REV. C

Information furnished by Analog Devices is believed to be accurate and

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

16-Bit, High Speed Sampling ADCs

AD7884/AD7885

© Analog Devices, Inc., 1995

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

Tel: 617/329-4700

Fax: 617/326-8703

FUNCTIONAL BLOCK DIAGRAMS

±5V F

±5V S

±3V F ±3V S

16-BIT

ACCURATE

DAC

AD7884

TIMER

CONTROL

DGND

CS

RD

BUSY

DB15

V

S

REF+

REF+

V

F

AGNDS

GND

DB0

CONVST

IN

R7

2k

Ω

R8

2k

Ω

9

9

9

16

16

5k

Ω

3k

Ω

3k

Ω

4k

Ω

4k

Ω

R1

R2

R3

R4

C1

SW1

R5

SW2

SW3

2k

Ω

R6

A1

A2

9-BIT

ADC

LATCH

+

ALU

O

U

T

P

U

T

D

R

I

V

E

R

S

IN

IN

IN

±5V F

±5V S

16-BIT

ACCURATE

DAC

AD7885

TIMER

CONTROL

DGND

CS

RD

BUSY

DB7

V

S

REF+

V

F

REF+

AGNDS

GND

DB0

CONVST

IN

R7

2k

Ω

R8

2k

Ω

9

9

9

16

8

5k

Ω

3k

Ω

2k

Ω

4k

Ω

4k

Ω

R1

R2

3k

Ω

R3

R4

C1

SW1

R5

SW2

SW3

R6

A1

A2

9-BIT

ADC

LATCH

+

ALU

O

U

T

P

U

T

D

R

I

V

E

R

S

IN

IN

±3V

HBEN

FEATURES

Monolithic Construction

Fast Conversion: 5.3

s

High Throughput: 166 kSPS

Low Power: 250 mW

APPLICATIONS

Automatic Test Equipment

Medical Instrumentation

Industrial Control

Data Acquisition Systems

Robotics

GENERAL DESCRIPTION

The AD7884/AD7885 is a 16-bit monolithic analog-to-digital

converter with internal sample-and-hold and a conversion time

of 5.3

µs. The maximum throughput rate is 166 kSPS. It uses a

two pass flash architecture to achieve this speed. Two input

ranges are available:

±5 V and ±3 V. Conversion is initiated by

the CONVST signal. The result can be read into a microproces-

sor using the CS and RD inputs on the device. The AD7884 has

a 16-bit parallel reading structure while the AD7885 has a byte

reading structure. The conversion result is in 2s complement

code.

The AD7884/AD7885 has its own internal oscillator which con-

trols conversion. It runs from

±5 V supplies and needs a V

REF+

of +3 V.

The AD7884 is available in a 40-pin plastic DIP package and in

a 44-pin PLCC package.

The AD7885 is available in a 28-pin plastic DIP package and

the AD7885A is available in a 44-pin PLCC package.