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General Description

The MAX5477/MAX5478/MAX5479 nonvolatile, dual,
linear-taper, digital potentiometers perform the function
of a mechanical potentiometer, but replace the
mechanics with a simple 2-wire digital interface. Each
device performs the same function as a discrete poten-
tiometer or variable resistor and has 256 tap points.

The devices feature an internal, nonvolatile EEPROM
used to store the wiper position for initialization during
power-up. A write-protect feature prevents accidental
overwrites of the EEPROM. The fast-mode I

C-compati-

ble serial interface allows communication at data rates
up to 400kbps, minimizing board space and reducing
interconnection complexity in many applications. Three
address inputs allow a total of eight unique address
combinations.

The MAX5477/MAX5478/MAX5479 provide three nomi-
nal resistance values: 10k

(MAX5477), 50k

(MAX5478), or 100k

(MAX5479). The nominal resistor

temperature coefficient is 35ppm/°C end-to-end and
5ppm/°C ratiometric. The low temperature coefficient
makes the devices ideal for applications requiring a low-
temperature-coefficient variable resistor, such as low-
drift, programmable gain-amplifier circuit configurations.

The MAX5477/MAX5478/MAX5479 are available in 16-
pin 3mm x 3mm x 0.8mm thin QFN and 14-pin 4.4mm x
5mm TSSOP packages. These devices operate over
the extended -40°C to +85°C temperature range.

Applications

Mechanical Potentiometer Replacement

Low-Drift Programmable-Gain Amplifiers

Volume Control

Liquid-Crystal Display (LCD) Contrast Control

Features

Power-On Recall of Wiper Position from

Nonvolatile Memory

EEPROM Write Protection
Tiny 3mm x 3mm x 0.8mm Thin QFN Package
35ppm/°C End-to-End Resistance Temperature

Coefficient

5ppm/°C Ratiometric Temperature Coefficient
Fast 400kbps I

-Compatible Serial Interface

1µA (max) Static Supply Current
Single-Supply Operation: +2.7V to +5.25V
256 Tap Positions per Potentiometer
±0.5 LSB DNL in Voltage-Divider Mode
±1 LSB INL in Voltage-Divider Mode

MAX5477/MAX5478/MAX5479

Dual, 256-Tap, Nonvolatile, I

C-Interface,

Digital Potentiometers

________________________________________________________________ Maxim Integrated Products

MAX5477
MAX5478
MAX5479

8-BIT

SHIFT

POR

16-BIT
LATCH

16-BIT

MEMORY

SDA

SCL

256

POSITION
DECODER

256

POSITION
DECODER

256

GND

INTERFACE

Ordering Information/Selector Guide

Functional Diagram

19-3379; Rev 2; 12/04

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.

Pin Configurations appear at end of data sheet.

Purchase of I

C components from Maxim Integrated

Products, Inc. or one of its sublicensed Associated
Companies, conveys a license under the Philips I

C Patent

Rights to use these components in an I

C system, provided

that the system conforms to the I

C Standard Specification as

defined by Philips.

PART

TEMP RANGE

PIN-PACKAGE

END-TO-END

RESISTANCE (k

)

TOP

MARK

PACKAGE CODE

MAX5477ETE*

-40°C to +85°C

16 Thin QFN

ABO

T1633F-3

MAX5477EUD*

-40°C to +85°C

14 TSSOP

MAX5478ETE*

-40°C to +85°C

16 Thin QFN

ABP

T1633F-3

MAX5478EUD

-40°C to +85°C

14 TSSOP

MAX5479ETE*

-40°C to +85°C

16 Thin QFN

100

ABQ

T1633F-3

MAX5479EUD

-40°C to +85°C

14 TSSOP

100

*Future product--contact factory for availability.

MAX5477/MAX5478/MAX5479

Dual, 256-Tap, Nonvolatile, I

C-Interface,

Digital Potentiometers

_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

= +2.7V to +5.25V, H_ = V

, L_ = GND, T

= -40°C to +85°C, unless otherwise noted. Typical values are at V

= +5V, T

+25°C.) (Note 1)

Stresses beyond those listed under "Absolute Maximum 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. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.

SDA, SCL, V

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

All Other Pins to GND.................................-0.3V to (V

+ 0.3V)

Maximum Continuous Current into H_, L_, and W_

MAX5477......................................................................

±5.0mA

MAX5478......................................................................

±1.3mA

MAX5479......................................................................

