Isolated Sigma-Delta Modulator

Preliminary Technical Data

AD7400/AD7401

FEATURES

Up to 20 MHz Data Rate (AD7401)

10 MHz Data Rate (AD7400)

±4 LSB INL @16 Bits

Onboard Digital Isolator

Onboard Reference

Low Power Operation:

15 mA @ 5 V

-40 C to +105 C Operating Range

16-ld SOIC Package

Safety and Regulatory Approvals

UL Recognition

CSA Component Acceptance Notice ~5A

VDE Certificate of Conformity

DIN EN 60747-5-2 (VDE 0884 Part 2):2003-01

DIN EN 60950 (VDE 0805): 2001-12; EN 60950:2000

APPLICATIONS

AC Motor Control

Data Acquisition Systems

A/D + Opto-Isolator Replacement

GENERAL DESCRIPTION

The AD7400/AD7401 are 2nd order sigma-delta modulators

that convert an analog input signal into a high speed 1-bit data

stream with onboard digital isolation based on Analog Devices’

iCoupler® technology. The AD7400/AD7401 operate from a 5 V

power supply and accept a differential input signal of ±200 mV.

The analog input is continuously sampled by the analog

modulator, eliminating the need for external sample and hold

circuitry. The input information is contained in the output

stream as a density of ones with data rates up to 20MHz. The

original information can be reconstructed with an appropriate

The serial interface is digitally isolated. High-speed CMOS,

FUNCTIONAL BLOCK DIAGRAM

UPDATE

ENCODE

DECODE

WATCHDOG

T/H

VDD1

Σ-∆ ADC

MCLKOUT*

CONTROL LOGIC

MDAT

GND1

VDD2

GND2

VIN+

VIN-

REF

BUF

UPDATE

ENCODE

DECODE

WATCHDOG

*MCLKIN pin on AD7401

Rev. PrH

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