AD7874AR View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

AD7874AR

LC2MOS 4-Channel, 12-Bit Simultaneous Sampling Data Acquisition System

Analog Devices 

a LC2MOS 4-Channel, 12-Bit Simultaneous

Sampling Data Acquisition System

AD7874

FEATURES

Four On-Chip Track/Hold Amplifiers

Simultaneous Sampling of 4 Channels

Fast 12-Bit ADC with 8 ␮s Conversion Time/Channel

29 kHz Sample Rate for All Four Channels

On-Chip Reference

؎10 V Input Range

؎5 V Supplies

APPLICATIONS

Sonar

Motor Controllers

Adaptive Filters

Digital Signal Processing

GENERAL DESCRIPTION

The AD7874 is a four-channel simultaneous sampling, 12-bit

data acquisition system. The part contains a high speed 12-bit

ADC, on-chip reference, on-chip clock and four track/hold am-

plifiers. This latter feature allows the four input channels to be

sampled simultaneously, thus preserving the relative phase

information of the four input channels, which is not possible if

all four channels share a single track/hold amplifier. This makes

the AD7874 ideal for applications such as phased-array sonar

and ac motor controllers where the relative phase information is

important.

The aperture delay of the four track/hold amplifiers is small and

specified with minimum and maximum limits. This allows sev-

eral AD7874s to sample multiple input channels simultaneously

without incurring phase errors between signals connected to

several devices. A reference output/reference input facility also

allows several AD7874s to be driven from the same reference

source.

In addition to the traditional dc accuracy specifications such as

linearity, full-scale and offset errors, the AD7874 is also fully

specified for dynamic performance parameters including distor-

tion and signal-to-noise ratio.

The AD7874 is fabricated in Analog Devices’ Linear Compat-

ible CMOS (LC2MOS) process, a mixed technology process

that combines precision bipolar circuits with low-power CMOS

logic. The part is available in a 28-pin, 0.6" wide, plastic or her-

metic dual-in-line package (DIP), in a 28-terminal leadless ce-

ramic chip carrier (LCCC) and in a 28-pin SOIC.

FUNCTIONAL BLOCK DIAGRAM

INT CS RD CONVST VDD VDD

VIN1

TRACK/

HOLD 1

CONTROL LOGIC

INTERNAL

CLOCK

CLK

VIN2

TRACK/

HOLD 2

VIN3

TRACK/

HOLD 3

VIN4

TRACK/

HOLD 4

MUX

COMP

SAR

DATA

REGISTERS

DB0

DB11

REFERENCE

BUFFER

AD7874

12-BIT

DAC

REF IN

3V

REFERENCE

REF OUT

AGND DGND VSS

PRODUCT HIGHLIGHTS

1. Simultaneous Sampling of Four Input Channels.

Four input channels, each with its own track/hold amplifier,

allow simultaneous sampling of input signals. Track/hold ac-

quisition time is 2 µs, and the conversion time per channel is

8 µs, allowing 29 kHz sample rate for all four channels.

2. Tight Aperture Delay Matching.

The aperture delay for each channel is small and the aperture

delay matching between the four channels is less than 4 ns.

Additionally, the aperture delay specification has upper and

lower limits allowing multiple AD7874s to sample more than

four channels.

3. Fast Microprocessor Interface.

The high speed digital interface of the AD7874 allows direct

connection to all modern 16-bit microprocessors and digital

signal processors.

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.

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

Tel: 617/329-4700

Fax: 617/326-8703

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