2
LC MOS
a
Complete 14-Bit, Sampling ADCs
AD7871/AD7872
FEATURES
FUNCTIO NAL BLO CK D IAGRAMS
Com plete Monolithic 14-Bit ADC
2s Com plem ent Coding
Parallel, Byte and Serial Digital Interface
80 dB SNR at 10 kHz Input Frequency
57 ns Data Access Tim e
Low Pow er—50 m W typ
83 kSPS Throughput Rate
16-Lead SOIC (AD7872)
APPLICATIONS
Digital Signal Processing
High Speed Modem s
Speech Recognition and Synthesis
Spectrum Analysis
DSP Servo Control
GENERAL D ESCRIP TIO N
T he AD7871 and AD7872 are fast, complete, 14-bit analog-to-
digital converters. T hey 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.
T he 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. T he AD7872 is a serial output device only. T he two
parts are capable of interfacing to all modern microprocessors
and digital signal processors.
T he 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’ LC2MOS mixed
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.
P RO D UCT H IGH LIGH TS
1. Complete 14-Bit ADC on a Chip.
2. Dynamic Specifications for DSP Users.
3. Low Power.
REV. D
Inform ation furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assum ed by Analog Devices for its
use, nor for any infringem ents of patents or other rights of third parties
which m ay result from its use. No license is granted by im plication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norw ood, MA 02062-9106, U.S.A.
Tel: 617/ 329-4700
Fax: 617/ 326-8703
World Wide Web Site: http:/ / w w w .analog.com
© Analog Devices, Inc., 1997