250 kSPS, 6-Channel, Simultaneous
Sampling, Bipolar, 16-/14-/12-Bit ADC
Data Sheet
AD7656-1/AD7657-1/AD7658-1
FEATURES
FUNCTIONAL BLOCK DIAGRAM
V
CONVST A CONVST B CONVST C AV
DV
CC CC
DD
Pin and software compatible with AD7656/AD7657/AD7658
featuring reduced decoupling requirements
6 independent ADCs
CS
CLK
OSC
REF
SER/PAR SEL
CONTROL
LOGIC
True bipolar analog inputs
V
DRIVE
Pin-/software-selectable ranges: 10 V, 5 V
Fast throughput rate: 250 kSPS
iCMOS process technology
STBY
BUF
OUTPUT
DRIVERS
DB8/DOUT A
16-/14-/
T/H
V1
V2
V3
V4
V5
V6
12-BIT SAR
Low power
DB6/SCLK
16-/14-/
12-BIT SAR
140 mW at 250 kSPS with 5 V supplies
High noise performance with wide bandwidth
88 dB SNR at 10 kHz input frequency
On-chip reference and reference buffers
High speed parallel, serial, and daisy-chain interface modes
High speed serial interface
SPI/QSPI™/MICROWIRE™/DSP compatible
Standby mode: 315 µW maximum
64-lead LQFP
T/H
T/H
T/H
T/H
T/H
OUTPUT
DRIVERS
DB9/DOUT B
BUF
BUF
16-/14-/
12-BIT SAR
OUTPUT
DRIVERS
DB10/DOUT C
16-/14-/
12-BIT SAR
DATA/
CONTROL
LINES
OUTPUT
DRIVERS
16-/14-/
12-BIT SAR
RD
WR/REF
EN/DIS
16-/14-/
12-BIT SAR
APPLICATIONS
AD7656-1/AD7657-1/AD7658-1
Power line monitoring and measuring systems
Instrumentation and control systems
Multiaxis positioning systems
V
AGND
DGND
SS
Figure 1.
GENERAL DESCRIPTION
The AD7656-1/AD7657-1/AD7658-11 are reduced decoupling pin-
and software-compatible versions of AD7656/AD7657/AD7658.
The AD7656-1/AD7657-1/AD7658-1 devices contain six 16-/
14-/12-bit, fast, low power successive approximation ADCs in
a package designed on the iCMOS® process (industrial CMOS).
iCMOS is a process combining high voltage silicon with submicron
CMOS and complementary bipolar technologies. It enables the
development of a wide range of high performance analog ICs
capable of 33 V operation in a footprint that no previous generation
of high voltage parts could achieve. Unlike analog ICs using conven-
tional CMOS processes, iCMOS components can accept bipolar
input signals while providing increased performance, which
dramatically reduces power consumption and package size.
The conversion process and data acquisition are controlled
using the CONVST signals and an internal oscillator. Three
CONVST pins (CONVST A, CONVST B, and CONVST C)
allow independent, simultaneous sampling of the three ADC
pairs. The AD7656-1/AD7657-1/AD7658-1 have a high speed
parallel and serial interface, allowing the devices to interface with
microprocessors or DSPs. When the serial interface is selected,
each part has a daisy-chain feature that allows multiple ADCs to
connect to a single serial interface. The AD7656-1/AD7657-1/
AD7658-1 can accommodate true bipolar input signals in the
4 × VREF and 2 × VREF ranges. Each AD7656-1/AD7657-1/
AD7658-1 also contains an on-chip 2.5 V reference.
PRODUCT HIGHLIGHTS
The AD7656-1/AD7657-1/AD7658-1 feature throughput rates
of up to 250 kSPS. The parts contain low noise, wide bandwidth
track-and-hold amplifiers that can handle input frequencies
up to 4.5 MHz.
1. Six 16-/14-/12-bit, 250 kSPS ADCs on board.
2. Six true bipolar, high impedance analog inputs.
3. High speed parallel and serial interfaces.
4. Reduced decoupling requirements and reduced bill of
materials cost compared with the AD7656/AD7657/
AD7658 devices.
1 Protected by U.S. Patent No. 6,731,232.
Rev. D
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