MAX5494_技术文档

19-3562; Rev 2; 1/06

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

General Description

Features

♦ Wiper Position Stored in Nonvolatile Memory and

The MAX5494–MAX5499 10-bit (1024-tap), dual, non-

volatile, linear-taper, programmable voltage-dividers

and variable resistors perform the function of a

mechanical potentiometer, but replace the mechanics

with a 3-wire SPI™-compatible serial interface. The

MAX5494/MAX5495 are dual, 3-terminal, programma-

ble voltage-dividers; the MAX5496/MAX5497 are dual,

2-terminal variable resistors; and the MAX5498/

MAX5499 include one 2-terminal variable resistor and

one 3-terminal programmable voltage-divider.

Recalled Upon Power-Up

♦ 16-Pin, 5mm x 5mm x 0.8mm TQFN Package

♦ 35ppm/°C End-to-End Resistance Temperature

Coefficient

♦ 5ppm/°C Ratiometric Temperature Coefficient

♦ 10kΩ and 50kΩ End-to-End Resistor Values

♦ 3-Wire SPI-Compatible Serial Interface

The MAX5494–MAX5499 feature an internal, nonvolatile,

electrically erasable programmable read-only memory

(EEPROM) that stores the wiper position for initialization

during power-up. The 3-wire SPI-compatible serial inter-

face allows communication at data rates up to 7MHz.

♦ Reliability (T = +85°C)

A

50,000 Wiper Store Cycles

50 Years Wiper Data Retention

♦ 1.5µA (max) Standby Current

The MAX5494–MAX5499 are ideal for applications requir-

ing digitally controlled potentiometers. End-to-end resis-

tance values of 10kΩ and 50kΩ are available with a

35ppm/°C end-to-end temperature coefficient. The ratio-

metric temperature coefficient is 5ppm/°C for each chan-

nel, making these devices ideal for applications requiring

low-temperature-coefficient programmable voltage-

dividers such as low-drift, programmable-gain amplifiers.

♦ Single +2.7V to +5.25V Supply Operation

♦ Dual 2.5V Supply Operation

Pin Configurations

TOP VIEW

12

11

10

9

The MAX5494–MAX5499 operate with either a single

power supply (+2.7V to +5.25V) or dual power supplies

( 2.5V). The devices consume 400ꢀA (maꢁ) of supply

current when writing data to the nonvolatile memory

and 1.5ꢀA (maꢁ) of standby supply current. The

devices are available in space-saving (5mm ꢁ 5mm ꢁ

0.8mm), 16-pin TQFN package and are specified over

the eꢁtended (-40°C to +85°C) temperature range.

DIN 13

V

SS

8

7

6

5

N.C.

14

15

N.C.

MAX5494

MAX5495

SCLK 16

V

DD

1

2

3

4

Applications

Gain and Offset Adjustment

5mm × 5mm × 0.8mm TQFN

LCD Contrast Adjustment

Pressure Sensors

12

11

10

9

Low-Drift Programmable-Gain Amplifiers

Mechanical Potentiometer Replacement

Volume Control

DIN 13

V

SS

8

7

6

5

N.C.

14

15

N.C.

MAX5496

MAX5497

Ordering Information

PIN-

PACKAGE

PART

TEMP RANGE

PKG CODE

SCLK 16

V

DD

MAX5494ETE -40°C to +85°C 16 TQFN-EP*

MAX5495ETE -40°C to +85°C 16 TQFN-EP*

*EP = Eꢁposed pad.

T1655-2

1

2

3

4

Ordering Information continued at end of data sheet.

Selector Guide appears at end of data sheet.

SPI is a trademark of Motorola, Inc.

5mm × 5mm × 0.8mm TQFN

Pin Configurations continued at end of data sheet.

________________________________________________________________ Maxim Integrated Products

1

For pricing delivery, and ordering information please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

ABSOLUTE MAXIMUM RATINGS

V

to GND...........................................................-0.3V to +6.0V

to GND............................................................-3.5V to +0.3V

Continuous Power Dissipation (T = +70°C)

A

DD

SS

DD

16-Pin TQFN (derate 20.8mW/°C above +70°C) ....1666.7mW

Operating Temperature Range ...........................-40°C to +85°C

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

Storage Temperature Range.............................-60°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

to V .............................................................-0.3V to +6.0V

SS

H1, H2, L1, L2, W1, W2 to V .........(V - 0.3V) to (V

+ 0.3V)

SS

DD

CS, SCLK, DIN to GND ..............................-0.3V to (V

Maꢁimum Continuous Current into H_, L_, and W_

MAX5494/MAX5496/MAX5498.................................... 5.0mA

MAX5495/MAX5497/MAX5499.................................... 1.0mA

Maꢁimum Current Into Other Pins ................................. 50.0mA

Stresses beyond those listed under “Absolute Maꢁimum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Eꢁposure to

absolute maꢁimum rating conditions for eꢁtended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS

