REV. B

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a

AD7823

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., 2000

2.7 V to 5.5 V, 4.5 s, 8-Bit

ADC in 8-Lead microSOIC/DIP

FUNCTIONAL BLOCK DIAGRAM

CLOCK

OSC

SCLK

AGND

CONVST

SERIAL

PORT

CHARGE

REDISTRIBUTION

DAC

CONTROL

LOGIC

AD7823

COMP

FEATURES

8-Bit ADC with 4

s Conversion Time

Small Footprint 8-Lead microSOIC Package

Specified Over a –40 C to +125 C Temperature Range

Inherent Track-and-Hold Functionality

Operating Supply Range: 2.7 V to 5.5 V

Specifications at 2.7 V to 5.5 V and 5 V

10%

Microcontroller Compatible Serial Interface

Optional Automatic Power-Down

Low Power Operation:

570

W at 10 kSPS Throughput Rate

2.9 mW at 50 kSPS Throughput Rate

“Drop In” Upgrade to 10 Bits Available (AD7810)

APPLICATIONS

Low Power, Hand-Held Portable Applications

Requiring Analog-to-Digital Conversion

with 8-Bit Accuracy, e.g.,

Battery Powered Test Equipment

Battery Powered Communications Systems

GENERAL DESCRIPTION

The AD7823 is a high speed, low power, 8-bit A/D converter

that operates from a single 2.7 V to 5.5 V supply. The part con-

tains a 4

µs typ successive approximation A/D converter, inherent

track-and-hold functionality (with a pseudo differential input)

and a high speed serial interface that interfaces to most microcon-

trollers. The AD7823 is fully specified over a temperature range

of –40

°C to +125°C.

By using a technique that samples the state of the

CONVST

(convert start) signal at the end of a conversion, the AD7823

may be used in an automatic power-down mode. When used in

this mode, the AD7823 powers down automatically at the end

of a conversion and “wakes up” at the start of a new conversion.

This feature significantly reduces the power consumption of the

part at lower throughput rates. The AD7823 can also operate in

a high speed mode where the part is not powered down between

conversions. In this high speed mode of operation, the conver-

sion time of the AD7823 is 4

µs typ. The maximum throughput

rate is dependent on the speed of the serial interface of the

microcontroller.

The part is available in a small, 8-lead 0.3" wide, plastic dual-

in-line package (mini-DIP); in an 8-lead, small outline IC

(SOIC); and in an 8-lead microSOIC package.

PRODUCT HIGHLIGHTS

1. Complete, 8-Bit ADC in 8-Lead Package

The AD7823 is an 8-bit 4

µs ADC with inherent track-and-

hold functionality and a high speed serial interface—all in an

to eliminate the need for an external reference. The result is

a high speed, low power, space saving ADC solution.

2. Low Power, Single Supply Operation

The AD7823 operates from a single +2.7 V to +5.5 V supply

and typically consumes only 9 mW of power. The power

dissipation can be significantly reduced at lower throughput

rates by using the automatic power-down mode, e.g., at a

throughput rate of 10 kSPS the power consumption is only

570

µW.

3. Automatic Power-Down

The automatic power-down mode, whereby the AD7823

“powers down” at the end of a conversion and “wakes up”

before the next conversion, means the AD7823 is ideal for

battery powered applications. See Power vs. Throughput

Rate section.

4. Serial Interface

An easy to use, fast serial interface allows connection to most

popular microprocessors with no external circuitry.