LTC2257-14_15_技术文档

LTC2258-14

LTC2257-14/LTC2256-14

14-Bit, 65/40/25Msps

Ultralow Power 1.8V ADCs

FeaTures

DescripTion

The LTC^®2258-14/LTC2257-14/LTC2256-14 are sam-

pling 14-bit A/D converters designed for digitizing high

frequency, wide dynamic range signals. They are perfect

for demanding communications applications with AC

performance that includes 74dB SNR and 88dB spurious

n

74dB SNR

n

88dB SFDR

Low Power: 81mW/49mW/35mW

Single 1.8V Supply

CMOS, DDR CMOS or DDR LVDS Outputs

Selectable Input Ranges: 1V to 2V

800MHz Full-Power Bandwidth S/H

Optional Data Output Randomizer

Optional Clock Duty Cycle Stabilizer

Shutdown and Nap Modes

Serial SPI Port for Configuration

Pin Compatible 14-Bit and 12-Bit Versions

40-Pin (6mm × 6mm) QFN Package

free dynamic range (SFDR). Ultralow jitter of 0.17ps

allows undersampling of IF frequencies with excellent

noise performance.

P-P

RMS

DCspecsinclude 1LSBINL(typical), 0.3LSBDNL(typi-

cal)andnomissingcodesovertemperature.Thetransition

noise is a low 1.13LSB

.

RMS

The digital outputs can be either full rate CMOS, double

data rate CMOS, or double data rate LVDS. A separate

output power supply allows the CMOS output swing to

range from 1.2V to 1.8V.

applicaTions

n

+

–

Communications

The ENC and ENC inputs may be driven differentially

or single ended with a sine wave, PECL, LVDS, TTL or

CMOS inputs. An optional clock duty cycle stabilizer al-

lows high performance at full speed for a wide range of

clock duty cycles.

n

Cellular Base Stations

n

Software Defined Radios

Portable Medical Imaging

Multi-Channel Data Acquisition

Nondestructive Testing

n

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Typical applicaTion

LTC2258-14 2-Tone FFT,

f_IN= 68MHz and 69MHz

1.8V

V

1.2V

0

–10

–20

–30

–40

–50

–60

–70

TO 1.8V

DD

OV

DD

D13

+

14-BIT

PIPELINED

ADC CORE

CMOS

OR

LVDS

•

CORRECTION

LOGIC

ANALOG

INPUT

OUTPUT

DRIVERS

INPUT

S/H

–

D0

–80

–90

OGND

–100

–110

–120

CLOCK/DUTY

CYCLE

CONTROL

0

20

10

FREQUENCY (MHz)

30

225814 TA01a

GND

65MHz

CLOCK

225814 TA01b

225814fc

1

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

absoluTe MaxiMuM raTings ^{(Notes 1, 2)}

Supply Voltages (V , OV )....................... –0.3V to 2V

Digital Output Voltage................ –0.3V to (OV + 0.3V)

DD

+

–

Analog Input Voltage (A , A

,

Operating Temperature Range:

IN

PAR/SER, SENSE) (Note 3).......... –0.3V to (V + 0.2V)

LTC2258C, LTC2257C, LTC2256C............ 0°C to 70°C

LTC2258I, LTC2257I, LTC2256I...........–40°C to 85°C

Storage Temperature Range .................. –65°C to 150°C

DD

+

–

Digital Input Voltage (ENC , ENC , CS,

SDI, SCK) (Note 4).................................... –0.3V to 3.9V

SDO (Note 4)............................................. –0.3V to 3.9V

pin conFiguraTions

DOUBLE DATA RATE CMOS OUTPUT MODE

TOP VIEW

FULL-RATE CMOS OUTPUT MODE

TOP VIEW

40 39 38 37 36 35 34 33 32 31

+

40 39 38 37 36 35 34 33 32 31

+

A

1

2

30

29

28

D9

IN

A

1

2

30

29

28

D8_9

IN

–

D8

IN

DNC

+

–

+

–

GND

REFH

3

CLKOUT

GND

REFH

3

CLKOUT

4

27 CLKOUT

4

27 CLKOUT

REFH

5

26 OV

DD

REFH

5

26 OV

DD

41

REFL

6

25

OGND

24 D7

23

REFL

6

25

OGND

REFL

7

REFL

7

24 D6_7

PAR/SER

8

D6

22 D5

21

PAR/SER

8

23

22

21

DNC

D4_5

DNC

V

DD

9

V

DD

9

V

10

D4

DD

V

10

DD

11 12 13 14 15 16 17 18 19 20

UJ PACKAGE

40-LEAD (6mm × 6mm) PLASTIC QFN

UJ PACKAGE

40-LEAD (6mm × 6mm) PLASTIC QFN

T

= 150°C, θ = 32°C/W

JA

JMAX

T

= 150°C, θ = 32°C/W

JMAX JA

EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB

DOUBLE DATA RATE LVDS OUTPUT MODE

TOP VIEW

40 39 38 37 36 35 34 33 32 31

+

–

+

–

A

1

2

30

29

28

D8_9

IN

+

–

GND

REFH

3

CLKOUT

4

27 CLKOUT

REFH

5

26 OV

DD

41

REFL

6

25

OGND

+

REFL

7

24 D6_7

–

+

–

PAR/SER

8

23

D6_7

22 D4_5

21

V

DD

9

V

DD

10

D4_5

11 12 13 14 15 16 17 18 19 20

UJ PACKAGE

40-LEAD (6mm × 6mm) PLASTIC QFN

T

= 150°C, θ = 32°C/W

JA

JMAX

EXPOSED PAD (PIN 41) IS GND, MUST BE SOLDERED TO PCB

225814fc

2

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

orDer inForMaTion

LEAD FREE FINISH

LTC2258CUJ-14#PBF

LTC2258IUJ-14#PBF

LTC2257CUJ-14#PBF

LTC2257IUJ-14#PBF

LTC2256CUJ-14#PBF

LTC2256IUJ-14#PBF

TAPE AND REEL

PART MARKING*

LTC2258UJ-14

LTC2257UJ-14

LTC2256UJ-14

PACKAGE DESCRIPTION

TEMPERATURE RANGE

0°C to 70°C

LTC2258CUJ-14#TRPBF

LTC2258IUJ-14#TRPBF

LTC2257CUJ-14#TRPBF

LTC2257IUJ-14#TRPBF

LTC2256CUJ-14#TRPBF

LTC2256IUJ-14#TRPBF

40-Lead (6mm × 6mm) Plastic QFN

–40°C to 85°C

0°C to 70°C

–40°C to 85°C

0°C to 70°C

–40°C to 85°C

Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.

Consult LTC Marketing for information on non-standard lead based finish parts.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/

converTer characTerisTics _{The l denotes the specifications which apply over the full operating}

temperature range, otherwise specifications are at T_A= 25°C. (Note 5)

LTC2258-14

TYP

LTC2257-14

TYP

LTC2256-14

MIN TYP MAX

PARAMETER

CONDITIONS

MIN

14

MAX

MIN

14

MAX

UNITS

Bits

l

Resolution (No Missing Codes)

Integral Linearity Error

Differential Linearity Error

Offset Error

14

–2.5

–0.8

–9

Differential Analog Input (Note 6)

Differential Analog Input

(Note 7)

–3

1

3

0.8

9

–2.5

–0.8

–9

1

2.5

0.8

9

1

2.5

0.8

9

LSB

mV

–0.8

–9

0.3

1.5

0.3

1.5

0.3

1.5

Gain Error

Internal Reference

External Reference

1.5

0.4

1.5

0.4

1.5

0.4

%FS

l

–1.5

1.5

–1.5

1.5

–1.5

1.5

Offset Drift

20

µV/°C

Full-Scale Drift

Internal Reference

External Reference

30

10

30

10

30

10

ppm/°C

Transition Noise

External Reference

1.13

LSB

RMS

225814fc

3

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

analog inpuT ^Thel denotes the specifications which apply over the full operating temperature range, otherwise

specifications are at T_A= 25°C. (Note 5)

SYMBOL PARAMETER

CONDITIONS

1.7V < V < 1.9V

MIN

TYP

MAX

UNITS

+

–

l

V

Analog Input Range (A – A

)

1 to 2

V

P-P

IN

DD

+

–

Analog Input Common Mode (A + A )/2 Differential Analog Input (Note 8)

V

CM

– 100mV

0.625

V

CM

V

CM

+ 100mV

1.300

V

IN(CM)

SENSE

INCM

IN

External Voltage Reference Applied to SENSE External Reference Mode

1.250

V

I

Analog Input Common Mode Current

Per Pin, 65Msps

Per Pin, 40Msps

Per Pin, 25Msps

81

50

31

µA

+

–

l

I

t

Analog Input Leakage Current

0 < A , A < V , No Encode

–1

–3

–6

1

3

6

µA

ns

IN1

IN

DD

PAR/SER Input Leakage Current

SENSE Input Leakage Current

0 < PAR/SER < V

IN2

DD

0.625 < SENSE < 1.3V

IN3

Sample-and-Hold Acquisition Delay Time

Sample-and-Hold Acquisition Delay Jitter

Analog Input Common Mode Rejection Ratio

Full-Power Bandwidth

0

AP

0.17

80

ps

RMS

JITTER

CMRR

BW-3B

dB

Figure 6 Test Circuit

800

MHz

DynaMic accuracy ^Thel denotes the specifications which apply over the full operating temperature range,

otherwise specifications are at T_A= 25°C. A_IN= –1dBFS. (Note 5)

