. Connection of an AD73322 Cascaded to

AD73422

SE SIGNAL

SYNCHRONIZED

TO AMCLK

DSP

CONTROL

TO SE

Interfacing to the AFE’s Analog Inputs and Outputs

The AFE section of the AD73422 offers a flexible interface for

microphone pickups, line level signals or PSTN line interfaces.

This section will detail some of the configurations that can be

used with the input and output sections.

D

Q

1/2

74HC74

CLK

AMCLK

ARESET SIGNAL

SYNCHRONIZED

TO AMCLK

DSP

CONTROL

TO ARESET

D

Q

1/2

74HC74

The AD73422 features both differential inputs and outputs on

each channel to provide optimal performance and avoid common-

mode noise. It is also possible to interface either inputs or out-

puts in single-ended mode. This section details the choice of

input and output configurations and also gives some tips toward

successful configuration of the analog interface sections.

CLK

AMCLK

Figure 23. SE and ARESET Sync Circuit for Cascaded

Operation

Connection of a cascade of devices to a DSP, as shown in Fig-

ure 24, is no more complicated than connecting a single device.

Instead of connecting the SDO and SDOFS to the DSP’s Rx

port, these are now daisy-chained to the SDI and SDIFS of the

next device in the cascade. The SDO and SDOFS of the final

device in the cascade are connected to the DSP section’s Rx

port to complete the cascade. SE and ARESET on all devices

are fed from the signals that were synchronized with the AMCLK

using the circuit as described above. The SCLK from only one

device need be connected to the DSP section’s SCLK input(s)

as all devices will be running at the same SCLK frequency and

phase.

ANTIALIAS

FILTER

100⍀

VFBN1

VINN1

0.047␮F

V

REF

VINP1

0.047␮F

100⍀

0/38dB

PGA

VFBP1

V

REF

GAIN

1

AD73422

VOUTP1

VOUTN1

CONTINUOUS

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

REFOUT

REFCAP

0.1␮F

REFERENCE

Figure 25. Analog Input (DC-Coupled)

–32–

REV. 0

AD73422

Analog Inputs

There are several different ways in which the analog input (en-

coder) section of the AD73422 can be interfaced to external

circuitry. It provides optional input amplifiers which allows

sources with high source impedance to drive the ADC section

correctly. When the input amplifiers are enabled, the input

channel is configured as a differential pair of inverting amplifiers

referenced to the internal reference (REFCAP) level. The in-

verting terminals of the input amplifier pair are designated as

pins VINP1 and VINN1 for Channel 1 (VINP2 and VINN2 for

Channel 2) and the amplifier feedback connections are available

on pins VFBP1 and VFBN1 for Channel 1 (VFBP2 and VFBN2

for Channel 2).

ANTIALIAS

FILTER

100⍀

VFBN1

VINN1

0.047␮F

V

REF

0.047␮F

100⍀

VINP1

0/38dB

PGA

VFBP1

V

REF

GAIN

1

For applications where external signal buffering is required, the

input amplifiers can be bypassed and the ADC driven directly.

When the input amplifiers are disabled, the sigma-delta mod-

ulator’s input section (SC PGA) is accessed directly through the

VFBP1 and VFBN1 pins for Channel 1 (VFBP2 and VFBN2

for Channel 2).

AD73422

VOUTP1

CONTINUOUS

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

VOUTN1

REFOUT

OPTIONAL

BUFFER

REFERENCE

It is also possible to drive the ADCs in either differential or

single-ended modes. If the single-ended mode is chosen it is

possible using software control to multiplex between two single-

ended inputs connected to the positive and negative input pins.