(V

= +2.7V to +5.25V, V = GND = 0, V = V , V = 0, T = -40°C to +85°C, unless otherwise noted. Typical values are at

DD

SS

H_

DD L_

A

V

DD

= +5.0V, T = +25°C.) (Note 1)

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

–MAX549

DC PERFORMANCE (MAX5494/MAX5495/MAX5498/MAX5499 Programmable Voltage-Divider)

Resolution

N

10

Bits

V

= 2.7V

= 5V

2

1

DD

Integral Nonlinearity (Note 2)

INL

LSB

= 2.7V

= 5V

Differential Nonlinearity (Note 2)

DNL

LSB

ppm/°C

LSB

End-to-End Resistance

Temperature Coefficient

TC

35

5

R

Ratiometric Temperature

Coefficient

MAX5494/MAX5498

MAX5495/MAX5499

MAX5494/MAX5498

MAX5495/MAX5499

-4

0

-2.5

-0.75

3.3

0

5

Full-Scale Error

FSE

ZSE

Zero-Scale Error

LSB

pF

0

1.45

60

Wiper Capacitance

End-to-End Resistance

C

W

MAX5494/MAX5498

MAX5495/MAX5499

7.5

10

12.5

62.5

R

kΩ

HL

37.5

50

MAX5494

MAX5495

0.05

0.15

Channel-to-Channel Division

Ratio Matching

V

= 3V, midcode: 512

%

DD

MAX5494/MAX5498, W_ at 15 code, H_ and

L_ shorted to V , measure resistance from

SS

W_ to H_ (Figures 4 and 5)

6.3

25

Resistance from W_ to L_ and H_

kΩ

MAX5495/MAX5499, W_ at 15 code, H_ and

L_ shorted to V , measure resistance from

SS

W_ to H_ (Figures 4 and 5)

2

_______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

ELECTRICAL CHARACTERISTICS (continued)

(V

= +2.7V to +5.25V, V = GND = 0, V = V , V = 0, T = -40°C to +85°C, unless otherwise noted. Typical values are at

DD

SS

H_

DD L_

A

V

DD

= +5.0V, T = +25°C.) (Note 1)

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Bits

DC PERFORMANCE (MAX5496–MAX5499 Variable Resistor)

Resolution

N

10

V

= 2.7V

= 3V

-1.6

-1.4

DD

Integral Nonlinearity (Note 3)

INL_R

-4

+4

LSB

= 5V

-1.3

= 2.7V

= 3V

+0.45

+0.4

+0.35

Differential Nonlinearity (Note 3)

DNL_R

-1

+1

LSB

= 5V

Variable-Resistor Temperature

Coefficient

TC

V

= 3V to 5.25V; code = 128 to 1024

35

ppm/°C

VR

DD

Wiper Resistance

Wiper Capacitance

R

≥ 3V (Note 4)

50

60

Ω

W

C

pF

WR

MAX5496/MAX5498

MAX5497/MAX5499

7.5

10

12.5

62.5

Full-Scale Wiper-to-End

Resistance

R

W-L

kΩ

37.5

50

MAX5494/MAX5498

MAX5495/MAX5499

70

Zero-Scale Resistor Error

R

Code = 0

Ω

Z

110

MAX5496/MAX5498,

Code >128

0.1

Two-Channel Resistance

Matching

V

= 3V to 5.25V

%

DD

MAX5497/MAX5499,

Code >200

0.15

DIGITAL INPUTS (CS, SCLK, DIN) (Note 5)

V

= 3.6V to 5.25V

= 2.7V to 3.6V

2.4

DD

Single-supply

operation

0.7 ꢁ

V

Input High Voltage

Input Low Voltage

V

DD

IH

With respect to

GND, V = 2.5V,

V

Dual-supply

operation

2.0

DD

= -2.5V

SS

Single-supply

operation

V

= 2.7V to 5.25V

0.8

DD

V

IL

With respect to

GND, V = 2.5V,

V

Dual-supply

operation

0.6

1

DD

= -2.5V

SS

Input Leakage Current

Input Capacitance

I

ꢀA

pF

IN

C

5

IN

DYNAMIC CHARACTERISTICS

Wiper at code 495

(01111 01111), 10pF

load at wiper

MAX5494/MAX5498

MAX5495/MAX5499

250

50

Wiper -3dB Bandwidth

BW

kHz

_______________________________________________________________________________________

3

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

ELECTRICAL CHARACTERISTICS (continued)

(V

= +2.7V to +5.25V, V = GND = 0, V = V , V = 0, T = -40°C to +85°C, unless otherwise noted. Typical values are at

DD

SS

H_

DD L_

A

V

DD

= +5.0V, T = +25°C.) (Note 1)