LTC2258-14

TYP

LTC2257-14

TYP

LTC2256-14

SYMBOL PARAMETER

CONDITIONS

MIN

MAX

MIN

MAX

MIN

TYP MAX UNITS

SNR

Signal-to-Noise Ratio

5MHz Input

74

73.8

73.7

73

73.4

73.2

73.1

72.6

72.9

72.8

72.1

71.8

dB

l

30MHz Input

70MHz Input

140MHz Input

72.4

71.9

71.2

SFDR

Spurious Free Dynamic Range 5MHz Input

2nd or 3rd Harmonic

90

84

90

84

90

84

dB

30MHz Input

70MHz Input

140MHz Input

78

85

80

85

80

85

Spurious Free Dynamic Range 5MHz Input

4th Harmonic or Higher

90

84

dB

30MHz Input

70MHz Input

140MHz Input

S/(N+D) Signal-to-Noise Plus

Distortion Ratio

5MHz Input

73.8

73.7

73.6

72.5

73.2

73.1

73

72.8

72.7

72

dB

30MHz Input

70MHz Input

140MHz Input

71.5

70.7

72.3

71.2

inTernal reFerence characTerisTics ^Thel denotes the specifications which apply over the

full operating temperature range, otherwise specifications are at T_A= 25°C. (Note 5)

PARAMETER

CONDITIONS

= 0

MIN

TYP

0.5 • V

25

MAX

UNITS

V

CM

V

CM

V

CM

V

REF

V

REF

V

REF

V

REF

Output Voltage

I

0.5 • V – 25mV

0.5 • V + 25mV

OUT

DD

Output Temperature Drift

Output Resistance

Output Voltage

ppm/°C

Ω

–600µA < I

< 1mA

4

OUT

I

= 0

1.225

1.250

25

1.275

V

OUT

Output Temperature Drift

Output Resistance

Line Regulation

ppm/°C

Ω

–400µA < I

7

OUT

1.7V < V < 1.9V

0.6

mV/V

DD

225814fc

4

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

DigiTal inpuTs anD ouTpuTs ^Thel denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. (Note 5)

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

+

–

ENCODE INPUTS (ENC , ENC )

–

Differential Encode Mode (ENC Not Tied to GND)

l

V

Differential Input Voltage

(Note 8)

0.2

V

ID

Common Mode Input Voltage

Internally Set

Externally Set (Note 8)

1.2

V

ICM

l

1.1

0.2

1.6

3.6

+

–

V

IN

Input Voltage Range

Input Resistance

ENC , ENC to GND

(See Figure 10)

(Note 8)

V

kΩ

pF

R

10

IN

C

Input Capacitance

3.5

–

Single-Ended Encode Mode (ENC Tied to GND)

l

V

High Level Input Voltage

Low Level Input Voltage

Input Voltage Range

Input Resistance

V

= 1.8V

1.2

0

V

IH

IL

IN

DD

0.6

3.6

+

ENC to GND

(See Figure 11)

(Note 8)

V

R

30

kΩ

pF

IN

C

Input Capacitance

3.5

DIGITAL INPUTS (CS, SDI, SCK)

l

V

High Level Input Voltage

Low Level Input Voltage

Input Current

V

= 1.8V

1.3

V

IH

IL

DD

IN

= 1.8V

0.6

10

I

IN

= 0V to 3.6V

–10

µA

pF

C

IN

Input Capacitance

(Note 8)

3

200

4

SDO OUTPUT (Open-Drain Output. Requires 2k Pull-Up Resistor if SDO is Used)

R

Logic Low Output Resistance to GND

Logic High Output Leakage Current

Output Capacitance

V

= 1.8V, SDO = 0V

DD

Ω

µA

pF

OL

l

I

SDO = 0V to 3.6V

(Note 8)

–10

10

OH

C

OUT

DIGITAL DATA OUTPUTS (CMOS MODES: FULL DATA RATE AND DOUBLE DATA RATE)

OV = 1.8V

DD

l

V

OH

V

OL

High Level Output Voltage

Low Level Output Voltage

I = –500µA

1.750

1.790

0.010

V

O

I = 500µA

O

0.050

OV = 1.5V

DD

V

High Level Output Voltage

Low Level Output Voltage

I = –500µA

1.488

0.010

V

OH

OL

O

I = 500µA

O

OV = 1.2V

DD

V

High Level Output Voltage

Low Level Output Voltage

I = –500µA

1.185

0.010

V

OH

OL

O

I = 500µA

O

DIGITAL DATA OUTPUTS (LVDS MODE)

l

V

Differential Output Voltage

100Ω Differential Load, 3.5mA Mode

100Ω Differential Load, 1.75mA Mode

247

350

175

454

mV

OD

V

Common Mode Output Voltage

On-Chip Termination Resistance

100Ω Differential Load, 3.5mA Mode

100Ω Differential Load, 1.75mA Mode

1.125

1.250

1.375

V

OS

R

Termination Enabled, OV = 1.8V

100

Ω

TERM

DD

225814fc

5

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

power requireMenTs ^Thel denotes the specifications which apply over the full operating temperature

range, otherwise specifications are at T_A= 25°C. (Note 9)

LTC2258-14

TYP

LTC2257-14

TYP

LTC2256-14

MIN TYP MAX UNITS

SYMBOL PARAMETER

CONDITIONS

MIN

MAX

MIN

MAX

CMOS Output Modes: Full Data Rate and Double Data Rate

l

V

Analog Supply Voltage

Output Supply Voltage

Analog Supply Current

(Note 10)

1.7

1.1

1.8

1.9

1.7

1.1

1.8

1.9

30

1.7

1.1

1.8

1.9

22

V

DD

OV

DD

I

DC Input

Sine Wave Input

44.7

45.3

49.5

27

27.9

19.5

19.9

mA

VDD

I

Digital Supply Current

Power Dissipation

Sine Wave Input, OV =1.2V

2.6

1.6

1.1

mA

OVDD

DD

l

P

DC Input

80.5

84.7

90

48.6

52.1

54

35.1

37.1

40

mW

DISS

Sine Wave Input, OV =1.2V

DD

LVDS Output Mode

l

V

Analog Supply Voltage

Output Supply Voltage

Analog Supply Current

Digital Supply Current

(Note 10)

1.7

1.8

1.9

54

1.7

1.8

1.9

35

1.7

1.8

1.9

26

V

DD

OV

(Note 10)

DD

I

Sine Wave Input

48.9

31.4

23.5

mA

VDD

OVDD

l

Sine Input, 1.75mA Mode

Sine Input, 3.5mA Mode

20.7

40.5

23

44

20.7

40.5

23

44

20.7

40.5

23

44

mA

(0V = 1.8V)

DD

l

P

DISS

Power Dissipation

Sine Input, 1.75mA Mode

Sine Input, 3.5mA Mode

125.3 139

160.9 177

93.8

105

79.6

89

mW

129.4 143

115.2 126

All Output Modes

P

Sleep Mode Power

Nap Mode Power

0.5

9

0.5

9

0.5

9

mW

SLEEP

NAP

Power Increase with Differential Encode Mode Enabled

(No increase for Nap or Sleep Modes)

10

DIFFCLK

TiMing characTerisTics ^Thel denotes the specifications which apply over the full operating temperature

range, otherwise specifications are at T_A= 25°C. (Note 5)

LTC2258-14

TYP

LTC2257-14

TYP

LTC2256-14

MIN TYP MAX UNITS

SYMBOL PARAMETER

CONDITIONS

MIN

MAX

MIN

MAX

l

f

S

t

L

Sampling Frequency

(Note 10)

1

65

1

40

1

25

MHz

l

ENC Low Time (Note 8) Duty Cycle Stabilizer Off

Duty Cycle Stabilizer On

7.3

2.0

7.69

500 11.88 12.5

500 2.00 12.5

500

19

2.00

20

500

ns

l

t

H

ENC High Time (Note 8) Duty Cycle Stabilizer Off

Duty Cycle Stabilizer On

7.3

2.0

7.69

500 11.88 12.5

500

19

2.00

20

500

ns

500

2.00

12.5

t

AP

Sample-and-Hold

Acquisition Delay Time

0

ns

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Digital Data Outputs (CMOS Modes: Full Data Rate and Double Data Rate)

l

t

ENC to Data Delay

ENC to CLKOUT Delay

DATA to CLKOUT Skew

Pipeline Latency

C = 5pF (Note 8)

1.1

1

1.7

1.4

0.3

3.1

2.6

0.6

ns

D

L

C = 5pF (Note 8)

L

C

t – t (Note 8)

0

SKEW

D

C

Full Data Rate Mode

Double Data Rate Mode

5.0

5.5

Cycles

225814fc

6

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

TiMing characTerisTics ^Thel denotes the specifications which apply over the full operating temperature

range, otherwise specifications are at T_A= 25°C. (Note 5)

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Digital Data Outputs (LVDS Mode)

l

t

ENC to Data Delay

ENC to CLKOUT Delay

DATA to CLKOUT Skew

Pipeline Latency

C = 5pF (Note 8)

1.1

1

1.8

1.5

0.3

5.5

3.2

2.7

0.6

ns

D

L

C = 5pF (Note 8)

L

C

t – t (Note 8)

0

ns

SKEW

D

C

Cycles

SPI Port Timing (Note 8)

l

t

SCK Period

Write Mode

40

ns

SCK

Readback Mode, C

= 20pF, R

= 2k

250

SDO

PULLUP

l

t

CS to SCK Setup Time

SCK to CS Setup Time

SDI Setup Time

5

ns

S

H

DS

DH

DO

SDI Hold Time

SCK Falling to SDO Valid

Readback Mode, C

125

PULLUP

+

–

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

termination disabled, differential ENC /ENC = 2V sine wave, input

P-P

range = 2V with differential drive, unless otherwise noted.

P-P

Note 6: Integral nonlinearity is defined as the deviation of a code from a

best fit straight line to the transfer curve. The deviation is measured from

the center of the quantization band.

Note 2: All voltage values are with respect to GND with GND and OGND

shorted (unless otherwise noted).

Note 3: When these pin voltages are taken below GND or above V , they

will be clamped by internal diodes. This product can handle input currents

Note 7: Offset error is the offset voltage measured from –0.5 LSB when

the output code flickers between 00 0000 0000 0000 and 11 1111 1111

1111 in 2’s complement output mode.

DD

of greater than 100mA below GND or above V without latchup.