REFCAP

0.1␮F

Figure 26. Analog Input (DC-Coupled) Using External

Amplifiers

The primary concerns in interfacing to the ADC are firstly to

provide adequate antialias filtering and to ensure that the signal

source will correctly drive the switched-capacitor input of the

ADC. The sigma-delta design of the ADC and its oversampling

characteristics simplify the antialias requirements, but it must be

remembered that the single-pole RC filter is primarily intended

to eliminate aliasing of frequencies above the Nyquist fre-

quency of the sigma-delta modulator’s sampling rate (typi-

cally 2.048 MHz). It may still require a more specific digital

filter implementation in the DSP to provide the final signal

frequency response characteristics. It is recommended that for

optimum performance the capacitors used for the antialiasing

filter be of high quality dielectric (NPO). The second issue

mentioned above is interfacing the signal source to the ADC’s

switched capacitor input load. The SC input presents a complex

dynamic load to a signal source, so it is important to understand

that the slew rate characteristic is an important consideration

when choosing external buffers for use with the AD73422. The

internal inverting op amps on the AD73422’s AFE are specifi-

cally designed to interface to the ADC’s SC input stage.

The AD73422’s ADC inputs are biased about the internal refer-

ence level (REFCAP level), therefore it may be necessary to

either bias external signals to this level using the buffered

REFOUT level as the reference. This is applicable in either dc-

or ac-coupled configurations. In the case of dc-coupling, the

signal (biased to REFOUT) may be applied directly to the in-

puts (using amplifier bypass), as shown in Figure 25, or it may

be conditioned in an external op amp where it can also be bi-

ased to the reference level using the buffered REFOUT signal as

shown in Figure 26. It is also possible to connect inputs directly

to the AD73422’s input op amps as shown in Figure 27.

100pF

50k⍀

VFBN1

VINN1

50k⍀

V

REF

VINP1

0/38dB

PGA

The AD73422’s on-chip 38 dB preamplifier can be enabled

when there is not enough gain in the input circuit; the preampli-

fier is configured by bits IGS0–2 of CRD. The total gain must

be configured to ensure that a full-scale input signal produces a

signal level at the input to the sigma-delta modulator of the

ADC that does not exceed the maximum input range.

50k⍀

VFBP1

100pF

V

REF

GAIN

1

AD73422

The dc biasing of the analog input signal is accomplished with

an on-chip voltage reference. If the input signal is not biased at

the internal reference level (via REFOUT), it must be ac-coupled

with external coupling capacitors. C_INshould be 0.1 µF or

larger. The dc biasing of the input can then be accomplished

using resistors to REFOUT as in Figures 28 and 29.

VOUTP1

CONTINUOUS

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

VOUTN1

REFOUT

REFCAP

0.1␮F

REFERENCE

Figure 27. Analog Input (DC-Coupled) Using Internal

Amplifiers

REV. 0

–33–

AD73422

In the case of ac-coupling, a capacitor is used to couple the

signal to the input of the ADC. The ADC input must be biased

to the internal reference (REFCAP) level, which is done by

connecting the input to the REFOUT pin through a 10 kΩ

resistor as shown in Figure 28.

If best performance is required from a single-ended source, it is

possible to configure the AD73422’s input amplifiers as a

single-ended-to-differential converter as shown in Figure 30.

100pF

50k⍀

VFBN1

VINN1

0.1␮F

100⍀

VFBN1

VINN1

0.047␮F

V

REF

V

REF

50k⍀

VINP1

10k⍀

0.1␮F

0/38dB

PGA

VINP1

50k⍀

VFBP1

0/38dB

PGA

100⍀

VFBP1

100pF

0.047␮F

10k⍀

V

REF

V

GAIN

1

REF

GAIN

1

AD73422

VOUTP1

CONTINUOUS

TIME

LOW-PASS

FILTER

VOUTP1

+6/–15dB

PGA

CONTINUOUS

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

VOUTN1

REFOUT

REFCAP

0.1␮F

REFERENCE

REFCAP

0.1␮F

Figure 30. Single-Ended-to-Differential Conversion On

Analog Input

Figure 28. Analog Input (AC-Coupled) Differential

If the ADC is being connected in single-ended mode, the

AD73422 should be programmed for single-ended mode using

the SEEN and INV bits of CRF and the inputs connected as

shown in Figure 29. When operated in single-ended input

mode, the AD73422 can multiplex one of the two inputs to the

ADC input.

