REV. 0

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reliable. However, no responsibility is assumed by Analog Devices for its

use, nor for any infringements of patents or other rights of third parties

which may result from its use. No license is granted by implication or

otherwise under any patent or patent rights of Analog Devices.

a

8-Bit, 4-Channel Data

Acquisition System

AD8401

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

FUNCTIONAL BLOCK DIAGRAM

V

OUT

DGND

AG

DAC

AG

ADC

DATA I/O

(8 BITS)

M

U

X

T/H

8-BIT ADC

1.25 REF

8-BIT

DAC

RS

INT

BUSY

ST

DAC REG

ADC REG

CONTROL LOGIC

A0 A1

V

RD

WR

CLK

CS

AD8401

V

A

IN

V

B

IN

V

C

IN

V

D

IN

FEATURES

2

s ADC with T/H

4-Channel MUX

AD899 Compatible

+5 Volt Operation

On-Chip Reference

4

s Voltage Output DAC

Fast Bus Access Time—75 ns

APPLICATIONS

Servo Controls

Digitally Controlled Calibration

Process Control Equipment

GENERAL DESCRIPTION

The AD8401 is a complete data acquisition and control system

containing ADC, DAC, 4-channel MUX, and internal voltage

reference. Built using CBCMOS, this monolithic circuit offers

the user a complete system with very high package density and

reliability.

The converter is a successive approximation ADC with T/H,

and is capable of operating with conversion times as short as

2

µs. Analog input bandwidth is 200 kHz, and DAC output volt-

age settling time is less than 4

µs, making the AD8401 capable

of controlling servo loops with speed and precision.

The 8-bit data interface provides both read and write operation

for parallel bus interfaces to microcontrollers and DSP proces-

sors. An external 5 MHz clock sets the 2

µs conversion rate.

Slower clocks reduce the conversion time and the internal power

dissipation. The standard control lines: Reset, Busy, Interrupt,

Read and Write complete the handshaking signals for micro-

processor communication. A start trigger ST input allows pre-

cise sampling intervals in synchronous sampling applications.

The input multiplexer addressing is designed for direct interface

to the AD899 hard-disk drive, read-channel device with no extra

hardware or special software. Analog input range levels are like-

wise compatible with the AD899.

The AD8401 is designed to operate from a single +5 volt sup-

ply, which will give an ADC input range of 0 V to 3.0 V, and

DAC output range of 0 V to 2.5 V.

The AD8401 is offered in the SOIC-28 surface mount package,

and is guaranteed to operate over the extended industrial tem-

perature range of –40

°C to +85°C.