250 kSPS, 6-Channel, Simultaneous
Sampling, Bipolar 16-/14-/12-Bit ADC
Preliminary Technical Data
AD7656-1/AD7657-1/AD7658-1
FEATURES
FUNCTIONAL BLOCK DIAGRAM
AV
DV
Six independent ADCs
CC
CC
CONVSTB
V
CONVSTC
CONVSTA
DD
True bipolar analog inputs
CS
SER/PAR
Pin-/software-selectable ranges: ±10 V, ±± V
Fast throughput rate: 2±0 kSPS
iCMOSTM process technology
Low power
TBD mW at 2±0 kSPS with ± V supplies
Wide input bandwidth
TBD dB SNR at ±0 kHz input frequency
On-chip reference and reference buffers
Parallel, serial, and daisy-chain interface modes
High speed serial interface
SPI®-/QSPI™-/MICROWIRE™-/DSP-compatible
Standby mode: 100 µW max
CLK
OSC
CONTROL
LOGIC
V
DRIVE
STBY
REF
BUF
OUTPUT
DRIVERS
D
OUT
A
V
V
T/H
T/H
16/14/12-BIT SAR
16/14/12-BIT SAR
1
SCLK
2
3
OUTPUT
DRIVERS
D
OUT
B
BUF
V
T/H
T/H
16/14/12-BIT SAR
16/14/12-BIT SAR
OUTPUT
DRIVERS
D
OUT
C
V
4
DATA/
CONTROL
LINES
OUTPUT
DRIVERS
BUF
64-lead LQFP
16/14/12-BIT SAR
V
V
T/H
5
RD
WR
APPLICATIONS
16/14/12-BIT SAR
T/H
V
6
Power line monitoring systems
Instrumentation and control systems
Multi-axis positioning systems
AD7656-1/AD7657-1/AD7658-1
AGND
SS
DGND
Figure 1.
GENERAL DESCRIPTION
CONVST pins allow independent, simultaneous sampling of
the three ADC pairs. The AD7656-1/AD7657-1/AD7658-1 all
have a high speed parallel and serial interface, allowing the
devices to interface with microprocessors or DSPs. In serial
interface mode, the parts have 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 range and 2 × VREF range.
The AD7656-1/ AD7657-1/AD7658-1 also contain an on-chip
2.5 V reference.
The AD7656-1/AD7657-1/AD7658-11 contain six 16-/14-/12-
bit, fast, low power, successive approximation ADCs all in the
one package that is 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 conventional CMOS
processes, iCMOS components can accept bipolar input signals
while providing increased performance, which dramatically
reduces power consumption and package size.
PRODUCT HIGHLIGHTS
1. Six 16-/14-/12-bit, 250 kSPS ADCs on board.
2. Six true bipolar, high impedance analog inputs.
3. Parallel and high speed serial interfaces.
The AD7656-1/AD7657-1/AD7658-1 feature throughput rates
up to 250 kSPS. The parts contain low noise, wide bandwidth,
track-and-hold amplifiers that can handle input frequencies
up to 12 MHz.
The conversion process and data acquisition are controlled
using CONVST signals and an internal oscillator. Three
1 Protected by U.S. Patent No. 6,731,232.
Rev. PrC
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