DD

Note 8: Guaranteed by design, not subject to test.

Note 4: When these pin voltages are taken below GND they will be

clamped by internal diodes. When these pin voltages are taken above V

they will not be clamped by internal diodes. This product can handle input

currents of greater than 100mA below GND without latchup.

Note 9: V = 1.8V, f

25MHz (LTC2256), ENC = single-ended 1.8V square wave, ENC = 0V,

= 65MHz (LTC2258), 40MHz (LTC2257), or

DD

SAMPLE

+

–

DD

input range = 2V with differential drive, 5pF load on each digital output

P-P

unless otherwise noted.

Note 5: V = OV = 1.8V, f = 65MHz (LTC2258),

40MHz (LTC2257), or 25MHz (LTC2256), LVDS outputs with internal

DD

SAMPLE

Note 10: Recommended operating conditions.

225814fc

7

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

TiMing DiagraMs

Full-Rate CMOS Output Mode Timing

All Outputs Are Single-Ended and Have CMOS Levels

t

AP

N + 4

N + 2

ANALOG

INPUT

N

N + 3

t

H

N + 1

t

L

–

ENC

+

ENC

t

D

N – 5

N – 4

N – 3

N – 2

N – 1

D0-D13, OF

t

C

+

CLKOUT

–

CLKOUT

225814 TD01

Double Data Rate CMOS Output Mode Timing

All Outputs Are Single-Ended and Have CMOS Levels

t

AP

N + 4

N + 2

ANALOG

INPUT

N

N + 3

t

H

N + 1

t

L

–

ENC

+

ENC

t

D

D0_1

D0

D1

D0

D1

D0

N-3

D1

D0

D1

N-2

N-5

N-4

N-3

N-2

•

D12_13

OF

D12

D13

D12

OF

D13

D12

D13

D12

D13

N-2

N-5

N-4

N-3

N-2

OF

N-2

N-5

N-4

N-3

t

C

+

CLKOUT

–

CLKOUT

225814 TD02

225814fc

8

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

TiMing DiagraMs

Double Data Rate LVDS Output Mode Timing

All Outputs Are Differential and Have LVDS Levels

t

AP

N + 4

N + 2

ANALOG

INPUT

N

N + 3

t

H

N + 1

t

L

–

ENC

+

ENC

t

D

+

D0_1

D0

D1

D0

N-4

D1

D0

D1

D0

D1

N-2

N-5

N-4

N-3

N-2

–

D0_1

•

+

D12_13

D12

D13

D12

D13

D12

D13

D12

D13

N-2

N-5

N-4

N-3

N-2

–

D12_13

+

OF

N-5

OF

N-4

OF

N-3

OF

N-3

–

OF

t

C

t

C

+

CLKOUT

–

CLKOUT

225814 TD03

SPI Port Timing (Readback Mode)

t

S

t

DS

t

DH

t

H

SCK

CS

SCK

t

DO

SDI

A6

A5

A4

A3

A2

A1

A0

XX

D6

XX

D5

XX

D4

XX

D3

XX

D2

XX

D1

XX

R/W

SDO

D7

D0

HIGH IMPEDANCE

SPI Port Timing (Write Mode)

CS

SCK

SDI

A6

A5

A4

A3

A2

A1

A0

D7

D6

D5

D4

D3

D2

D1

D0

R/W

SDO

225814 TD04

225814fc

9

HIGH IMPEDANCE

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical perForMance characTerisTics

LTC2258-14: Integral

Nonlinearity (INL)

LTC2258-14: Differential

Nonlinearity (DNL)

LTC2258-14: 8k Point FFT,

f_IN= 5MHz, –1dBFS, 65Msps

1.0

0.8

0.6

0

–10

–20

–30

–40

–50

–60

–70

2.0

1.5

1.0

0.4

0.2

0

0.5

0

–0.2

–0.4

–0.6

–0.8

–1.0

–0.5

–1.0

–1.5

–2.0

–80

–90

–100

–110

–120

0

8192

12288

16384

4096

0

20

10

FREQUENCY (MHz)

30

0

8192

12288

16384

4096

OUTPUT CODE

225814 G02

225814 G03

225814 G01

LTC2258-14: 8k Point FFT,

f_IN= 30MHz, –1dBFS, 65Msps

LTC2258-14: 8k Point FFT,

f_IN= 70MHz, –1dBFS, 65Msps

LTC2258-14: 8k Point FFT,

f_IN= 140MHz, –1dBFS, 65Msps

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–80

–90

–80

–90

–100

–110

–120

–100

–110

–120

–100

–110

–120

0

20

10

FREQUENCY (MHz)

30

0

10

20

30

0

20

10

FREQUENCY (MHz)

30

FREQUENCY (MHz)

225814 G04

225814 G05

225814 G06

LTC2258-14: SNR vs Input

Frequency, –1dB, 2V Range,

65Msps

LTC2258-14: 8k Point 2-Tone FFT,

f_IN= 68MHz, 69MHz, –1dBFS,

65Msps

LTC2258-14: Shorted Input

Histogram

0

–10

–20

–30

–40

–50

–60

–70

6000

5000

4000

3000

74

73

72

71

70

69

68

67

66

–80

–90

–100

–110

–120

2000

1000

0

20

10

FREQUENCY (MHz)

30

8197

8201

8203

8205

0

100 150 200 250 300 350

INPUT FREQUENCY (MHz)

8199

50

OUTPUT CODE

225814 G07

225814 G08

225814 G09

225814fc

10

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical perForMance characTerisTics

LTC2258-14: SFDR vs Input

Frequency, –1dB, 2V Range,

65Msps

LTC2258-14: SFDR vs Input Level,

f_IN= 70MHz, 2V Range, 65Msps

LTC2258-14: I_VDDvs Sample Rate,

5MHz Sine Wave Input, –1dB

50

45

40

95

90

85

80

75

70

65

110

100

90

dBFS

LVDS OUTPUTS

CMOS OUTPUTS

80

70

60

dBc

50

40

30

20

10

0

35

30

0

20

40

60

0

100 150 200 250 300 350

INPUT FREQUENCY (MHz)

50

–80

–60 –50 –40 –30 –20 –10

INPUT LEVEL (dBFS)

0

–70

SAMPLE RATE (Msps)

225814 G13

225814 G10

225814 G12

LTC2258-14: I_OVDDvs Sample

Rate, 5MHz Sine Wave Input,

LTC2258-14: SNR vs SENSE,

f_IN= 5MHz, –1dB

LTC2257-14: Integral Nonlinearity

(INL)

–1dB, 5pF on Each Data Output

45

40

35

30

25

20

15

2.0

1.5

75

74

73

72

71

70

3.5mA LVDS

1.0

0.5

1.75mA LVDS

0

–0.5

–1.0

–1.5

–2.0

69

68

67

10

5

1.2V CMOS

1.8V CMOS

0

20

40

60

0.6 0.7 0.8 0.9

1

1.1 1.2 1.3

0

8192

12288

16384

4096

SAMPLE RATE (Msps)

SENSE PIN (V)

OUTPUT CODE

225814 G14

225814 G15

225814 G21

LTC2257-14: 8k Point FFT,

f_IN= 5MHz, –1dBFS, 40Msps

LTC2257-14: 8k Point FFT,

f_IN= 29MHz, –1dBFS, 40Msps

LTC2257-14: Differential

Nonlinearity (DNL)

1.0

0.8

0.6

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

0.4

0.2

0

–0.2

–0.4

–0.6

–0.8

–1.0

–80

–90

–100

–110

–120

–80

–90

–100

–110

–120

0

8192

12288

16384

0

20

4096

10

0

20

10

OUTPUT CODE

FREQUENCY (MHz)

225814 G22

225814 G23

225814 G24

225814fc

11

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical perForMance characTerisTics

LTC2257-14: 8k Point 2-Tone FFT,

f_IN= 68MHz, 69MHz, –1dBFS,

40Msps

LTC2257-14: 8k Point FFT,

f_IN= 139MHz, –1dBFS, 40Msps

f_IN= 69MHz, –1dBFS, 40Msps

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–80

–90

–80

–90

–100

–110

–120

–100

–110

–120

–100

–110

–120

0

20

0

20

10

0

20

10

FREQUENCY (MHz)

225814 G27

225814 G26

225814 G25

LTC2257-14: SNR vs Input

Frequency, –1dB, 2V Range,

40Msps

LTC2257-14: SFDR vs Input

Frequency, –1dB, 2V Range,

40Msps

LTC2257-14: Shorted Input

Histogram

74

73

72

71

70

6000

5000

4000

3000

95

90

85

80

75

70

65

69

68

67

66

2000

1000

0

100 150 200 250 300 350

INPUT FREQUENCY (MHz)

50

8198

8202

8204

8206

8200

0

100 150 200 250 300 350

50

OUTPUT CODE

INPUT FREQUENCY (MHz)

225814 G30

225814 G29

225814 G28

LTC2257-14: I_OVDDvs Sample

Rate, 5MHz Sine Wave Input,

–1dB, 5pF on Each Data Output

LTC2257-14: SFDR vs Input Level,

LTC2257-14: I_VDDvs Sample Rate,

5MHz Sine Wave Input, –1dB

f

_IN= 70MHz, 2V Range, 40Msps

45

40

35

30

25

20

15

110

100

90

35

30

25

20

15

3.5mA LVDS

dBFS

LVDS OUTPUTS

80

70

60

1.75mA LVDS

dBc

50

40

30

20

10

0

CMOS OUTPUTS

1.2V CMOS

1.8V CMOS

10

5

0

20

40

–80

–60 –50 –40 –30 –20 –10

INPUT LEVEL (dBFS)

0

20

40

–70

SAMPLE RATE (Msps)

225814 G34

225814 G32

225814 G33

225814fc

12

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical perForMance characTerisTics

LTC2257-14: SNR vs SENSE,

f_IN= 5MHz, –1dB

LTC2256-14: Integral Nonlinearity

(INL)