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

MAX5494/MAX5498; V

= 3V; wiper at

DD

code 495; 10kHz, 1V

signal is applied

0.026

RMS

at H_; 10pF load at wiper

Total Harmonic Distortion

Analog Crosstalk

THD

%

MAX5495/MAX5499; V

code 495; 10kHz, 1V

= 3V; wiper at

signal is applied

DD

0.03

-93

RMS

at H_; 10pF load at wiper

CH2 = 11111 11111, CH1 = 01111 01111,

C

= 10pF, V = V

= +2.5V,

DD

W_

L1

H1

dB

V

= V = -2.5V, measure V

with

SS

W1

= 5V

at f = 1kHz

W2

P-P

NONVOLATILE MEMORY RELIABILITY

–

Data Retention

T

A

T

A

T

A

= +85°C

= +25°C

= +85°C

50

Years

200,000

50,000

Endurance

Stores

POWER SUPPLIES

Single-Supply Voltage

V

= GND = 0

SS

2.70

2.50

-2.5

5.25

-0.2

V

DD

GND = 0

Dual-Supply Voltage

V

(V - V ) ≤ 5.25V

SS

DD

SS

During nonvolatile write only;

digital inputs = V or GND

Average Programming Current

I

220

400

ꢀA

PG

DD

During nonvolatile write only;

digital inputs = V or GND

Peak Programming Current

Standby Current

4

mA

ꢀA

DD

I

Digital inputs = V

or GND, T = +25°C

0.6

1.5

DD

A

4

_______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

TIMING CHARACTERISTICS

(V

= +2.7V to +5.25V, V = GND = 0, V = V , V = 0, T = -40°C to +85°C, unless otherwise noted. Typical values are at

DD

SS

H_

DD L_

A

V

DD

= +5.0V, T = +25°C.) (Note 1)

A

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

ANALOG SECTION

MAX5494/MAX5498

MAX5495/MAX5499

5

Wiper Settling Time (Note 6)

t

S

ꢀs

22

SPI-COMPATIBLE SERIAL INTERFACE (Figure 6)

SCLK Frequency

f

7

MHz

ns

SCLK

SCLK Clock Period

t

140

60

0

CP

CH

SCLK Pulse-Width High

SCLK Pulse-Width Low

CS Fall to SCLK Rise Setup

SCLK Rise to CS Rise Hold

DIN to SCLK Setup

t

ns

t

CL

t

ns

CSS

CSH

t

ns

t

40

0

DS

DH

DIN Hold After SCLK

t

ns

SCLK Rise to CS Fall Delay

CS Rise to SCLK Rise Hold

CS Pulse-Width High

t

15

60

150

CS0

CS1

t

ns

CSW

Write NV Register Busy Time

t

12

ms

BUSY

Note 1: 100% production tested at T = +25°C and T = +85°C. Guaranteed by design to T = -40°C.

A

Note 2: The DNL and INL are measured for the voltage-divider with H_ = V

and L_ = V . The wiper terminal (W_) is unloaded

DD

SS

and measured with a high-input-impedance voltmeter.

Note 3: The DNL and INL are measured with L_ = V = 0. For V

= 5V, the wiper terminal is driven with a current source of I

=

SS

DD

W

80ꢀA for the 50kΩ device and I = 400ꢀA for the 10kΩ device. For V

= 3V, the wiper terminal is driven with a current

W

DD

source of I = 40ꢀA for the 50kΩ device and I = 200ꢀA for the 10kΩ device.

W

Note 4: The wiper resistance is measured using the source currents given in Note 3.

Note 5: The device draws higher supply current when the digital inputs are driven with voltages between (V

- 0.5V) and (GND +

DD

0.5V). See the Supply Current vs. Digital Input Voltage graph in the Typical Operating Characteristics.

Note 6: Wiper settling test condition uses the voltage-divider with a 10pF load on W_. Transition code from 0 to 495 and measure

the time from CS going high to the wiper voltage settling to within 0.5% of its final value.

_______________________________________________________________________________________

5

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Typical Operating Characteristics

(V

= +5.0V, V = 0, T = +25°C, unless otherwise noted.)

SS A

DD

INTEGRAL NONLINEARITY

vs. CODE (VARIABLE RESISTOR)

MAXIMUM DIFFERENTIAL NONLINEARITY

vs. SUPPLY VOLTAGE (VARIABLE RESISTOR)

DIFFERENTIAL NONLINEARITY

vs. CODE (VARIABLE RESISTOR)

1.5

1.0

0.5

0

1.0

V

= 3V

V

= 3V

DD

0.8

0.6

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

-1.0

-0.2

-0.4

-0.6

-0.8

-1.0

-0.5

-1.0

-1.5

0

128 256 384 512 640 768 896 1024

CODE

2.5

3.0

3.5

4.0

(V)

4.5

5.0

0

128 256 384 512 640 768 896 1024

CODE

–MAX549

V

DD

MAXIMUM INTEGRAL NONLINEARITY

vs. SUPPLY VOLTAGE (VARIABLE RESISTOR)

