250 kSPS, 6-Channel,Simultaneous
Sampling, Bipolar 12/14/16-Bit ADC
Preliminary Technical Data
AD7658/AD7657/AD7656*


Rev. PrI
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FEATURES
6 Independent ADCs
True Bipolar Analog Inputs
Pin/Software Selectable Ranges:- ±10V, ±5V
Fast throughput rate: 250 kSPS
Specified for VCC of 4.5 V to 5.5 V
Low power
160mW at 250 kSPS with 5 V supplies
Wide input bandwidth:
85 dB SNR at 50 kHz input frequency
On-chip Reference and Reference Buffers
Parallel and Serial Interface
High speed serial interface
SPI/QSPI/µWire/DSP compatible
Standby mode: 5 µA max
iCMOS
TM
Process Technology
64 LQFP package

APPLICATIONS
Power Line Monitoring systems
Instrumentation and control systems
Multi-axis positioning systems

FUNCTIONAL BLOCK DIAGRAM
16-BIT SAR
BUF
AGND DGND
V
1
X43X53
AV
CC
SCLK
D
OUT
B
AD7656
OUTPUT
DRIVERS
CONTROL
LOGIC
T/H
V
DRIVE
SER/PAR
V
DD
REF
V
SS
T/H
T/H
T/H
T/H
T/H
V
2 16-BIT SAR
16-BIT SAR
16-BIT SAR
16-BIT SAR
16-BIT SAR
V
3
V
4
V
5
V
6
DATA/
CONTROL
LINES
OUTPUT
DRIVERS
D
OUT
C
OUTPUT
DRIVERS
OUTPUT
DRIVERS
CLK
OSC
CONVSTA
CONVSTB CONVSTC
DV
CC
X52X44
X42X55X46
X42X55X46
X44
X4FX55X54
X41
X53X54X42X59
X57X52

Figure 1.
GENERAL DESCRIPTION
The AD7658/AD7657/AD7656 contain six 12/14/16-bit, fast, low
power, successive approximation ADCs all in the one package.
The AD7658/AD7657/AD7656 core operates from a single 4.5
V to 5.5 V power supply and features throughput rates up to 250
kSPS. The parts contain low noise, wide bandwidth track-and-
hold amplifiers that can handle input frequencies up to 8 MHz.
The conversion process and data acquisition are controlled
using CONVST signals and an internal oscillator. Three
CONVST pins allow independent simultaneous sampling of the
three ADC pairs. The AD7658/AD7657/AD7656 have both a
high speed parallel and serial interface allowing the devices to
interface with microprocessors or DSPs. When in Serial
interface mode these parts have a Daisy Chain feature allowing
multiple ADCs to connect to a single serial interface. The
AD7658/AD7657/AD7656 can accommodate true bipolar input
signals in the ±10V range and ±5V range . They contain a 2.5V
internal reference and can also accept an external reference. If a
3V external reference is applied to the VREF pin, the ADCs can
accommodate a true bipolar ±12V analog input range. VDD and
VSS supplies of ±12V are required for this ±12V input range.

PRODUCT HIGHLIGHTS
1. Six 12/14/16-bit 250 kSPS ADCs on board.
2. Six true bipolar high impedance analog inputs.
3. The AD7658/AD7657/AD7656 feature both a parallel and
a high speed serial interface.

* Protected by U.S. Patent No. 6,731,232
iCMOS
TM
Process Technology
For analog systems designers within industrial/instrumentation equipment OEMs who need high performance ICs at higher-voltage levels, iCMOS is a technology platform
that enables the development of analog ICs capable of 30V and operating at +/- 15V supplies while allowing dramatic reductions in power consumption and package size, and
increased AC and DC performance.