LTC2256-14: Differential

Nonlinearity (DNL)

1.0

0.8

0.6

2.0

1.5

74

73

72

71

70

69

1.0

0.4

0.2

0

0.5

0

–0.2

–0.4

–0.6

–0.8

–1.0

–0.5

–1.0

–1.5

–2.0

68

67

66

0

8192

12288

16384

0

8192

12288

16384

4096

0.6 0.7 0.8 0.9

1

1.1 1.2 1.3

4096

OUTPUT CODE

SENSE PIN (V)

225814 G42

225814 G41

225814 G35

LTC2256-14: 8k Point FFT,

f_IN= 5MHz, –1dBFS, 25Msps

LTC2256-14: 8k Point FFT,

f_IN= 30MHz, –1dBFS, 25Msps

LTC2256-14: 8k Point FFT,

f_IN= 70MHz, –1dBFS, 25Msps

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–80

–90

–80

–90

–100

–110

–120

–100

–110

–120

–100

–110

–120

0

10

0

10

5

0

10

5

FREQUENCY (MHz)

225814 G44

225814 G43

225814 G45

LTC2256-14: 8k Point 2-Tone FFT,

f_IN= 68MHz, 69MHz, –1dBFS,

25Msps

LTC2256-14: Shorted Input

Histogram

LTC2256-14: 8k Point FFT,

_IN= 140MHz, –1dBFS, 25Msps

f

0

–10

–20

–30

–40

–50

–60

–70

0

–10

–20

–30

–40

–50

–60

–70

6000

5000

4000

3000

–80

–90

–100

–110

–120

–80

–90

–100

–110

–120

2000

1000

0

10

5

0

10

5

8198

8202

8204

8206

8200

FREQUENCY (MHz)

OUTPUT CODE

225814 G46

225814 G47

225814 G48

225814fc

13

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical perForMance characTerisTics

LTC2256-14: SNR vs Input

Frequency, –1dB, 2V Range,

25Msps

LTC2256-14: SFDR vs Input

Frequency, –1dB, 2V Range,

25Msps

LTC2256-14: SFDR vs Input Level,

f_IN= 70MHz, 2V Range, 25Msps

95

90

85

80

75

70

65

110

100

90

74

73

72

71

70

dBFS

80

70

dBc

60

50

40

30

20

10

0

69

68

67

66

0

100 150 200 250 300 350

INPUT FREQUENCY (MHz)

50

–80

–60 –50 –40 –30 –20 –10

INPUT LEVEL (dBFS)

0

–70

0

100 150 200 250 300 350

INPUT FREQUENCY (MHz)

50

225814 G50

225814 G52

225814 G49

LTC2256-14: I_OVDDvs Sample Rate,

5MHz Sine Wave Input, –1dB, 5pF

on Each Data Output

LTC2256-14: SNR vs SENSE,

f_IN= 5MHz, –1dB

LTC2256-14: I_VDDvs Sample Rate,

5MHz Sine Wave Input, –1dB

25

45

40

35

30

25

20

15

74

73

72

71

70

69

3.5mA LVDS

LVDS OUTPUTS

1.75mA LVDS

20

15

CMOS OUTPUTS

68

67

66

10

5

1.2V CMOS

20

1.8V CMOS

10

0

10

20

0

0.6 0.7 0.8 0.9

1

1.1 1.2 1.3

SAMPLE RATE (Msps)

SENSE PIN (V)

225814 G54

225814 G53

225814 G55

225814fc

14

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

pin FuncTions

PINS THAT ARE THE SAME FOR ALL DIGITAL OUTPUT

MODES

parallel programming mode (PAR/SER = V ), SCK

DD

controls the digital output mode. When SCK is low,

the full-rate CMOS output mode is enabled. When SCK

is high, the double data rate LVDS output mode (with

3.5mA output current) is enabled. SCK can be driven

with 1.8V to 3.3V logic.

+

A

IN

A

IN

(Pin 1): Positive Differential Analog Input.

(Pin 2): Negative Differential Analog Input.

–

GND (Pin 3): ADC Power Ground.

SDI (Pin 15): In serial programming mode, (PAR/SER =

0V), SDI is the serial interface data input. Data on SDI is

clocked into the mode control registers on the rising edge

of SCK. In the parallel programming mode (PAR/SER =

REFH (Pins 4, 5): ADC High Reference. Bypass to Pins

6, 7 with a 2.2µF ceramic capacitor and to ground with a

0.1µF ceramic capacitor.

REFL (Pins 6, 7): ADC Low Reference. Bypass to Pins

4, 5 with a 2.2µF ceramic capacitor and to ground with a

0.1µF ceramic capacitor.

V ), SDI can be used to power down the part. When SDI

DD

is low, the part operates normally. When SDI is high, the

part enters sleep mode. SDI can be driven with 1.8V to

3.3V logic.

PAR/SER(Pin8):ProgrammingModeSelectionPin. Con-

nect to ground to enable the serial programming mode.

CS, SCK, SDI, SDO become a serial interface that control

SDO (Pin 16): In serial programming mode, (PAR/SER

= 0V), SDO is the optional serial interface data output.

Data on SDO is read back from the mode control registers

and can be latched on the falling edge of SCK. SDO is an

open-drain NMOS output that requires an external 2k

pull-up resistor to 1.8V-3.3V. If read back from the mode

control registers is not needed, the pull-up resistor is not

necessaryandSDOcanbeleftunconnected.Intheparallel

the A/D operating modes. Connect to V to enable the

DD

parallel programming mode where CS, SCK, SDI become

parallel logic inputs that control a reduced set of the A/D

operating modes. PAR/SER should be connected directly

to ground or the V of the part and not be driven by a

DD

logic signal.

programming mode (PAR/SER = V ), SDO is not used

DD

V

(Pins 9, 10, 40): 1.8V Analog Power Supply. Bypass

DD

and should not be connected.

to ground with 0.1µF ceramic capacitors. Pins 9 and 10

can share a bypass capacitor.

OGND (Pin 25): Output Driver Ground.

+

ENC (Pin 11): Encode Input. Conversion starts on the

OV (Pin 26): Output Driver Supply. Bypass to ground

DD

rising edge.

with a 0.1µF ceramic capacitor.

–

ENC (Pin 12): Encode Complement Input. Conversion

V

(Pin 37): Common Mode Bias Output, Nominally

CM

starts on the falling edge.

Equal to V /2. V should be used to bias the common

DD

CM

mode of the analog inputs. Bypass to ground with a 0.1µF

ceramic capacitor.

CS (Pin 13): In serial programming mode, (PAR/SER =

0V), CS is the serial interface chip select input. When

CS is low, SCK is enabled for shifting data on SDI into

the mode control registers. In the parallel programming

V

(Pin38):ReferenceVoltageOutput,Nominally1.25V.

REF

Bypass to ground with a 1µF ceramic capacitor.

mode (PAR/SER = V ), CS controls the clock duty cycle

DD

SENSE(Pin39):ReferenceProgrammingPin.Connecting

stabilizer. WhenCS islow, theclockduty cyclestabilizeris

turned off. When CS is high, the clock duty cycle stabilizer

is turned on. CS can be driven with 1.8V to 3.3V logic.

SENSEtoV selectstheinternalreferenceanda 1Vinput

DD

range. Connecting SENSE to ground selects the internal

reference and a 0.5V input range. An external reference

between 0.625V and 1.3V applied to SENSE selects an

SCK (Pin 14): In serial programming mode, (PAR/SER

= 0V), SCK is the serial interface clock input. In the

input range of ±0.8 • V

.

SENSE

225814fc

15

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

pin FuncTions

FULL-RATE CMOS OUTPUT MODE

DOUBLE DATA RATE LVDS OUTPUT MODE

All Pins Below Have CMOS Output Levels (OGND to

All Pins Below Have LVDS Output Levels. The Output

Current Level is Programmable. There is an Optional

Internal 100Ω Termination Resistor Between the Pins

of Each LVDS Output Pair.

OV )

DD

D0 to D13 (Pins 17-24, 29-34): Digital Outputs. D13 is

the MSB.

–

+

–

+

D0_1 /D0_1 to D12_13 /D12_13 (Pins 17/18, 19/20,

21/22, 23/24, 29/30, 31/32, 33/34): Double Data Rate

Digital Outputs. Two data bits are multiplexed onto each

differential output pair. The even data bits (D0, D2, D4,

–

+

CLKOUT (Pin 27): Inverted version of CLKOUT .

+

CLKOUT (Pin 28): Data Output Clock. The digital outputs

normally transition at the same time as the falling edge

+

of CLKOUT . The phase of CLKOUT can also be delayed

relative to the digital outputs by programming the mode

control registers.

D6, D8, D10, D12) appear when CLKOUT is low. The odd

data bits (D1, D3, D5, D7, D9, D11, D13) appear when

+

CLKOUT is high.

–

+

DNC (Pin 35): Do not connect this pin.

CLKOUT /CLKOUT (Pins 27/28): Data Output Clock.

The digital outputs normally transition at the same time

OF (Pin 36): Over/Under Flow Digital Output. OF is high

when an overflow or underflow has occurred.

+

as the falling and rising edges of CLKOUT . The phase of

+

CLKOUT canalsobedelayedrelativetothedigitaloutputs

by programming the mode control registers.

DOUBLE DATA RATE CMOS OUTPUT MODE

–

+

OF /OF (Pins 35/36): Over/Under Flow Digital Output.

OF is high when an overflow or underflow has occurred.

+

All Pins Below Have CMOS Output Levels (OGND to

OV )

DD

D0_1 to D12_13 (Pins 18, 20, 22, 24, 30, 32, 34): Double

Data Rate Digital Outputs. Two data bits are multiplexed onto

eachoutputpin. Theevendatabits(D0, D2, D4, D6, D8, D10,

+

D12) appear when CLKOUT is low. The odd data bits (D1,

+

D3, D5, D7, D9, D11, D13) appear when CLKOUT is high.