Interfacing to an Electret Microphone

Figure 31 details an interface for an electret microphone which

may be used in some voice applications. Electret microphones

typically feature a FET amplifier whose output is accessed on

the same lead that supplies power to the microphone, therefore

this output signal must be capacitively coupled to remove the

power supply (dc) component. In this circuit the AD73422

0.1␮F

100⍀

VFBN1

VINN1

+5V

0.047␮F

R

A

V

REF

10␮F

10k⍀

C1

R2

VINP1

0/38dB

PGA

VFBN1

VINN1

VFBP1

C2

R

B

R1

V

REF

V

ELECTRET

PROBE

REF

VINP1

GAIN

1

0/38dB

PGA

AD73422

VFBP1

VOUTP1

CONTINUOUS

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

V

REF

GAIN

1

VOUTN1

REFOUT

AD73422

REFERENCE

VOUTP1

CONTINUOUS

REFCAP

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

0.1␮F

VOUTN1

REFOUT

REFCAP

Figure 29. Analog Input (AC-Coupled) Single-Ended

REFERENCE

C

REFCAP

Figure 31. Electret Microphone Interface Circuit

–34–

REV. 0

AD73422

Figure 33 shows an example circuit for providing a single-ended

output with ac coupling. The capacitor of this circuit (C_OUT) is

not optional if dc current drain is to be avoided.

input channel is being used in single-ended mode where the

internal inverting amplifier provides suitable gain to scale the

input signal relative to the ADC’s full-scale input range. The

buffered internal reference level at REFOUT is used via an

external buffer to provide power to the electret microphone.

This provides a quiet, stable supply for the microphone. If this

is not a concern, then the microphone can be powered from the

system power supply.

VFBN1

VINN1

V

REF

Analog Output

VINP1

The AD73422’s differential analog output (VOUT) is produced

by an on-chip differential amplifier. The differential output can

be ac-coupled or dc-coupled directly to a load that can be a

headset or the input of an external amplifier (the specified

minimum resistive load on the output section is 150 Ω.) It is

possible to connect the outputs in either a differential or a

single-ended configuration, but please note that the effective

maximum output voltage swing (peak-to-peak) is halved in the

case of single-ended connection. Figure 32 shows a simple cir-

cuit providing a differential output with ac coupling. The ca-

pacitors in this circuit (C_OUT) are optional; if used, their value

can be chosen as follows:

VFBP1

GAIN

1

AD73422

C

OUT

VOUTP1

VOUTN1

CONTINUOUS

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

R

LOAD

REFOUT

REFCAP

0.1␮F

REFERENCE

1

C_OUT

=

2π f_CR_LOAD

Figure 33. Example Circuit for Single-Ended Output

where f_C= desired cutoff frequency.

Differential-to-Single-Ended Output

In some applications it may be desirable to convert the full

differential output of the decoder channel to a single-ended

signal. The circuit of Figure 34 shows a scheme for doing this.

VFBN1

VINN1

V

REF

VFBN1

VINN1

VINP1

0/38dB

PGA

VFBP1

V

REF

VINP1

V

REF

0/38dB

PGA

GAIN

1

VFBP1

AD73422

C

OUT

VOUTP1

VOUTN1

V

REF

CONTINUOUS

GAIN

1

TIME

LOW-PASS

FILTER

+6/–15dB

PGA

R

LOAD

AD73422

VOUTP1

C

OUT

CONTINUOUS

R

I

REFOUT

REFCAP

TIME

LOW-PASS

FILTER

REFERENCE

+6/–15dB

PGA

R

VOUTN1

F

R

I

C

REFCAP

R

F

REFOUT

R

LOAD

REFERENCE

REFCAP

Figure 32. Example Circuit for Differential Output

0.1␮F

Figure 34. Example Circuit for Differential-to-Single-

Ended Output Conversion

REV. 0

–35–

AD73422

Grounding and Layout

As the analog inputs to the AD73422’s AFE section are differ-

ential, most of the voltages in the analog modulator are common-

mode voltages. The excellent common-mode rejection of the

part will remove common-mode noise on these inputs. The

analog and digital supplies of the AD73422 are independent and

separately pinned out to minimize coupling between analog and

digital sections of the device. The digital filters on the encoder

section will provide rejection of broadband noise on the power

supplies, except at integer multiples of the modulator sampling

frequency. The digital filters also remove noise from the analog

inputs provided the noise source does not saturate the analog

modulator. However, because the resolution of the AD73422’s

ADC is high, and the noise levels from the AD73422 are so low,

care must be taken with regard to grounding and layout.