±0.6mA

Continuous Power Dissipation (T

= +70°C)

16-Pin Thin QFN (derate 17.5mW/°C above +70°C) 1399mW
14-Pin TSSOP (derate 9.1mW/°C above +70°C) .........727mW

Operating Temperature Range ...........................-40°C to +85°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

DC PERFORMANCE (VOLTAGE-DIVIDER MODE)

Resolution

256

Taps

Integral Nonlinearity

INL

(Note 2)

±1

LSB

Differential Nonlinearity

DNL

(Note 2)

±0.5

LSB

Dual Code Matching

R0 and R1 set to same code (all codes)

±1

LSB

End-to-End Resistance
Temperature Coefficient

ppm/°C

Ratiometric Resistance
Temperature Coefficient

ppm/°C

MAX5477

-3

MAX5478

-0.6

Full-Scale Error

MAX5479

-0.3

LSB

MAX5477

MAX5478

0.6

Zero-Scale Error

MAX5479

0.3

LSB

DC PERFORMANCE (VARIABLE-RESISTOR MODE)

= 3V

±3

Integral Nonlinearity (Note 3)

INL

= 5V

±1.5

LSB

= 3V, MAX5477, guaranteed

monotonic

±1

= 3V, MAX5478

±1

= 3V, MAX5479

±1

Differential Nonlinearity (Note 3)

DNL

= 5V

±1

LSB

Dual Code Matching

R0 and R1 set to same code
(all codes), V

= 3V or 5V

±3

LSB

DC PERFORMANCE (RESISTOR CHARACTERISTICS)

Wiper Resistance

(Note 4)

325

675

Wiper Capacitance

MAX5477

7.5

12.5

MAX5478

37.5

62.5

End-to-End Resistance

MAX5479

100

125

MAX5477/MAX5478/MAX5479

Dual, 256-Tap, Nonvolatile, I

C-Interface,

Digital Potentiometers

_______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

= +2.7V to +5.25V, H_ = V

, L_ = GND, T

= -40°C to +85°C, unless otherwise noted. Typical values are at V

= +5V, T

+25°C.) (Note 1)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

DIGITAL INPUTS

= 3.4V to 5.25V

2.4

Input High Voltage (Note 5)

< 3.4V

0.7 x V

Input Low Voltage

(Note 5)

0.8

Output Low Voltage

SINK

= 3mA

0.4

WP Pullup Resistance

255

Input Leakage Current

LEAK

±1

µA

Input Capacitance

DYNAMIC CHARACTERISTICS

Crosstalk

HA = 1kHz (0 to V

), LA = GND,

LB = GND, measure WB

-80

MAX5478

100

3dB Bandwidth (Note 6)

MAX5479

kHz

Total Harmonic Distortion Plus
Noise

THD+N

H_ = 1V

RMS

, f = 1kHz, L_ = GND,

measure W_

0.003

NONVOLATILE MEMORY RELIABILITY

Data Retention

= +85°C

Years

= +25°C

200,000

Endurance

= +85°C

50,000

Stores

POWER SUPPLY

Power-Supply Voltage

2.70

5.25

Writing to EEPROM, digital inputs at
GND or V

(Note 7)

250

400

WP = GND

20.6

Supply Current

Normal operation, digital
inputs at GND or V

WP = V

0.5

µA

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

ANALOG SECTION

MAX5478

500

Wiper Settling Time (Note 10)

MAX5479

1000

DIGITAL SECTION

SCL Clock Frequency

SCL

400

kHz

Setup Time for START Condition

SU:STA

0.6

µs

Hold Time for START Condition

HD:STA

0.6

µs

TIMING CHARACTERISTICS

= +2.7V to +5.25V, H_ = V

, L_ = GND, T

= -40°C to +85°C, unless otherwise noted. Typical values are at V

= +5V,

= +25°C. See Figure 1.) (Notes 8 and 9)

MAX5477/MAX5478/MAX5479

Dual, 256-Tap, Nonvolatile, I

C-Interface,

Digital Potentiometers

_______________________________________________________________________________________

Note 1:

All devices are production tested at T

= +25°C and are guaranteed by design and characterization for -40°C < T

< +85°C.

Note 2:

The DNL and INL are measured with the potentiometer configured as a voltage-divider with H_ = V

and L_ = GND. The

wiper terminal is unloaded and measured with a high-input-impedance voltmeter.

Note 3:

The DNL and INL are measured with the potentiometer configured as a variable resistor. H_ is unconnected and L_ =
GND. For V

= +5V, the wiper is driven with 400µA (MAX5477), 80µA (MAX5478), or 40µA (MAX5479). For V

= +3V,

the wiper is driven with 200µA (MAX5477), 40µA (MAX5478), or 20µA (MAX5479).