–

+

CLKOUT (Pin 27): Inverted version of CLKOUT .

+

CLKOUT (Pin 28): Data Output Clock. The digital outputs

normally transition at the same time as the falling and ris-

+

ing edges of CLKOUT . The phase of CLKOUT can also

be delayed relative to the digital outputs by programming

the mode control registers.

DNC (Pins 17, 19, 21, 23, 29, 31, 33, 35): Do not con-

nect these pins.

OF (Pin 36): Over/Under Flow Digital Output. OF is high

when an overflow or underflow has occurred.

225814fc

16

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

FuncTional block DiagraM

+

A

IN

V

DD

INPUT

S/H

FIRST PIPELINED

ADC STAGE

SECOND PIPELINED

ADC STAGE

THIRD PIPELINED

ADC STAGE

FOURTH PIPELINED

ADC STAGE

FIFTH PIPELINED

ADC STAGE

–

GND

V

CM

V

/2

DD

0.1µF

V

REF

1.25V

REFERENCE

SHIFT REGISTER

AND CORRECTION

1µF

RANGE

SELECT

REFH

REFL INTERNAL CLOCK SIGNALS

REF

BUF

OV

OF

DD

SENSE

D13

•

DIFF

REF

AMP

CLOCK/DUTY

CYCLE

CONTROL

MODE

OUTPUT

DRIVERS

CONTROL

REGISTERS

D0

+

–

CLKOUT

225814 F01

REFH

REFL

OGND

0.1µF

+

–

ENC

PAR/SER CS SCK SDI SDO

2.2µF

0.1µF

Figure 1. Functional Block Diagram

225814fc

17

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

applicaTions inForMaTion

CONVERTER OPERATION

ANALOG INPUT

TheLTC2258-14/LTC2257-14/LTC2256-14arelowpower

14-bit 65Msps/40Msps/25Msps A/D converters that are

poweredbyasingle1.8Vsupply.Theanaloginputsshould

be driven differentially. The encode input can be driven

differentially, or single ended for lower power consump-

tion. The digital outputs can be CMOS, double data rate

CMOS (to halve the number of output lines), or double

data rate LVDS (to reduce digital noise in the system.)

Many additional features can be chosen by programming

the mode control registers through a serial SPI port. See

the Serial Programming Mode section.

The analog input is a differential CMOS sample-and-hold

circuit(Figure2).Theinputsshouldbedrivendifferentially

around a common mode voltage set by the V output

CM

pin, which is nominally V /2. For the 2V input range,

DD

the inputs should swing from V – 0.5V to V + 0.5V.

CM

Thereshouldbe180°phasedifferencebetweentheinputs.

LTC2258-14

V

DD

C

SAMPLE

3.5pF

R

ON

10Ω

10Ω

25Ω

+

–

A

IN

C

PARASITIC

1.8pF

V

DD

SAMPLE

3.5pF

R

25Ω

ON

IN

C

PARASITIC

1.8pF

V

DD

1.2V

10k

+

–

ENC

10k

1.2V

225814 F02

Figure 2. Equivalent Input Circuit

225814fc

18

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INPUT DRIVE CIRCUITS

Transformer Coupled Circuits

Figure 3 shows the analog input being driven by an RF

transformer with a center-tapped secondary. The center

Input filtering

If possible, there should be an RC lowpass filter right at

the analog inputs. This lowpass filter isolates the drive

circuitry from the A/D sample-and-hold switching, and

alsolimitswidebandnoisefromthedrivecircuitry.Figure 3

showsanexampleofaninputRCfilter.TheRCcomponent

values should be chosen based on the application’s input

frequency.

tap is biased with V , setting the A/D input at its optimal

CM

DC level. At higher input frequencies a transmission line

balun transformer (Figures 4 to 6) has better balance,

resulting in lower A/D distortion.

50Ω

V

CM

50Ω

V

CM

0.1µF

+

A

ANALOG

INPUT

IN

T2

0.1µF

T1

1:1

+

LTC2258-14

25Ω

T1

A

IN

ANALOG

INPUT

0.1µF

25Ω

LTC2258-14

1.8pF

0.1µF

25Ω

–

A

12pF

IN

–

25Ω

A

IN

225814 F05

T1: MA/COM MABA-007159-000000

T2: COILCRAFT WBC1-1LB

RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE

T1: MA/COM MABAES0060

RESISTORS, CAPACITORS

ARE 0402 PACKAGE SIZE

225814 F03

Figure 3. Analog Input Circuit Using a Transformer.

Recommended for Input Frequencies from 5MHz to 70MHz

Figure 5. Recommended Front-End Circuit for Input

Frequencies from 170MHz to 270MHz

50Ω

V

CM

0.1µF

+

2.7nH

0.1µF

+

–

A

ANALOG

INPUT

IN

T2

ANALOG

INPUT

LTC2258-14

T1

0.1µF

25Ω

T1

4.7pF

–

2.7nH

A

IN

T1: MA/COM ETC1-1-13

225814 F04

225814 F06

RESISTORS, CAPACITORS

ARE 0402 PACKAGE SIZE

T1: MA/COM MABA-007159-000000

T2: MA/COM MABAES0060

RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE

Figure 4. Recommended Front-End Circuit for Input

Frequencies from 70MHz to 170MHz

Figure 6. Recommended Front-End Circuit for Input

Frequencies Above 270MHz

225814fc

19

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Amplifier Circuits

LTC2258-14

5Ω

V

REF

Figure 7 shows the analog input being driven by a high

speed differential amplifier. The output of the amplifier is

AC coupled to the A/D so the amplifier’s output common

mode voltage can be optimally set to minimize distortion.

1.25V BANDGAP

REFERENCE

1.25V

1µF

0.625V

RANGE

DETECT

AND

At very high frequencies an RF gain block will often have

lower distortion than a differential amplifier. If the gain

blockissingle-ended,thenatransformercircuit(Figures 4

to 6) should convert the signal to differential before driv-

ing the A/D.

CONTROL

TIE TO V FOR 2V RANGE;

DD

TIE TO GND FOR 1V RANGE;

SENSE

RANGE = 1.6 • V

FOR

SENSE

BUFFER

0.65V < V

SENSE

< 1.300V

INTERNAL ADC

HIGH REFERENCE

0.1µF

REFH

0.1µF

Reference

The LTC2258-14/2257-14/2256-14 has an internal 1.25V

voltage reference. For a 2V input range using the internal

reference, connect SENSE to V . For a 1V input range

2.2µF

0.1µF

0.8x

DIFF AMP

DD

REFL

using the internal reference, connect SENSE to ground.

For a 2V input range with an external reference, apply a

1.25V reference voltage to SENSE (Figure 9.)

INTERNAL ADC

LOW REFERENCE

225814 F08

The input range can be adjusted by applying a voltage to

SENSE that is between 0.625V and 1.30V. The input range

Figure 8. Reference Circuit

will then be 1.6 • V

.

SENSE

The V , REFH and REFL pins should be bypassed as

REF

V

REF

shown in Figure 8. The 0.1µF capacitor between REFH

and REFL should be as close to the pins as possible (not

on the back side of the circuit board).

1µF

LTC2258-14

1.25V

EXTERNAL

REFERENCE

SENSE

1µF

225814 F09

V

CM

HIGH SPEED

DIFFERENTIAL

AMPLIFIER

0.1µF

Figure 9. Using an External 1.25V Reference

200Ω 200Ω

25Ω

0.1µF

+

–

A

IN

LTC2258-14

ANALOG

INPUT

+

12pF

–

25Ω

A

IN

12pF

225814 F07

Figure 7. Front-End Circuit Using a High Speed

Differential Amplifier

225814fc

20

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Encode Input

Thesingle-endedencodemodeshouldbeusedwithCMOS

–

encode inputs. To select this mode, ENC is connected

The signal quality of the encode inputs strongly affects

the A/D noise performance. The encode inputs should

be treated as analog signals—do not route them next to

digital traces on the circuit board. There are two modes

of operation for the encode inputs: the differential encode

mode (Figure 10) and the single-ended encode mode

(Figure 11).

+

to ground and ENC is driven with a square wave encode

+

input. ENC can be taken above V (up to 3.6V) so 1.8V

DD

+

to3.3VCMOSlogiclevelscanbeused.TheENC threshold

is0.9V. ForgoodjitterperformanceENC shouldhavefast

+

rise and fall times.

Clock Duty Cycle Stabilizer

The differential encode mode is recommended for sinu-

soidal, PECL or LVDS encode inputs (Figures 12, 13). The

encode inputs are internally biased to 1.2V through 10k

equivalent resistance. The encode inputs can be taken

For good performance the encode signal should have a

50%( 5%) duty cycle. If the optional clock duty cycle

stabilizer circuit is enabled, the encode duty cycle can

vary from 30% to 70% and the duty cycle stabilizer will

maintain a constant 50% internal duty cycle. If the encode

signal changes frequency or is turned off, the duty cycle

stabilizer circuit requires one hundred clock cycles to lock

onto the input clock. The duty cycle stabilizer is enabled

above V (up to 3.6V), and the common mode range

DD

is from 1.1V to 1.6V. In the differential encode mode,

–

ENC should stay at least 200mV above ground to avoid

falselytriggeringthesingle-endedencodemode.Forgood

+

–

jitter performance ENC and ENC should have fast rise

and fall times.

LTC2258-14

0.1µF

V

DD

+

25Ω

ENC

T1

1:4

DIFFERENTIAL

COMPARATOR

100Ω

V

DD

D1

LTC2258-14

–

ENC

15k

30k

+

–

ENC

0.1µF

225814 F12

T1: COILCRAFT WBC4 - 1WL

D1: AVAGO HSMS - 2822

ENC

RESISTORS, CAPACITORS ARE 0402 PACKAGE SIZE

Figure 12. Sinusoidal Encode Drive

225814 F10

Figure 10. Equivalent Encode Input Circuit

for Differential Encode Mode

0.1µF

+

ENC

LTC2258-14

+

1.8V TO 3.3V

0V

ENC

PECL OR

LTC2258-14

LVDS

–

CLOCK

30k

ENC

0.1µF

–

CMOS LOGIC

BUFFER

ENC

225814 F11

225814 F13

Figure 11. Equivalent Encode Input Circuit

for Single-Ended Encode Mode

Figure 13. PECL or LVDS Encode Drive

225814fc

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by mode control register A2 (serial programming mode),

For good performance the digital outputs should drive

minimal capacitive loads. If the load capacitance is larger

than 10pF a digital buffer should be used.

or by CS (parallel programming mode).