INTEGRAL NONLINEARITY

vs. CODE (VOLTAGE-DIVIDER)

DIFFERENTIAL NONLINEARITY

vs. CODE (VOLTAGE-DIVIDER)

1.0

1.5

1.0

0.5

0

1.0

0.8

V

= 3V

V

= 3V

DD

0.5

0

0.6

0.4

0.2

-0.5

-1.0

-1.5

-2.0

0

-0.2

-0.4

-0.6

-0.8

-1.0

-0.5

-1.0

-1.5

2.5

3.0

3.5

4.0

(V)

4.5

5.0

0

128 256 384 512 640 768 896 1024

CODE

0

128 256 384 512 640 768 896 1024

CODE

V

DD

END-TO-END RESISTANCE

vs. CODE (MAX5497/MAX5499)

END-TO-END RESISTANCE vs. CODE

(MAX5496/MAX5498)

WIPER RESISTANCE vs. CODE

(VARIABLE RESISTOR)

60

12

10

8

80

70

60

50

40

30

20

10

0

50

40

30

20

10

0

6

4

2

0

128 256 384 512 640 768 896 1024

CODE

0

128 256 384 512 640 768 896 1024

CODE

0

128 256 384 512 640 768 896 1024

CODE

6

_______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

Typical Operating Characteristics (continued)

(V

= +5.0V, V = 0, T = +25°C, unless otherwise noted.)

SS A

DD

END-TO-END RESISTANCE (R

% CHANGE vs. TEMPERATURE

(VOLTAGE-DIVIDER)

)

HL

WIPER-TO-END RESISTANCE (R

)

WL

% CHANGE vs. TEMPERATURE

(VARIABLE RESISTOR)

WIPER RESISTANCE vs. WIPER VOLTAGE

(VARIABLE RESISTOR)

1.0

0.8

1.0

0.8

22

CODE IS 11 1111 1111

V

= 5V

CODE IS 00 0000 0000

DD

21

20

0.6

0.4

0.2

0

19

18

17

16

-0.2

-0.4

-0.6

-0.8

-1.0

-0.2

-0.4

-0.6

-0.8

-1.0

-40

-15

10

35

60

85

-40

-15

10

35

60

85

0

1

2

3

4

5

TEMPERATURE (°C)

WIPER VOLTAGE (V)

STANDBY SUPPLY CURRENT

vs. TEMPERATURE

RATIOMETRIC TEMPERATURE

COEFFICIENT vs. CODE

DIGITAL SUPPLY CURRENT

vs. DIGITAL INPUT VOLTAGE

1.5

200

180

160

140

120

100

80

10,000

1000

100

10

V

= 5.25V

VOLTAGE-DIVIDER

DD

V

= 5V

DD

V

= 3V

DD

T

= -40°C TO +85°C

A

1.2

0.9

0.6

0.3

0

60

40

1

10kΩ

50kΩ

20

0

0.1

-40

-15

10

35

60

85

0

128 256 384 512 640 768 896 1024

CODE

0

1

2

3

4

5

TEMPERATURE (°C)

DIGITAL INPUT VOLTAGE (V)

TAP-TO-TAP SWITCHING TRANSIENT

VARIABLE RESISTOR TEMPERATURE

COEFFICIENT vs. CODE

TAP-TO-TAP SWITCHING TRANSIENT

(MAX5494/MAX5498)

(MAX5495/MAX5499)

MAX5494 toc18

MAX5494 toc17

700

600

500

400

300

200

100

0

CS

2V/div

CS

2V/div

V

= 3V

DD

T

= -40°C TO +85°C

A

V

W_

20mV/div

H_ = V

L_ = GND

FROM CODE 01111 11111

TO CODE 10000 00000

H_ = V

DD

L_ = GND

FROM CODE 01111 11111

TO CODE 10000 00000

DD

50kΩ

10kΩ

C

= 10pF

C

W_

= 10pF

W_

0

128 256 384 512 640 768 896 1024

CODE

4µs/div

1µs/div

_______________________________________________________________________________________

7

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Typical Operating Characteristics (continued)

(V

= +5.0V, V = 0, T = +25°C, unless otherwise noted.)

