REV. B

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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

AD7887

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

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 1999

+2.7 V to +5.25 V, Micropower, 2-Channel,

125 kSPS, 12-Bit ADC in 8-Lead SOIC

FUNCTIONAL BLOCK DIAGRAM

SAR + ADC

CONTROL LOGIC

GND

AIN0

SCLK

DOUT

DIN

AD7887

CS

T/H

I/P

MUX

BUF

CHARGE

REDISTRIBUTION

DAC

COMP

SOFTWARE

CONTROL

LATCH

AIN1

2.5V

REF

SPORT

FEATURES

Flexible Power/Throughput Rate Management

Shutdown Mode: 1

A Max

One/Two Single-Ended Inputs

Serial Interface: SPI™/QSPI™/MICROWIRE™/DSP

Compatible

8-Lead Narrow SOIC and

SOIC Packages

APPLICATIONS

Battery-Powered Systems (Personal Digital Assistants,

Medical Instruments, Mobile Communications)

Instrumentation and Control Systems

High Speed Modems

GENERAL DESCRIPTION

The AD7887 is a high speed, low power, 12-bit ADC that oper-

ates from a single +2.7 V to +5.25 V power supply. The AD7887

is capable of 125 kSPS throughput rate. The input track-and-

hold acquires a signal in 500 ns and features a single-ended

sampling scheme. The output coding for the AD7887 is straight

binary and the part is capable of converting full power signals up to

2.5 MHz.

The AD7887 can be configured for either dual or single chan-

nel operation, via the on-chip Control Register. There is a

default single-channel mode that allows the AD7887 to be

operated as a read-only ADC. In single-channel operation,

overdriven by an external reference to provide the reference

voltage for the part. This external reference voltage has a range

function, providing a second analog input channel. In this case,

a result, the input voltage range on both the AIN0 and AIN1

CMOS construction ensures low power dissipation of typically

2 mW for normal operation and 3

µW in power-down mode.

The part is available in an 8-lead, 0.15-inch-wide narrow body

SOIC and an 8-lead

µSOIC package.

PRODUCT HIGHLIGHTS

1. Smallest 12-bit dual/single-channel ADC; 8-lead

µSOIC

package.

2. Lowest power 12-bit dual/single-channel ADC.

3. Flexible power management options including automatic

power-down after conversion.

4. Read-Only ADC capability.

6. Versatile serial I/O port (SPI/QSPI/MICROWIRE/DSP

compatible).

SPI and QSPI are trademarks of Motorola, Inc.

MICROWIRE is a trademark of National Semiconductor Corporation.