REV. D

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 that

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

under any patent or patent rights of Analog Devices. Trademarks and

registered trademarks are the property of their respective owners.

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

Tel: 781/329-4700

www.analog.com

Fax: 781/326-8703

© 2004 Analog Devices, Inc. All rights reserved.

1 MSPS, 12-/10-/8-Bit ADCs

in 6-Lead SOT-23

*Protected by U.S.Patent No. 6,681,332.

FEATURES

Fast Throughput Rate: 1 MSPS

Low Power:

3.6 mW Typ at 1 MSPS with 3 V Supplies

15 mW Typ at 1 MSPS with 5 V Supplies

Wide Input Bandwidth:

70 dB SNR at 100 kHz Input Frequency

Flexible Power/Serial Clock Speed Management

No Pipeline Delays

High Speed Serial Interface

Standby Mode: 1

A Max

6-Lead SOT-23 Package

APPLICATIONS

Battery-Powered Systems

Personal Digital Assistants

Medical Instruments

Mobile Communications

Instrumentation and Control Systems

Data Acquisition Systems

High Speed Modems

Optical Sensors

FUNCTIONAL BLOCK DIAGRAM

T/H

AD7476/AD7477/AD7478

SCLK

SDATA

CS

GND

8-/10-/12-BIT

SUCCESSIVE-

APPROXIMATION

ADC

CONTROL

LOGIC

GENERAL DESCRIPTION

The AD7476/AD7477/AD7478 are, respectively, 12-bit, 10-bit,

and 8-bit, high speed, low power, successive-approximation

ADCs. The parts operate from a single 2.35 V to 5.25 V power

supply and feature throughput rates up to 1 MSPS. The parts

contain a low noise, wide bandwidth track-and-hold amplifier

that can handle input frequencies in excess of 6 MHz.

The conversion process and data acquisition are controlled

using

CS and the serial clock, allowing the devices to interface

with microprocessors or DSPs. The input signal is sampled on

the falling edge of

CS and the conversion is also initiated at this

point. There are no pipeline delays associated with the part.

The AD7476/AD7477/AD7478 use advanced design techniques

to achieve very low power dissipation at high throughput rates.

allows the widest dynamic input range to the ADC. Thus the

rate is determined by the SCLK.

PRODUCT HIGHLIGHTS

1. First 12-/10-/8-Bit ADCs in a SOT-23 Package.

2. High Throughput with Low Power Consumption.

3. Flexible Power/Serial Clock Speed Management.

The conversion rate is determined by the serial clock, allowing

the conversion time to be reduced through the serial clock

speed increase. This allows the average power consumption

to be reduced while not converting. The part also features a

shutdown mode to maximize power efficiency at lower

throughput rates. Current consumption is 1

µA maximum

when in shutdown.

4. Reference Derived from the Power Supply.

5. No Pipeline Delay.

The parts feature a standard successive-approximation ADC

with accurate control of the sampling instant via a

CS input

and once-off conversion control.