Note 4:

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

Note 5:

The devices draw current in excess of the specified supply current when the digital inputs are driven with voltages between
(V

- 0.5V) and (GND + 0.5V). See Supply Current vs. Digital Input Voltage in the Typical Operating Characteristics.

Note 6:

Wiper at midscale with a 10pF load (DC measurement). L_ = GND, an AC source is applied to H_, and the W_ output is
measured. A 3dB bandwidth occurs when the AC W_/H_ value is 3dB lower than the DC W_/H_ value.

Note 7:

The programming current exists only during power-up and EEPROM writes.

Note 8:

The SCL clock period includes rise and fall times (t

= t

). All digital input signals are specified with t

= t

= 2ns and

timed from a voltage level of (V

+ V

) / 2.

Note 9:

Digital timing is guaranteed by design and characterization, and is not production tested.

Note 10: This is measured from the STOP pulse to the time it takes the output to reach 50% of the output step size (divider mode). It

is measured with a maximum external capacitive load of 10pF.

Note 11: An appropriate bus pullup resistance must be selected depending on board capacitance. Refer to the I

C-bus specifica-

tion document linked to this web address: www.semiconductors.philips.com/acrobat/literature/9398/39340011.pdf

Note 12: The idle time begins from the initiation of the STOP pulse.

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

SCL High Time

HIGH

0.6

µs

SCL Low Time

LOW

1.3

µs

Data Setup Time

SU:DAT

100

Data Hold Time

HD:DAT

0.9

µs

SDA, SCL Rise Time

300

SDA, SCL Fall Time

300

Setup Time for STOP Condition

SU:STO

0.6

µs

Bus Free Time Between STOP
and START Condition

BUF

Minimum power-up rate = 0.2V/µs

1.3

µs

Pulse Width of Spike Suppressed

Capacitive Load for Each Bus
Line

(Note 11)

400

Write NV Register Busy Time

(Note 12)

TIMING CHARACTERISTICS (continued)

= +2.7V to +5.25V, H_ = V

, L_ = GND, T

= -40°C to +85°C, unless otherwise noted. Typical values are at V

= +5V,

= +25°C. See Figure 1.) (Notes 8 and 9)

MAX5477/MAX5478/MAX5479

Dual, 256-Tap, Nonvolatile, I

C-Interface,

Digital Potentiometers

_______________________________________________________________________________________

SUPPLY CURRENT

vs. TEMPERATURE

MAX5477/78/79 toc01

TEMPERATURE (

°C)

SUPPLY CURRENT (

-15

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

-40

= 5V

= 3V

100

200

150

300

250

350

450

400

500

128 160 192 224 256

WIPER RESISTANCE

vs. INPUT CODE

MAX5477/78/79 toc02

INPUT CODE

WIPER RESISTANCE (

)

TAP-TO-TAP SWITCHING TRANSIENT

MAX5477/78/79 toc03

µs/div

SDA
2V/div

W_
20mV/div

MAX5478
C

= 10pF

H_ = V

FROM TAP 00 TO TAP 04

TAP-TO-TAP SWITCHING TRANSIENT

MAX5477/78/79 toc04

400ns/div

SDA
2V/div

W_
20mV/div

MAX5479
C

= 10pF

H_ = V

FROM TAP 00 TO TAP 04

WIPER TRANSIENT AT POWER-ON

MAX5477/78/79 toc05

µs/div

2V/div

W_
1V/div

MAX5478
TAP = 128

WIPER TRANSIENT AT POWER-ON

MAX5477/78/79 toc06

µs/div

2V/div

W_
1V/div

MAX5479
TAP = 128

-0.3

-0.2

-0.1

0.1

0.2

0.3

128 160 192 224 256

INTEGRAL NONLINEARITY

vs. CODE (VDM MODE)

MAX5477/78/79 toc07

CODE

INL (LSB)

MAX5478

-0.3

-0.2

-0.1

0.1

0.2

0.3

128 160 192 224 256

DIFFERENTIAL NONLINEARITY

vs. CODE (VDM MODE)

MAX5477/78/79 toc08

CODE

DNL (LSB)

MAX5478

-0.3

-0.2

-0.1

0.1

0.2

0.3

128 160 192 224 256

INTEGRAL NONLINEARITY

vs. CODE (VRM MODE)

MAX5477/78/79 toc09

CODE

INL (LSB)

MAX5478

Typical Operating Characteristics

= +5V, H_ = V

, L_ = GND, T

= +25°C, unless otherwise noted.)

Part Number MAX5479