Forapplicationswherethesamplerateneedstobechanged

quickly, the clock duty cycle stabilizer can be disabled. If

the duty cycle stabilizer is disabled, care should be taken

to make the sampling clock have a 50%( 5%) duty cycle.

The duty cycle stabilizer should not be used below 5Msps.

Double Data Rate LVDS Mode

In double data rate LVDS mode, two data bits are

multiplexed and output on each differential output pair.

+

–

There are 7 LVDS output pairs (D0_1 /D0_1 through

+

–

D12_13 /D12_13 ) for the digital output data. Overflow

(OF /OF )andthedataoutputclock(CLKOUT /CLKOUT )

each have an LVDS output pair.

+

–

+

–

DIGITAL OUTPUTS

Digital Output Modes

By default the outputs are standard LVDS levels: 3.5mA

output current and a 1.25V output common mode volt-

age. An external 100Ω differential termination resistor

is required for each LVDS output pair. The termination

resistors should be located as close as possible to the

LVDS receiver.

TheLTC2258-14/LTC2257-14/LTC2256-14canoperatein

three digital output modes: full rate CMOS, double data

rateCMOS(tohalvethenumberofoutputlines), ordouble

data rate LVDS (to reduce digital noise in the system). The

output mode is set by mode control register A3 (serial

programming mode), or by SCK (parallel programming

mode).NotethatdoubledatarateCMOScannotbeselected

in the parallel programming mode.

The outputs are powered by OV and OGND which are

DD

isolated from the A/D core power and ground. In LVDS

mode, OV must be 1.8V.

DD

Full-Rate CMOS Mode

Programmable LVDS Output Current

In full-rate CMOS mode the 14 digital outputs (D0-D13),

+

In LVDS mode, the default output driver current is 3.5mA.

Thiscurrentcanbeadjustedbyseriallyprogrammingmode

control register A3. Available current levels are 1.75mA,

2.1mA, 2.5mA, 3mA, 3.5mA, 4mA and 4.5mA.

overflow (OF), and the data output clocks (CLKOUT ,

–

CLKOUT ) have CMOS output levels. The outputs are

powered by OV and OGND which are isolated from the

DD

A/D core power and ground. OV can range from 1.1V

DD

to 1.9V, allowing 1.2V through 1.8V CMOS logic outputs.

Optional LVDS Driver Internal Termination

For good performance, the digital outputs should drive

minimal capacitive loads. If the load capacitance is larger

than 10pF a digital buffer should be used.

In most cases using just an external 100Ω termination

resistor will give excellent LVDS signal integrity. In addi-

tion, an optional internal 100Ω termination resistor can

beenabledbyseriallyprogrammingmodecontrolregister

A3. The internal termination helps absorb any reflections

caused by imperfect termination at the receiver. When the

internal termination is enabled, the output driver current

is increased by 1.6x to maintain about the same output

voltage swing.

Double Data Rate CMOS Mode

In double data rate CMOS mode, two data bits are

multiplexed and output on each data pin. This reduces the

number of data lines by seven, simplifying board routing

and reducing the number of input pins needed to receive

the data. The 7 digital outputs (D0_1, D2_3, D4_5, D6_7,

D8_9, D10_11, D12_13), overflow (OF), and the data

output clocks (CLKOUT , CLKOUT ) have CMOS output

levels. TheoutputsarepoweredbyOV andOGNDwhich

are isolated from the A/D core power and ground. OV

Overflow Bit

+

–

The overflow output bit (OF) outputs a logic high when

the analog input is either overranged or underranged. The

overflow bit has the same pipeline latency as the data bits.

DD

can range from 1.1V to 1.9V, allowing 1.2V through 1.8V

CMOS logic outputs.

225814fc

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Phase Shifting the Output Clock

DATA FORMAT

In full-rate CMOS mode the data output bits normally

Table 1 shows the relationship between the analog input

voltage, the digital data output bits and the overflow bit.

By default the output data format is offset binary. The 2’s

complement format can be selected by serially program-

ming mode control register A4.

+

change at the same time as the falling edge of CLKOUT ,

+

so the rising edge of CLKOUT can be used to latch the

output data. In double data rate CMOS and LVDS modes

the data output bits normally change at the same time as

+

thefallingandrisingedgesofCLKOUT .To allowadequate

Table 1. Output Codes vs Input Voltage

+

setup-and-hold time when latching the data, the CLKOUT

+

–

A

IN

– A

D13-D0

IN

signal may need to be phase shifted relative to the data

outputbits. MostFPGAshavethisfeature;thisisgenerally

the best place to adjust the timing.

(2V Range)

>1.000000V

+0.999878V

+0.999756V

+0.000122V

+0.000000V

–0.000122V

–0.000244V

–0.999878V

–1.000000V

≤–1.000000V

OF (OFFSET BINARY)

(2’s COMPLEMENT)

1

0

1

11 1111 1111 1111

11 1111 1111 1110

10 0000 0000 0001

10 0000 0000 0000

01 1111 1111 1111

01 1111 1111 1110

00 0000 0000 0001

00 0000 0000 0000

01 1111 1111 1111

01 1111 1111 1110

00 0000 0000 0001

00 0000 0000 0000

11 1111 1111 1111

11 1111 1111 1110

10 0000 0000 0001

10 0000 0000 0000

TheLTC2258-14/LTC2257-14/LTC2256-14canalsophase

+

–

shift the CLKOUT /CLKOUT signals by serially program-

ming mode control register A2. The output clock can be

shifted by 0°, 45°, 90° or 135°. To use the phase shifting

feature the clock duty cycle stabilizer must be turned

on. Another control register bit can invert the polarity of

+

–

CLKOUT and CLKOUT , independently of the phase shift.

Thecombinationofthesetwofeaturesenablesphaseshifts

of 45° up to 315° (Figure 14).

+

ENC

D0-D13, OF

MODE CONTROL BITS

PHASE

SHIFT

CLKINV

CLKPHASE1 CLKPHASE0

0°

0

1

0

1

0

1

0

1

0

1

0

1

0

1

45°

90°

135°

180°

225°

270°

315°

+

CLKOUT

225814 F14

Figure 14. Phase Shifting CLKOUT

225814fc

23

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Digital Output Randomizer

Alternate Bit Polarity

Interference from the A/D digital outputs is sometimes

unavoidable.Digitalinterferencemaybefromcapacitiveor

inductive coupling or coupling through the ground plane.

Even a tiny coupling factor can cause unwanted tones

in the ADC output spectrum. By randomizing the digital

output before it is transmitted off chip, these unwanted

tones can be randomized which reduces the unwanted

tone amplitude.

Anotherfeaturethatreducesdigitalfeedbackonthecircuit

board is the alternate bit polarity mode. When this mode

is enabled, all of the odd bits (D1, D3, D5, D7, D9, D11,

D13) are inverted before the output buffers. The even bits

(D0, D2, D4, D6, D8, D10, D12), OF and CLKOUT are not

affected. This can reduce digital currents in the circuit

board ground plane and reduce digital noise, particularly

for very small analog input signals.

The digital output is “randomized” by applying an

exclusive-OR logic operation between the LSB and all

other data output bits. To decode, the reverse opera-

tion is applied—an exclusive-OR operation is applied

between the LSB and all other bits. The LSB, OF and

CLKOUT outputs are not affected. The output random-

izer is enabled by serially programming mode control

register A4.

When there is a very small signal at the input of the A/D

thatiscenteredaroundmid-scale,thedigitaloutputstoggle

between mostly 1s and mostly 0s. This simultaneous

switchingofmostofthebitswillcauselargecurrentsinthe

ground plane. By inverting every other bit, the alternate bit

polarity mode makes half of the bits transition high while

half of the bits transition low. To first order, this cancels

currentflowinthegroundplane,reducingthedigitalnoise.

PC BOARD

FPGA

CLKOUT

OF

D13/D0

D13

D13/D0

D12/D0

D13

D12

D12/D0

D12

D2

LTC2258-14

•

D2/D0

D1/D0

D2/D0

D1/D0

D2

D1

D0

RANDOMIZER

ON

D1

D0

225814 F16

225814 F15

Figure 15. Functional Equivalent of Digital Output Randomizer

Figure 16. Unrandomizing a Randomized Digital

Output Signal

225814fc

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The digital output is decoded at the receiver by invert-

ing the odd bits (D1, D3, D5, D7, D9, D11, D13.) The

alternate bit polarity mode is independent of the digital

output randomizer—either, both or neither function

can be on at the same time. When alternate bit polarity

mode is on, the data format is offset binary and the 2’s

complement control bit has no effect. The alternate bit

polarity mode is enabled by serially programming mode

control register A4.

depends on the size of the bypass capacitors on V

REFH, and REFL. For the suggested values in Figure 8,

the A/D will stabilize after 2ms.

,

REF

In nap mode the A/D core is powered down while the

internal reference circuits stay active, allowing faster

wake-up than from sleep mode. Recovering from nap

mode requires at least 100 clock cycles. If the applica-

tion demands very accurate DC settling then an additional

50µs should be allowed so the on-chip references can

settle from the slight temperature shift caused by the

change in supply current as the A/D leaves nap mode.

Nap mode is enabled by mode control register A1 in the

serial programming mode.

