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a

AD5232

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

Tel: 781/329-4700

www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2001

*

8-Bit Dual Nonvolatile Memory

Digital Potentiometer

FEATURES

Nonvolatile Memory Preset Maintains Wiper Settings

Dual Channel, 256-Position Resolution

Full Monotonic Operation DNL < 1 LSB

10 k , 50 k , 100 k

Terminal Resistance

Linear or Log Taper Settings

Push-Button Increment/Decrement Compatible

SPI-Compatible Serial Data Input with Readback

Function

3 V to 5 V Single Supply or

2.5 V Dual Supply

Operation

14 Bytes of User EEMEM Nonvolatile Memory for

Constant Storage

Permanent Memory Write Protection

APPLICATIONS

Mechanical Potentiometer Replacement

Instrumentation: Gain, Offset Adjustment

Programmable Voltage-to-Current Conversion

Programmable Filters, Delays, Time Constants

Line Impedance Matching

Power Supply Adjustment

DIP Switch Setting

GENERAL DESCRIPTION

The AD5232 device provides a nonvolatile, dual-channel,

digitally controlled variable resistor (VR) with 256-position

resolution. These devices perform the same electronic adjust-

ment function as a potentiometer or variable resistor. The

AD5232’s versatile programming via a microcontroller allows

multiple modes of operation and adjustment.

In the direct program mode a predetermined setting of the RDAC

register can be loaded directly from the microcontroller.

Another key mode of operation allows the RDAC register to be

refreshed with the setting previously stored in the EEMEM

register. When changes are made to the RDAC register to estab-

lish a new wiper position, the value of the setting can be saved

into the EEMEM by executing an EEMEM save operation.

Once the settings are saved in the EEMEM register these values

will be automatically transferred to the RDAC register to set the

wiper position at system power ON. Such operation is enabled

by the internal preset strobe and the preset can also be accessed

externally.

All internal register contents can be read out of the serial data

output (SDO). This includes the RDAC1 and RDAC2 registers,

the corresponding nonvolatile EEMEM1 and EEMEM2 regis-

ters, and the 14 spare USER EEMEM registers available for

constant storage.

*Patent pending.

FUNCTIONAL BLOCK DIAGRAM

RDAC1

REGISTER

EEMEM1

RDAC2

REGISTER

EEMEM

CONTROL

14 BYTES

USER EEMEM

EEMEM2

AD5232

RDAC1

RDAC2

CS

CLK

WP

PR

SDI

GND

SDO

RDY

SDO

SERIAL

INTERFACE

ADDR

DECODE

A1

W1

B1

A2

W2

B2

SDI

The basic mode of adjustment is the increment and decrement

command controlling the present setting of the Wiper position

setting (RDAC) register. An internal scratch pad RDAC register

can be moved UP or DOWN one step of the nominal terminal

resistance between terminals A and B. This linearly changes the

rithmic changes in wiper setting, a left/right shift command

adjusts levels in

±6 dB steps, which can be useful for audio and

light alarm applications.

The AD5232 is available in a thin TSSOP-16 package. All parts

are guaranteed to operate over the extended industrial tempera-

ture range of –40

°C to +85°C. An evaluation board is available,

Part Number: AD5232EVAL.

CODE – Decimal

100

75

0

0

256

64

128

192

50

25

Figure 1. Symmetrical RDAC Operation