AD7870A_15 Datasheet, PDF (1/12 Pages) Analog Devices – LC MOS Complete, 12-Bit, 100 kHz , Sampling ADC

a LC2MOS
Complete, 12-Bit, 100 kHz , Sampling ADC
AD7870A
FEATURES
Complete Monolithic 12-Bit ADC with:
2 ␮s Track/Hold Amplifier
8 ␮s A/D Converter
On-Chip Reference
Laser-Trimmed Clock
Parallel, Byte and Serial Digital Interface
70 dB SNR at 10 kHz Input Frequency
57 ns Data Access Time
Low Power—60 mW typ
APPLICATIONS
Digital Signal Processing
Speech Recognition and Synthesis
Spectrum Analysis
High Speed Modems
DSP Servo Control
FUNCTIONAL BLOCK DIAGRAM
GENERAL DESCRIPTION
The AD7870A is a fast, complete, 12-bit A/D converter. It con-
sists of a track/hold amplifier, 8 µs successive approximation
ADC, 3 V buried Zener reference and versatile interface logic.
The ADC features a self-contained internal clock that is laser
trimmed to guarantee accurate control of conversion time. No
external clock timing components are required; the on-chip
clock may be overridden by an external clock if required.
AD7870A offers a choice of three data output formats: a single,
parallel, 12-bit word, two 8-bit bytes or serial data. Fast bus
access times and standard control inputs ensure easy interfacing
to modern microprocessors and digital signal processors.
The AD7870A operates from ± 5 V power supplies, accepts
bipolar input signals of ± 3 V and can convert full power signals
up to 50 kHz.
In addition to the traditional dc accuracy specifications such as
linearity, full-scale and offset errors, the AD7870A is also fully
specified for dynamic performance parameters including har-
monic distortion and signal-to-noise ratio.
The AD7870A is fabricated in Analog Devices’ linear compati-
ble CMOS (LC²MOS) process, a mixed technology process that
combines precision bipolar circuits with low power CMOS logic.
The part is available in a 24-pin, 0.3-inch wide, plastic dual in-
line package (DIP).
PRODUCT HIGHLIGHTS
1. Complete 12-bit ADC on a chip.
The AD7870A is the most complete monolithic ADC avail-
able and combines a 12-bit ADC with internal clock, track/
hold amplifier and reference on a single chip.
2. Dynamic specifications for DSP users.
The AD7870A is fully specified and tested for ac parameters,
including signal-to-noise ratio, harmonic distortion and inter-
modulation distortion. Key digital timing parameters are also
tested and guaranteed over the full operating temperature
range.
3. Fast microprocessor interface.
Data access times of 57 ns make the AD7870A compatible
with modern 8- and 16-bit microprocessors and digital signal
processors.
REV. 0
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© Analog Devices, Inc., 1997