REV. D

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a

Complete 14-Bit, Sampling ADCs

AD7871/AD7872

FEATURES

Complete Monolithic 14-Bit ADC

2s Complement Coding

Parallel, Byte and Serial Digital Interface

80 dB SNR at 10 kHz Input Frequency

57 ns Data Access Time

Low Power—50 mW typ

83 kSPS Throughput Rate

16-Lead SOIC (AD7872)

APPLICATIONS

Digital Signal Processing

High Speed Modems

Speech Recognition and Synthesis

Spectrum Analysis

DSP Servo Control

GENERAL DESCRIPTION

The AD7871 and AD7872 are fast, complete, 14-bit analog-to-

digital converters. They consist of a track/hold amplifier,

successive-approximation ADC, 3 V buried Zener reference and

versatile interface logic. The ADC features a self-contained, laser

trimmed internal clock, so no external clock timing components

are required. The on-chip clock may be overridden to synchronize

ADC operation to the digital system for minimum noise.

The AD7871 offers a choice of three data output formats: a sin-

gle, parallel, 14-bit word; two 8-bit bytes or a 14-bit serial data

stream. The AD7872 is a serial output device only. The two

parts are capable of interfacing to all modern microprocessors

and digital signal processors.

The AD7871 and AD7872 operate from

±5 V power supplies,

accept bipolar input signals of

±3 V and can convert full power

signals up to 41.5 kHz.

In addition to the traditional dc accuracy specifications, the

AD7871 and AD7872 are also fully specified for dynamic perfor-

mance parameters including distortion and signal-to-noise ratio.

Both devices are fabricated in Analog Devices’ LC

technology process. The AD7871 is available in 28-pin plastic DIP

and PLCC packages. The AD7872 is available in a 16-pin plastic

DIP, hermetic DIP and 16-lead SOIC packages.

FUNCTIONAL BLOCK DIAGRAMS

PRODUCT HIGHLIGHTS

1. Complete 14-Bit ADC on a Chip.

2. Dynamic Specifications for DSP Users.

3. Low Power.

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., 1997