SS A

DD

CROSSTALK

CROSSTALK vs. FREQUENCY

MAX5494 toc19

V

W2

0

C

= 10pF

2V/div

W_

CODE = 01111 01111

-20

-40

-60

V

W1

-80

20mV/div

MAX5494/MAX5498

MAX5495/MAX5499

V

C

= V

DD

H2

L2

-100

-120

= V = V = GND

L1

H1

= 10pF

W_

400ns/div

1000

0.01

0.1

1

10

100

FREQUENCY (kHz)

–MAX549

THD+N vs. FREQUENCY

(MAX5495/MAX5499)

THD+N vs. FREQUENCY

(MAX5494/MAX5498)

10

1

10

1

C

= 10pF

CODE = 01111 01111

W_

C

= 10pF

CODE = 01111 01111

W_

0.1

0.01

0.001

0.0001

0.001

0.0001

0.01

0.1

1

10

100

0.01

0.1

1

10

100

FREQUENCY (kHz)

WIPER RESPONSE vs. FREQUENCY

(MAX5494/MAX5498)

WIPER RESPONSE vs. FREQUENCY

(MAX5495/MAX5499)

0

-5

0

-5

C

= 10pF

W_

C

= 10pF

W_

-10

-15

-20

-25

-10

-15

-20

-25

C

= 30pF

W_

C

= 30pF

W_

CODE = 01111 01111

0.1

CODE = 01111 01111

0.1

1

10

FREQUENCY (kHz)

100

1000

1

10

FREQUENCY (kHz)

100

1000

8

_______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

Pin Descriptions

NAME

FUNCTION

MAX5494/ MAX5496/ MAX5498/

MAX5495 MAX5497 MAX5499

Active-Low Chip-Select Input. Drive CS low to enable the serial interface. Drive

CS high to disable the serial interface and put the device in standby mode.

1

CS

2

3

4

2

3

2

3

W2

L2

Wiper Terminal 2

Low Terminal 2

High Terminal 2

—

H2

Positive Power-Supply Input. 2.7V ≤ V ≤ 5.25V. Bypass with a 0.1ꢀF

DD

5

V

DD

capacitor from V

to GND as close to the device as possible

DD

6, 7,14,15 6, 7,14,15 6, 7,14,15

N.C.

No Connection. Not internally connected.

Negative Power-Supply Input.

Single-supply operation: V = GND = 0.

SS

Dual-supply operation: -2.5V ≤ V ≤ -0.2V (V can vary as long as

SS

8

V

SS

(V

DD

- V ) ≤ 5.25V).

SS

Bypass with a 0.1ꢀF capacitor from V to GND as close to the device

SS

as possible.

9

—

10

11

12

9

H1

L1

High Terminal 1

Low Terminal 1

Wiper Terminal 1

Ground

10

11

12

10

11

12

W1

GND

Serial-Data Input. The data at DIN synchronously loads into the serial shift

register on each SCLK rising edge.

13

DIN

16

—

16

4

SCLK

D.N.C

Serial-Clock Input . SCLK clocks in the data when CS is low.

4, 9

Do Not Connect. Leave unconnected for proper operation.

Eꢁposed Eꢁposed Pad. Eꢁternally connect EP to V to provide a low thermal resistance

SS

EP

Pad

path from the IC junction to the PC board or leave unconnected.

_______________________________________________________________________________________

9

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Functional Diagrams

H1

1024

TAPS

10

10-BIT

LATCH

V

DD

W1

DECODER

GND

2 x 10

BIT

NVM

V

SS

POR

CS

SCLK

DIN

SPI

INTERFACE

10

10-BIT

LATCH

–MAX549

L1

H2

1024

TAPS

MAX5494

MAX5495

W2

DECODER

L2

NOTE: THE PROGRAMMABLE VOLTAGE-DIVIDER IS NOT INTENDED FOR CURRENT TO FLOW THROUGH THE WIPER.

NOTE: SEE THE MAX5494/MAX5495/MAX5498/MAX5499 PROGRAMMABLE VOLTAGE-DIVIDERS SECTION.

Figure 1. MAX5494/MAX5495 Functional Diagram

10 ______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

Functional Diagrams (continued)

1024

TAPS

10

10-BIT

LATCH

V

DD

W1

L1

DECODER

GND

2 x 10

BIT

NVM

V

SS

POR

CS

SCLK

DIN

SPI

INTERFACE

1024

TAPS

10

10-BIT

LATCH

W2

L2

DECODER

MAX5496

MAX5497

Figure 2. MAX5496/MAX5497 Functional Diagram

H1

1024

TAPS

10

10-BIT

LATCH

V

DD

W1

DECODER

GND

2 x 10

BIT

NVM

V

SS

POR

CS

SCLK

DIN

SPI

INTERFACE

10

10-BIT

LATCH

L1

1024

TAPS

MAX5498

MAX5499

W2

L2

DECODER

NOTE: THE PROGRAMMABLE VOLTAGE-DIVIDER IS NOT INTENDED FOR CURRENT TO FLOW THROUGH THE WIPER.

NOTE: SEE THE MAX5494/MAX5495/MAX5498/MAX5499 PROGRAMMABLE VOLTAGE-DIVIDERS SECTION.