Digital Output Test Patterns

To allow in-circuit testing of the digital interface to the

A/D, there are several test modes that force the A/D data

outputs (OF, D13-D0) to known values:

All 1s: All outputs are 1

All 0s: All outputs are 0

DEVICE PROGRAMMING MODES

The operating modes of the LTC2258-14/LTC2257-14/

LTC2256-14 can be programmed by either a parallel

interface or a simple serial interface. The serial interface

has more flexibility and can program all available modes.

Theparallelinterfaceismorelimitedandcanonlyprogram

some of the more commonly used modes.

Alternating: Outputs change from all 1s to all 0s on

alternating samples

Checkerboard:Outputschangefrom101010101010101

to 010101010101010 on alternating samples

The digital output test patterns are enabled by serially

programming mode control register A4. When enabled,

the test patterns override all other formatting modes: 2’s

complement, randomizer, alternate-bit-polarity.

Parallel Programming Mode

To use the parallel programming mode, PAR/SER should

be tied to V . The CS, SCK and SDI pins are binary logic

DD

inputs that set certain operating modes. These pins can

Output Disable

be tied to V or ground, or driven by 1.8V, 2.5V or 3.3V

DD

CMOS logic. Table 2 shows the modes set by CS, SCK

The digital outputs may be disabled by serially program-

mingmodecontrolregisterA3.Alldigitaloutputsincluding

OFandCLKOUTaredisabled.Thehighimpedancedisabled

state is intended for long periods of inactivity—it is too

slow to multiplex a data bus between multiple converters

at full speed.

and SDI.

Table 2. Parallel Programming Mode Control Bits (PAR/SER = V_DD

)

DESCRIPTION

CS

Clock Duty Cycle Stabilizer Control Bit

0 = Clock Duty Cycle Stabilizer Off

1 = Clock Duty Cycle Stabilizer On

Digital Output Mode Control Bit

0 = Full-Rate CMOS Output Mode

Sleep and Nap Modes

SCK

SDI

The A/D may be placed in sleep or nap modes to conserve

power. In sleep mode the entire A/D converter is powered

down,resultingin0.5mWpowerconsumption.Sleepmode

is enabled by mode control register A1 (serial program-

ming mode), or by SDI (parallel programming mode).

The amount of time required to recover from sleep mode

1 = Double Data Rate LVDS Output Mode

(3.5mA LVDS Current, Internal Termination Off)

Power Down Control Bit

0 = Normal Operation

1 = Sleep Mode

225814fc

25

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Serial Programming Mode

diagrams). During a read back command the register is

not updated and data on SDI is ignored.

To use the serial programming mode, PAR/SER should be

tied to ground. The CS, SCK, SDI and SDO pins become a

serialinterfacethatprogramtheA/Dmodecontrolregisters.

Data is written to a register with a 16-bit serial word. Data

can also be read back from a register to verify its contents.

The SDO pin is an open-drain output that pulls to ground

with a 200Ω impedance. If register data is read back

through SDO, an external 2k pull-up resistor is required. If

serialdataisonlywrittenandreadbackisnotneeded, then

SDO can be left floating and no pull-up resistor is needed.

Serial data transfer starts when CS is taken low. The data

on the SDI pin is latched at the first 16 rising edges of

SCK. Any SCK rising edges after the first 16 are ignored.

The data transfer ends when CS is taken high again.

Table 3 shows a map of the mode control registers.

Software Reset

If serial programming is used, the mode control registers

shouldbeprogrammedassoonaspossibleafterthepower

supplies turn on and are stable. The first serial command

must be a software reset which will reset all register data

bits to logic 0. To perform a software reset, bit D7 in the

reset register is written with a logic 1. After the reset SPI

write command is complete, bit D7 is automatically set

back to zero.

The first bit of the 16-bit input word is the R/W bit. The

next seven bits are the address of the register (A6:A0).

The final eight bits are the register data (D7:D0).

If the R/W bit is low, the serial data (D7:D0) will be writ-

ten to the register set by the address bits (A6:A0). If the

R/W bit is high, data in the register set by the address bits

(A6:A0) will be read back on the SDO pin (see the timing

Table 3. Serial Programming Mode Register Map

REGISTER A0: RESET REGISTER (ADDRESS 00h)

D7

D6

X

D5

D4

X

D3

X

D2

X

D1

X

D0

X

RESET

X

Bit 7

RESET

0 = Not Used

Software Reset Bit

1 = Software Reset. All Mode Control Registers are Reset to 00h. This Bit is Automatically Set Back to Zero at the end of the SPI

Write Command.

The Reset Register is Write Only.

Bits 6-0

Unused, Don’t Care Bits.

REGISTER A1: POWER-DOWN REGISTER (ADDRESS 01h)

D7

X

D6

D5

X

D4

X

D3

X

D2

X

D1

D0

X

PWROFF1

PWROFF0

Bits 7-2

Unused, Don’t Care Bits.

Bits 1-0

PWROFF1:PWROFF0

00 = Normal Operation

01 = Nap Mode

Power Down Control Bits

10 = Not Used

11 = Sleep Mode

225814fc

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REGISTER A2: TIMING REGISTER (ADDRESS 02h)

D7

X

D6

D5

X

D4

X

D3

D2

D1

D0

X

CLKINV

CLKPHASE1

CLKPHASE0

DCS

Bits 7-4

Unused, Don’t Care Bits.

Bit 3

CLKINV

Output Clock Invert Bit

0 = Normal CLKOUT Polarity (As Shown in the Timing Diagrams)

1 = Inverted CLKOUT Polarity

Bits 2-1

CLKPHASE1:CLKPHASE0

Output Clock Phase Delay Bits

00 = No CLKOUT Delay (As Shown in the Timing Diagrams)

+

–

01 = CLKOUT /CLKOUT Delayed by 45° (Clock Period • 1/8)

10 = CLKOUT /CLKOUT Delayed by 90° (Clock Period • 1/4)

11 = CLKOUT /CLKOUT Delayed by 135° (Clock Period • 3/8)

Note: If the CLKOUT Phase Delay Feature is Used, the Clock Duty Cycle Stabilizer Must Also be Turned On

Bit 0

DCS

Clock Duty Cycle Stabilizer Bit

0 = Clock Duty Cycle Stabilizer Off

1 = Clock Duty Cycle Stabilizer On

REGISTER A3: OUTPUT MODE REGISTER (ADDRESS 03h)

D7

X

D6

D5

D4

D3

D2

D1

D0

ILVDS2

ILVDS1

ILVDS0

TERMON

OUTOFF

OUTMODE1

OUTMODE0

Bit 7

Unused, Don’t Care Bit.

Bits 6-4

ILVDS2:ILVDS0 LVDS Output Current Bits

000 = 3.5mA LVDS Output Driver Current

001 = 4.0mA LVDS Output Driver Current

010 = 4.5mA LVDS Output Driver Current

011 = Not Used

100 = 3.0mA LVDS Output Driver Current

101 = 2.5mA LVDS Output Driver Current

110 = 2.1mA LVDS Output Driver Current

111 = 1.75mA LVDS Output Driver Current

Bit 3

TERMON

0 = Internal Termination Off

1 = Internal Termination On. LVDS Output Driver Current is 1.6× the Current Set by ILVDS2:ILVDS0

LVDS Internal Termination Bit

Bit 2

OUTOFF

Output Disable Bit

0 = Digital Outputs are Enabled

1 = Digital Outputs are Disabled and Have High Output Impedance

Bits 1-0

OUTMODE1:OUTMODE0

Digital Output Mode Control Bits

00 = Full-Rate CMOS Output Mode

01 = Double Data Rate LVDS Output Mode

10 = Double Data Rate CMOS Output Mode

11 = Not Used

225814fc

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REGISTER A4: DATA FORMAT REGISTER (ADDRESS 04h)

D7

X

D6

X

D5

D4

D3

D2

D1

D0

OUTTEST2

OUTTEST1

OUTTEST0

ABP

RAND

TWOSCOMP

Bit 7-6

Unused, Don’t Care Bits.

Bits 5-3

OUTTEST2:OUTTEST0

Digital Output Test Pattern Bits

000 = Digital Output Test Patterns Off

001 = All Digital Outputs = 0

011 = All Digital Outputs = 1

101 = Checkerboard Output Pattern. OF, D13-D0 Alternate Between 101 0101 0101 0101 and 010 1010 1010 1010

111 = Alternating Output Pattern. OF, D13-D0 Alternate Between 000 0000 0000 0000 and 111 1111 1111 1111

Note: Other Bit Combinations are not Used

Bit 2

Bit 1

Bit 0

ABP

Alternate Bit Polarity Mode Control Bit

0 = Alternate Bit Polarity Mode Off

1 = Alternate Bit Polarity Mode On

RAND

Data Output Randomizer Mode Control Bit

0 = Data Output Randomizer Mode Off

1 = Data Output Randomizer Mode On

TWOSCOMP Two’s Complement Mode Control Bit

0 = Offset Binary Data Format

1 = Two’s Complement Data Format

Note: ABP = 1 Forces the Output Format to be Offset Binary

GROUNDING AND BYPASSING

The V capacitor should be located as close to the pin

CM

as possible. To make space for this the capacitor on V

REF

The LTC2258-14/LTC2257-14/LTC2256-14 requires a

printed circuit board with a clean unbroken ground plane.

A multilayer board with an internal ground plane is rec-

ommended. Layout for the printed circuit board should

ensure that digital and analog signal lines are separated as

much as possible. In particular, care should be taken not

to run any digital track alongside an analog signal track

or underneath the ADC.

can be further away or on the back of the PC board. The

traces connecting the pins and bypass capacitors must

be kept short and should be made as wide as possible.

The analog inputs, encode signals, and digital outputs

should not be routed next to each other. Ground fill and

grounded vias should be used as barriers to isolate these

signals from each other.

High quality ceramic bypass capacitors should be used at

HEAT TRANSFER

the V , OV , V , V , REFH and REFL pins. Bypass

DD

DD CM REF

capacitorsmustbelocatedasclosetothepinsaspossible.

