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

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

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

V1

+5

AVCC

SCLK

DOUTB

AD7656

OUTPUT

DRIVERS

CONTROL

LOGIC

T/H

VDRIVE

SER/PAR

VDD

REF

VSS

T/H

T/H

T/H

T/H

T/H

V2

16-BIT SAR

16-BIT SAR

16-BIT SAR

16-BIT SAR

16-BIT SAR

V3

V4

V5

V6

DATA/

CONTROL

LINES

OUTPUT

DRIVERS

DOUTC

OUTPUT

DRIVERS

OUTPUT

DRIVERS

CLK

OSC

CONVSTA

CONVSTB CONVSTC

DVCC

4,

BUF

BUF

DOUTA

STBY

94

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

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

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.