AD7871 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 single, 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 performance parameters including distortion and signal-to-noise ratio.
Both devices are fabricated in Analog Devices' LC2 MOS 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.
AD7871 Maximum Ratings
VDDto AGND . . . . . . . . . . . . . . . . . . . . . . . . 0.3 V to +7 V
VSSto AGND . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V to 7 V
AGND to DGND . . . . . . . . . . . . . . . . 0.3 V to VDD + 0.3 V
VINto AGND . . . . . . . . . . . . . . . . VSS0.3 V to VDD+ 0.3 V
REF OUT, CREFto AGND . . . . . . . . . . . . . . . . . . 0 V to VDD
Digital Inputs to DGND . . . . . . . . . . 0.3 V to VDD+ 0.3 V
Digital Outputs to DGND . . . . . . . . .0.3 V to VDD+ 0.3 V
Operating Temperature Range
Commercial (J, K Versions) . . . . . . . . . . . . . .0°C to +70°C
Industrial (A, B Versions) . . . . . . . . . . . . .40°C to +85°C
Extended (T Version) . . . . . . . . . . . . . . .55°C to +125°C
Storage Temperature Range . . . . . . . . .65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . +300°C
Power Dissipation (Any Package) to +75°C . . . . . 450 mW
Derates above +75°C by . . . . . . . . . . . . . . . . . . .6 mW/°C
*Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those listed in the operational sections of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
AD7871 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)
AD7871 Typical Application
Digital Signal Processing
High Speed Modems
Speech Recognition and Synthesis
Spectrum Analysis
DSP Servo Control
AD7871 Connection Diagram
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