Of particular importance is the 0.1µF capacitor between

REFH and REFL. This capacitor should be on the same

side of the circuit board as the A/D, and as close to the

device as possible (1.5mm or less). Size 0402 ceramic

capacitors are recommended. The larger 2.2µF capacitor

between REFH and REFL can be somewhat further away.

Most of the heat generated by the ADC is transferred from

the diethrough the bottom-side exposed pad and package

leadsontotheprintedcircuitboard.Forgoodelectricaland

thermal performance, the exposed pad must be soldered

to a large grounded pad on the PC board.

225814fc

28

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical applicaTions

LTC2258 Schematic

T2

MABAES0060

R9 10Ω

SENSE

•

C23

1µF

R39

ANALOG INPUT

33.2Ω

1%

R14

1k

C51

4.7pF

R40

33.2Ω

1%

C17

1µF

R10 10Ω

R16

100Ω

R15 100Ω

V

DD

C12

0.1µF

C13

1µF

C19

0.1µF

DIGITAL

OUTPUTS

40

39

38

37

36

+

35

–

34

33

32

31

V

SENSE V

V

CM

OF

OF D13 D12 D11 D10

DD

REF

R27 10Ω

R28 10Ω

1

2

30

29

28

27

26

25

24

23

22

21

+

–

AIN

D9

AIN

D8

+

3

GND

CLKOUT

4

–

REFH

REFL

CLKOUT

U2

LTC2258CUJ

5

C15

0.1µF

0V

OV

DD

C20

2.2µF

C37

0.1µF

6

OGND

7

D7

D6

D5

D4

8

PAR/SER

C21

0.1µF

PAR/SER

9

V

DD

10

V

DD

V

C18

0.1µF

+

–

GND ENC ENC CS SCK SDI SDO D0 D1 D2 D3

DIGITAL

OUTPUTS

41

11

12

13

14

15

16

17

18

19

20

R13

100Ω

ENCODE CLOCK

225814 TA02

SPI BUS

225814fc

29

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical applicaTions

Top Side

Silkscreen Top

225814 TA04

225814 TA03

Inner Layer 2 GND

Inner Layer 3

225814 TA04

225814 TA06

225814fc

30

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

Typical applicaTions

Inner Layer 4

Inner Layer 5 Power

225814 TA08

225814 TA07

Bottom Side

225814 TA09

225814fc

31

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

package DescripTion

Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.

UJ Package

40-Lead Plastic QFN (6mm × 6mm)

(Reference LTC DWG # 05-08-1728 Rev Ø)

0.70 0.05

6.50 0.05

5.ꢀ0 0.05

4.42 0.05

4.50 0.05

(4 SIDES)

4.42 0.05

PACKAGE OUTLINE

0.25 0.05

0.50 BSC

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED

0.75 0.05

R = 0.ꢀꢀ5

TYP

6.00 0.ꢀ0

(4 SIDES)

R = 0.ꢀ0

TYP

39 40

0.40 0.ꢀ0

PIN ꢀ TOP MARK

(SEE NOTE 6)

ꢀ

2

PIN ꢀ NOTCH

R = 0.45 OR

0.35 × 45°

CHAMFER

4.42 0.ꢀ0

4.50 REF

(4-SIDES)

4.42 0.ꢀ0

(UJ40) QFN REV Ø 0406

0.200 REF

0.25 0.05

0.50 BSC

0.00 – 0.05

NOTE:

BOTTOM VIEW—EXPOSED PAD

ꢀ. DRAWING IS A JEDEC PACKAGE OUTLINE VARIATION OF (WJJD-2)

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE, IF PRESENT

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN ꢀ LOCATION ON THE TOP AND BOTTOM OF PACKAGE

225814fc

32

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

revision hisTory ^{(Revision history begins at Rev B)}

REV

DATE

DESCRIPTION

PAGE NUMBER

B

08/12 Corrected IO

to I

11, 12, 14

VDD

OVDD

Corrected RESET REGISTER A0, D7 description

26

29

20

Attached V to pins 9, 10 and 40 on schematic

DD

C

1/14

Corrected "external reference” to "internal reference” for 1V input range.

225814fc

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

33

For more information www.linear.com/LTC2258-14

LTC2258-14

LTC2257-14/LTC2256-14

relaTeD parTs

PART NUMBER DESCRIPTION

COMMENTS

LT1993-2

LT1994

High Speed Differential Op Amp

800MHz BW, 70dBc Distortion at 70MHz, 6dB Gain

Low Distortion: –94dBc at 1MHz

Low Noise, Low Distortion Fully Differential Input/

Output Amplifier/Driver

LTC2202

LTC2203

LTC2204

LTC2205

LTC2206

LTC2207

LTC2208

LTC2209

LTC2220

LTC2220-1

LTC2224

LTC2249

LTC2250

LTC2251

LTC2252

LTC2253

LTC2254

LTC2255

16-Bit, 10Msps, 3.3V ADC, Lowest Noise

16-Bit, 25Msps, 3.3V ADC, Lowest Noise

16-Bit, 40Msps, 3.3V ADC

140mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN

220mW, 81.6dB SNR, 100dB SFDR, 48-Pin QFN

480mW, 79dB SNR, 100dB SFDR, 48-Pin QFN

590mW, 79dB SNR, 100dB SFDR, 48-Pin QFN

725mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN

900mW, 77.9dB SNR, 100dB SFDR, 48-Pin QFN

1250mW, 77.7dB SNR, 100dB SFDR, 64-Pin QFN

1450mW, 77.1dB SNR, 100dB SFDR, 64-Pin QFN

890mW, 67.5dB SNR, 9mm × 9mm QFN Package

910mW, 67.7dB SNR, 80dB SFDR, 64-Pin QFN

630mW, 67.6dB SNR, 84dB SFDR, 48-Pin QFN

230mW, 73dB SNR, 5mm × 5mm QFN Package

320mW, 61.6dB SNR, 5mm × 5mm QFN Package

395mW, 61.6dB SNR, 5mm × 5mm QFN Package

320mW, 70.2dB SNR, 5mm × 5mm QFN Package

395mW, 70.2dB SNR, 5mm × 5mm QFN Package

320mW, 72.5dB SNR, 5mm × 5mm QFN Package

395mW, 72.5dB SNR, 88dB SFDR, 32-Pin QFN

16-Bit, 65Msps, 3.3V ADC

16-Bit, 80Msps, 3.3V ADC

16-Bit, 105Msps, 3.3V ADC

16-Bit, 130Msps, 3.3V ADC, LVDS Outputs

16-Bit, 160Msps, 3.3V ADC, LVDS Outputs

12-Bit, 170Msps ADC

12-Bit, 185Msps, 3.3V ADC, LVDS Outputs

12-Bit, 135Msps, 3.3V ADC, High IF Sampling

14-Bit, 80Msps ADC

10-Bit, 105Msps ADC

10-Bit, 125Msps ADC

12-Bit, 105Msps ADC

12-Bit, 125Msps ADC

14-Bit, 105Msps ADC

14-Bit, 125Msps, 3V ADC, Lowest Power

12-Bit, 25/40/65Msps 1.8V ADCs, Ultralow Power

LTC2256-12/

LTC2257-12/

LTC2258-12

34mW/47mW/79mW, 71.1dB SNR, 88dB SFDR, DDR LVDS/DDR CMOS/

CMOS Outputs, 6mm × 6mm QFN Package

LTC2259-12/

LTC2260-12/

LTC2261-12

12-Bit, 80/105/125Msps 1.8V ADCs, Ultralow

Power

87mW/103mW/124mW, 70.8dB SNR, 85dB SFDR, DDR LVDS/DDR CMOS/

CMOS Outputs, 6mm × 6mm QFN Package

LTC2259-14/

LTC2260-14/

LTC2261-14

14-Bit, 80/105/125Msps 1.8V ADCs, Ultralow

Power

89mW/106mW/127mW, 73.4dB SNR, 85dB SFDR, DDR LVDS/DDR CMOS/

CMOS Outputs, 6mm × 6mm QFN Package

LTC2284

LTC2299

LT5517

14-Bit, Dual, 105Msps, 3V ADC, Low Crosstalk

Dual 14-Bit, 80Msps ADC

540mW, 72.4dB SNR, 88dB SFDR, 64-Pin QFN

230mW, 71.6dB SNR, 5mm x 5mm QFN Package

High IIP3: 21dBm at 800MHz, Integrated LO Quadrature Generator

40MHz to 900MHz Direct Conversion Quadrature

Demodulator

LT5527

400MHz to 3.7GHz High Linearity Downconverting

Mixer

24.5dBm IIP3 at 900MHz, 23.5dBm IIP3 at 3.5GHz, NF = 12.5dB,

50Ω Single-Ended RF and LO Ports

LT5557

400MHz to 3.8GHz High Linearity Downconverting

Mixer

23.7dBm IIP3 at 2.6GHz, 23.5dBm IIP3 at 3.5GHz, NF = 13.2dB,

3.3V Supply Operation, Integrated Transformer

LT5575

800MHz to 2.7GHz Direct Conversion Quadrature

Demodulator

High IIP3: 28dBm at 900MHz, Integrated LO Quadrature Generator

Integrated RF and LO Transformer

LTC6400-20

1.8GHz Low Noise, Low Distortion Differential ADC Fixed Gain 10V/V, 2.1nV√Hz Total Input Noise, 3mm × 3mm QFN-16 Package

Driver for 300MHz IF

LT6604-2.5/

LT6604-5/

LT6604-10/

LT6604-15

Dual Matched 2.5MHz, 5MHz, 10MHz, 15MHz Filter Dual Matched 4th Order LP Filters with Differential Drivers. Low Noise, Low

with ADC Driver

Distortion Amplifiers

225814fc

LT 0114 REV C • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

34

For more information www.linear.com/LTC2258-14

●

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LTC2257-14_15
厂家：	Linear
描述：	14-Bit, 65/40/25Msps Ultralow Power 1.8V ADCs
文件：	总34页 (文件大小：1355K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTC2257-14_15 [Linear]

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