1

DO

PROG

RDY/BSY

CLK

1

2

3

4

5

6

7

14

13

12

11

8

10

9

VDD

VREF H1

GND

VOUT1

CS

DI

VREF L1

NC

NC

NC

DO

PROG

RDY/BSY

CLK

1

2

3

4

5

6

7

14

13

12

11

8

10

9

VDD

VREF H1

GND

VOUT1

CS

DI

VREF L1

NC

NC

NC

CAT521

8-Bit Digital POT With Independent Reference Inputs

FEATURES

APPLICATIONS

Calibrating and Adaptive Control systems.

DESCRIPTION

The CAT521 is a dual 8-Bit Memory DAC designed as an

electronic replacement for mechanical potentiometers

and trim pots. Intended for final calibration of products

such as camcorders, fax machines and cellular tele-

phones on automated high volume production lines and

systems capable of self calibration, it is also well suited

for applications were equipment requiring periodic ad-

justment is either difficult to access or located in a

hazardous environment.

The CAT521 consists of a programmable DAC with

independent high and low reference inputs and is ca-

pable of a rail to rail output swing. The output is buffered

by a rail to rail OP AMP. Output settings, stored in non-

volatile EEPROM memory, are not lost when the device

is powered down and are automatically reinstated when

power is returned. The output can be dithered to test

new output values without effecting the stored settings

FUNCTIONAL DIAGRAM

PIN CONFIGURATION

and stored settings can be read back without disturbing

the DAC’s output.

Control of the CAT521 is accomplished with a simple 3

wire serial interface. A Chip Select pin allows several

CAT521's to share a common serial interface and com-

munications back to the host controller is via a single

serial data line thanks to the CAT521’s Tri-Stated Data

Output pin. A RDY/

BSY output working in concert with

an internal low voltage detector signals proper operation

of EEPROM Erase/Write cycle.

The CAT521 operates from a single 3–5 volt power

supply. The high voltage required for EEPROM Erase/

Write operations is generated on-chip.

The CAT521 is available in the 0

°C to 70°C Commercial

and –40

°C to +85°C Industrial operating temperature

ranges and offered in 14-pin plastic DIP and Surface

mount packages.

DIP Package (P)

SOIC Package (J)

CAT521

© 2001 by Catalyst Semiconductor, Inc.

Characteristics subject to change without notice

Advanced Information

CAT521

CAT521

GND

EEPROM

LATCH

DAC 1

12

PROG

RDY/

BSY

PROGRAM

CONTROL

H.V.

CHARGE

PUMP

SERIAL DATA OUTPUT

V

1

OUT

V

L1

REF

V

H1

REF

DO

DATA

CONTROLLER

14

3

CLK

CS

2

4

5

7

9

8

1

6

DI

+

–