Figure 3. MAX5498/MAX5499 Functional Diagram

______________________________________________________________________________________ 11

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Detailed Description

⎡

⎤

|

ZSE

V

− |V

| + |V

(

)

+ V + |V

⎥

HL

FSE

D

|

ZSE

⎢

L

The MAX5494–MAX5499 dual, nonvolatile, linear-taper,

programmable voltage-dividers and variable resistors

feature 1024 tap points (10-bit resolution) (see the

Functional Diagrams). These devices consist of multi-

ple strings of equal resistor segments with a wiper con-

tact that moves among the 1024 effective tap points by

a 3-wire SPI-compatible serial interface. The

MAX5494/MAX5496/MAX5498 provide a total 10kΩ

end-to-end resistance, and the MAX5495/MAX5497/

MAX5499 feature a 50kΩ end-to-end resistance. The

MAX5494/MAX5495/MAX5498/MAX5499 allow access

to the high, low, and wiper terminals for a standard volt-

age-divider configuration. Ensure that the terminal volt-

1023

⎢

⎥

⎦

⎣

where D is the decimal equivalent of the 10 data bits

written (0 to 1023), V is the voltage difference between

HL

the H_ and L_ terminals, and:

V

1024

⎡

⎤

HL

V

= FSE

FSE

⎢

⎥

⎣

⎦

V

1024

⎡

⎤

HL

V

= ZSE

ZSE

⎢

⎥

⎣

⎦

The MAX5494/MAX5498 provide a 10kΩ end-to-end

resistance value, while the MAX5495/MAX5499 feature a

50kΩ end-to-end resistance value. Note that the pro-

grammable voltage-divider is not intended to be used

as a variable resistor. Wiper current creates a nonlinear

voltage drop in series with the wiper. To ensure tempera-

ture drift remains within specifications, do not pull current

through the voltage-divider wiper. Connect the wiper to a

high-impedance node. Figures 4 and 5 show the behav-

ior of the programmable voltage-divider resistance from

W_ to H_ and W_ to L_, respectively. This does not apply

to the variable-resistor devices.

ages fall between V and V

.

DD

SS

MAX5494/MAX5495/MAX5498/MAX5499

Programmable Voltage-Dividers

The MAX5494/MAX5495/MAX5498/MAX5499 program-

mable voltage-dividers provide a weighted average of

the voltage between the H_ and L_ inputs at the W_

output.

–MAX549

The MAX5494/MAX5495/MAX5498/MAX5499 program-

mable voltage-divider network provides up to 1024

division ratios between the H_ and L_ voltage. Ideally,

the V voltage occurs at the wiper terminal when all

L

data bits are zeros and the V voltage occurs at the

H

MAX5496–MAX5499 Variable Resistors

The MAX5496–MAX5499 provide a programmable resis-

tance from W_ to L_. The MAX5496/MAX5498 provide a

10kΩ end-to-end resistance value, while the

MAX5497/MAX5499 feature a 50kΩ end-to-end resis-

tance value. The programmable resolution of this

wiper terminal when all data bits are one (see the wiper

voltage equation). The step-size voltage (1 LSB) is

equal to the voltage applied across terminals H and L

divided by 2¹⁰. Calculate the wiper voltage V as fol-

W

lows:

18

16

14

12

10

8

18

16

14

12

10

8

6

4

2

0

128 256 384 512 640 768 896 1024

CODE (DECIMAL)

0

128 256 384 512 640 768 896 1024

CODE (DECIMAL)

50kΩ SCALES BY A FACTOR OF FIVE

Figure 5. Resistance from W_ to L_ vs. Code (10kΩ Voltage-

Divider)

Figure 4. Resistance from W_ to H_ vs. Code (10kΩ Voltage-

Divider)

12 ______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

resistance is equal to the nominal end-to-end resis-

either eight clock cycles to transfer the command bits

(Figure 7b) or 24 clock cycles with 16 bits disregarded

by the device (Figure 7a).

tance divided by 1024 (10-bit resolution). For eꢁample,

the programmable resolution is 9.8Ω and 48.8Ω for the

MAX5496/MAX5498 and the MAX5497/MAX5499,

respectively.

After the loading of data into the shift register, drive CS

high to latch the data into the appropriate control regis-

ter (specified by RA1 and RA0) and disable the serial

interface. Keep CS low during the entire serial data

stream to avoid corruption of the data. Table 2 shows

the register map.

The 10-bit data in the 10-bit latch register selects the

wiper position from the 1024 possible positions, result-

ing in 1024 values for the resistance from W_ to L_.

Calculate the resistance from W_ to L_ (R ) from the

WL

formula below:

Write Wiper Register

The “write wiper register” command (C1, C0 = 00) con-

trols the wiper positions. The 10 data bits (D9–D0) indi-

cate the position of the wiper. For eꢁample, if DIN =

000000 0000, the wiper moves to the position closest to

L_. If DIN = 11 1111 1111, the wiper moves closest to H_.

