REV. A

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a

CMOS Dual 8-Bit

Buffered Multiplying DAC

AD7628

FUNCTIONAL BLOCK DIAGRAM

GENERAL DESCRIPTION

The AD7628 is a monolithic dual 8-bit digital/analog converter

featuring excellent DAC-to-DAC matching. It is available in

small 0.3" wide 20-pin DIPs and in 20-terminal surface mount

packages.

Separate on-chip latches are provided for each DAC to allow

easy microprocessor interface.

Data is transferred into either of the two DAC data latches via a

common 8-bit TTL/CMOS compatible input port. Control in-

put

DAC A/DAC B determines which DAC is to be loaded.

The AD7628’s load cycle is similar to the write cycle of a ran-

dom access memory, and the device is bus compatible with most

8-bit microprocessors, including 6502, 6809, 8085, Z80.

The device operates from a +12 V to +15 V power supply and is

TTL-compatible over this range. Power dissipation is a low

20 mW.

Both DACs offer excellent four quadrant multiplication charac-

teristics with a separate reference input and feedback resistor for

each DAC.

PRODUCT HIGHLIGHTS

1. DAC to DAC matching: since both of the AD7628 DACs

are fabricated at the same time on the same chip, precise

matching and tracking between DAC A and DAC B is inher-

ent. The AD7628’s matched CMOS DACs make a whole

new range of applications circuits possible, particularly in the

audio, graphics and process control areas.

2. Small package size: combining the inputs to the on-chip

DAC latches into a common data bus and adding a

DAC A/

DAC B select line has allowed the AD7628 to be packaged in

a small 20-pin 0.3" wide DIP, 20-pin SOIC, 20-terminal

PLCC and 20-terminal LCC.

3. TTL-Compatibility: All digital inputs are TTL-compatible

over a +12 V to +15 V power supply range.

FEATURES

On-Chip Latches for Both DACs

+12 V to +15 V Operation

DACs Matched to 1%

Four Quadrant Multiplication

TTL/CMOS Compatible from +12 V to +15 V

Latch Free (Protection Schottkys not Required)

APPLICATIONS

Disk Drives

Programmable Filters

X-Y Graphics

Gain/Attenuation

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

Tel: 617/329-4700

World Wide Web Site: http://www.analog.com

Fax: 617/326-8703

© Analog Devices, Inc., 1996