AFE DIGITAL

AFE ANALOG

DSP

7

6

5

4

3

2

1

A B C D

E F G H J K L M N P R T U

DIGITAL

GROUND PLANE

ANALOG

GROUND PLANE

The printed circuit board that houses the AD73422 should be

designed so the analog and digital sections are separated and

confined to certain sections of the board. The AD73422 ball-

out configuration offers a major advantage in that its analog

interfaces are confined to the last three rows of the package.

This facilitates the use of ground planes that can be easily sepa-

rated, as shown in Figure 35. A minimum etch technique is

generally best for ground planes as it gives the best shielding.

Digital and analog ground planes should be joined in only one

place. If this connection is close to the device, it is recommended

to use a ferrite bead inductor.

Figure 35. Ground Plane Layout

the analog inputs. Traces on opposite sides of the board should

run at right angles to each other. This will reduce the effects of

feedthrough through the board. A microstrip technique is by far

the best but is not always possible with a double-sided board. In

this technique, the component side of the board is dedicated to

ground planes while signals are placed on the other side.

Good decoupling is important when using high speed devices.

On the AD73422 both the reference (REFCAP) and supplies

need to be decoupled. It is recommended that the decoupling

capacitors used on both REFCAP and the supplies, be placed as

close as possible to their respective ball connections to ensure

high performance from the device. All analog and digital sup-

plies should be decoupled to AGND and DGND respectively,

with 0.1 µF ceramic capacitors in parallel with 10 µF tantalum

capacitors. The AFE’s digital section supply (DVDD) should be

connected to the digital supply that feeds the DSP’s VDD(Ext)

connections while the AFE’s digital ground DGND should be

returned to the digital ground plane.

Avoid running digital lines under the AFE section of the device

for they will couple noise onto the die. The analog ground plane

should be allowed to run under the AD73422’s AFE section to

avoid noise coupling (see Figure 35). The power supply lines to

the AD73422 should use as large a trace as possible to provide

low impedance paths and reduce the effects of glitches on the

power supply lines. Fast switching signals such as clocks should

be shielded with digital ground to avoid radiating noise to other

sections of the board, and clock signals should never be run near

OUTLINE DIMENSIONS

Dimensions shown in inches and (mm).

119-Ball Plastic Ball Grid Array (PBGA)

B-119

0.300 (7.62) BSC

0.559 (14.20)

BOTTOM

0.543 (13.80)

A1

7

6 5 4 3 2 1

VIEW

A

B

C

D

E

F

G

H

J

K

L

0.050

(1.27)

BSC

0.800

(20.32)

BSC

0.874 (22.20)

0.858 (21.80)

TOP VIEW

M

N

P

R

T

0.033

(0.84)

REF

U

0.050 (1.27)

BSC

0.126 (3.19)

REF

0.037 (0.95)

0.033 (0.85)

DETAIL A

0.028 (0.70)

0.020 (0.50)

0.089 (2.27)

0.073 (1.85)

0.022 (0.56)

REF

0.035 (0.90)

0.024 (0.60)

BALL DIAMETER

SEATING

PLANE

–36–

REV. 0


型号：	AD73422BB-40
厂家：	ADI
描述：	Dual Low Power CMOS Analog Front End with DSP Microcomputer 双路低功耗CMOS模拟前端与DSP单片机结束微控制器和处理器外围集成电路数字信号处理器时钟
文件：	总36页 (文件大小：395K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

AD73422BB-40 [ADI]

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