D

1023

R

D =

( )

×R

+R

W−L Z

WL

where D is decimal equivalent of the 10 data bits writ-

ten, R is the nominal end-to-end resistance, and R

W-L

Z

is the zero-scale error. Table 1 shows R

codes.

at selected

WL

Table 1. R_WLat Selected Codes

SPI-Compatible Serial Interface

The MAX5494–MAX5499 use a 3-wire, SPI-compatible,

serial data interface (Figure 6). This write-only interface

contains three inputs: chip-select (CS), data input

(DIN), and data clock (SCLK). Drive CS low to enable

the serial interface and clock data synchronously into

the shift register on each SCLK rising edge.

END-TO-END RESISTANCE VALUE

CODE (DECIMAL)

10kΩ

(Ω)

50kΩ

R (Ω)

WL

R

WL

0

1

70

110

160

80

512

1023

5,070

10,070

25,110

50,110

The WRITE commands (C1, C0 = 00 or 01) require 24

clock cycles to transfer the command and data (Figure

7a). The COPY commands (C1, C0 = 10 or 11) use

CS

t

CSW

t

CSS

t

CS1

t

CP

t

CL

CH

CSH

CSO

SCLK

DIN

t

DH

DS

Figure 6. SPI-Interface Timing Diagram

______________________________________________________________________________________ 13

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

a) 24-BIT COMMAND/DATA WORD

CS

SCLK

11 12

RA1 RA0 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

23 24

1

2

3

4

5

6

7

8

9

13 14 15 16

18 19 20 21 22

10

17

C1 C0

DIN

b) 8-BIT COMMAND WORD

CS

SCLK

1

2

3

4

5

6

7

8

DIN

C1 C0

RA1 RA0

–MAX549

Figure 7. SPI-Compatible Serial-Interface Format

Table 2. Register Map*

CLOCK EDGE

Bit Name

1

—

0

2

—

0

3

4

5

—

0

6

—

0

7

8

9

10 11 12 13 14 15 16 17 18

…

—

24

—

C1 C0

RA1 RA0 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Write Wiper Register 1

Write Wiper Register 2

Write NV Register 1

Write NV Register 2

0

1

0

1

0

1

0

1

0

D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

0

Copy Wiper Register 1

to NV Register 1

0

1

0

1

0

—

Copy Wiper Register 2

to NV Register 2

Copy Wiper Register 1

to NV Register 1 and

Copy Wiper Register 2

to NV Register 2

0

1

0

1

—

Simultaneously

Copy NV Register 1 to

Wiper Register 1

0

1

0

1

0

—

Copy NV Register 2 to

Wiper Register 2

Copy NV Register 1 to

Wiper Register 1 and

Copy NV Register 2 to

Wiper Register 2

0

1

0

1

—

Simultaneously

*D9 is the MSB and D0 is the LSB of the data bits.

14 ______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

The “write wiper register” command writes data to the

the NV register does not affect the position of the

wipers. The operation takes up to 12ms (maꢁ) after CS

goes high to complete and no other operation should

be performed until completion. Figure 9 shows how to

write data to the NV register 1.

volatile random access memory (RAM), leaving the NV

registers unchanged. When the device powers up, the

data stored in the NV registers transfers to the wiper

register, moving the wiper to the stored position. Figure

8 shows how to write data to wiper register 1.

Copy Wiper Register to NV Register

The “copy wiper register to NV register” command (C1,

C0 = 10) stores the current position of the wiper to the

NV register for use at power-up. Figure 10 shows how

to copy data from wiper register 1 to NV register 1.

Write NV Register

The “write NV register” command (C1, C0 = 01) stores

the position of the wiper to the NV registers for use at

power-up. Alternatively, the “copy wiper register to NV

register” command writes to the NV register. Writing to

CS

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16

17 18 19 20 21 22 23 24

SCLK

DIN

C1 C0

RA1 RA0

0

1

D9 D8 D7 D6 D5 D4 D3 D2

D1 D0

X

WIPER

REGISTER 1

UPDATED

ACTION

Figure 8. Write Wiper Register 1

CS

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 16

17 18 19 20 21 22 23 24

SCLK

DIN

C1 C0

RA1 RA0

0

1

0

1

D9 D8 D7 D6 D5 D4 D3 D2

D1 D0

X

t

BUSY

WRITE NV

REGISTER 1

(DEVICE IS BUSY)

ACTION

Figure 9. Write NV Register 1

______________________________________________________________________________________ 15

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Copy NV Register to Wiper Register

The “copy NV register to wiper register” (C1, C0 = 11)

restores the wiper position to the current value stored in

the NV register. Figure 11 shows how to copy data from

NV register 1 to wiper register 1.

the factory. The nonvolatile memory is guaranteed for

50 years for wiper data retention and up to 200,000

wiper write cycles.

Power-Up

Upon power-up, the MAX5494–MAX5499 load the data

stored in the nonvolatile wiper register into the wiper

register, updating the wiper position with the data

stored in the nonvolatile wiper register.

Standby Mode

The MAX5494–MAX5499 feature a low-power standby

mode. When the device is not being programmed, it

enters into standby mode and supply current drops to

0.6ꢀA (typ).

Applications Information

The MAX5494–MAX5499 are intended for circuits

requiring digitally controlled adjustable resistance,

such as LCD contrast control (where voltage biasing

adjusts the display contrast), or programmable filters

with adjustable gain and/or cutoff frequency.

Nonvolatile Memory

The internal EEPROM consists of a nonvolatile register

that retains the last value stored prior to power-down.

The nonvolatile register is programmed to midscale at

–MAX549

CS

1

2

3

4

5

6

7

8

1

2

3

4

5

6

7

8

SCLK

DIN

SCLK

DIN

C1

C0

RA1 RA0

C1

C0

RA1 RA0

0

1

0

1

0

1

0

1

t

BUSY

WRITE NV

REGISTER 1

(DEVICE IS BUSY)

WIPER REGISTER

1 UPDATED

ACTION

Figure 10. Copy Wiper Register 1 to NV Register 1

Figure 11. Copy NV Register 1 to Wiper Register 1

16 ______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

Positive LCD Bias Control

R1

R2

1

G =1+

Figures 12 and 13 show an application where the volt-

age-divider or variable resistor is used to make an

adjustable, positive LCD-bias voltage. The op amp pro-

vides buffering and gain to the resistor-divider network.

f

=

C

2π × R3 × C

Programmable Filter

Figure 14 shows the configuration for a 1st-order pro-

grammable filter. The gain of the filter is adjusted by

R2, and the cutoff frequency is adjusted by R3. Use the

following equations to calculate the gain (G) and the

Gain and Offset Voltage Adjustment

Figure 15 shows an application using the MAX5498/

MAX5499 to adjust the gain and nullify the offset voltage.

3dB cutoff frequency (f ).

C

5V

H_

30V

1/2 MAX5494/MAX5495

1/2 MAX5498/MAX5499

W_

V

OUT

V

OUT

MAX480

L_

1/2 MAX5496–MAX5499

W_

L_

Figure 13. Positive LCD Bias Control Using a Variable Resistor

Figure 12. Positive LCD Bias Control Using a Voltage-Divider

C

V

REF

V

IN

H_

V

OUT

1/2 MAX5498/MAX5499

R3

1/2 MAX5496–MAX5499

W_

V

OUT

W_

R1

L_

1/2 MAX5498/MAX5499

1/2 MAX5496–MAX5499

R2

W_

L_

V

IN

Figure 14. Programmable Filter

Figure 15. Gain- and Offset-Voltage Adjustment Circuit

______________________________________________________________________________________ 17

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Selector Guide

Ordering Information (continued)

PIN-

PACKAGE

END-TO-END

RESISTANCE

PART

TEMP RANGE

PKG CODE

PART

CONFIGURATION

(kΩ)

MAX5496ETE -40°C to +85°C 16 TQFN-EP*

MAX5497ETE -40°C to +85°C 16 TQFN-EP*

MAX5498ETE -40°C to +85°C 16 TQFN-EP*

MAX5499ETE -40°C to +85°C 16 TQFN-EP*

T1655-2

Two programmable voltage-

dividers

MAX5494ETE

MAX5495ETE

10

50

Two programmable voltage-

dividers

*EP = Eꢁposed pad.

MAX5496ETE Two variable resistors

MAX5497ETE Two variable resistors

10

50

One programmable voltage-

MAX5498ETE

10

50

divider and one variable resistor

Chip Information

TRANSISTOR COUNT: 32,262

One programmable voltage-

MAX5499ETE

divider and one variable resistor

PROCESS: BiCMOS

–MAX549

Pin Configurations (continued)

TOP VIEW

12

11

10

9

DIN 13

V

SS

8

7

6

5

N.C.

14

15

N.C.

MAX5498

MAX5499

SCLK 16

V

DD

1

2

3

4

5mm × 5mm × 0.8mm TQFN

18 ______________________________________________________________________________________

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

–MAX549

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information

go to www.maxim-ic.com/packages.)

______________________________________________________________________________________ 19

10-Bit, Dual, Nonvolatile, Linear-Taper

Digital Potentiometers

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information

go to www.maxim-ic.com/packages.)

–MAX549

Maꢁim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maꢁim product. No circuit patent licenses are

implied. Maꢁim reserves the right to change the circuitry and specifications without notice at any time.

20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

is a registered trademark of Maꢁim Integrated Products, Inc.


型号：	MAX5494
厂家：	MAXIM INTEGRATED PRODUCTS
描述：	10-Bit, Dual, Nonvolatile, Linear-Taper Digital Potentiometers 10位，双路，非易失，线性变化数字电位器电位器
文件：	总20页 (文件大小：682K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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