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APPLICATIONS

DESCRIPTION

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OSC

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PWM

BIAS

POR

ISO722

Only

Filter

Pulse Width

Demodulation

Carrier Detect

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+

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Input

+

Filter

Data MUX

AC Detect

3-State

Output Buffer

IN

EN

Isolation Barrier

DC Channel

AC Channel

FUNCTION DIAGRAM

OUT

POR

ISO721, ISO721M

ISO722, ISO722M

SLLS629B – JANUARY 2006 – REVISED MAY 2006

3.3-V / 5-V HIGH-SPEED DIGITAL ISOLATORS

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Drop-In Replacement for Most Opto and

Magnetic Isolators

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– UL 1577, IEC 60747-5-2 (VDE 0884, Rev. 2)

IEC 61010-1 and CSA Approved

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Industrial Fieldbus

– 50 kV/µs Transient Immunity Typical

– Modbus

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Signaling Rate 0 Mbps to 150 Mbps

– Profibus

– Low-Propagation Delay

– DeviceNet™ Data Buses

– Low-Pulse Skew (Pulse-Width Distortion)

– Smart Distributed Systems (SDS™)

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Low-Power Sleep Mode

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Computer Peripheral Interface

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High-Electromagnetic Immunity

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Servo Control Interface

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Low-Input Current Requirement

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Data Acquisition

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Failsafe Output

The ISO721, ISO721M, ISO722, and ISO722M are digital isolators with a logic input and output buffer separated

conjunction with isolated power supplies, these devices prevent noise currents on a data bus or other circuits

from entering the local ground, and interfering with or damaging sensitive circuitry.

A binary input signal is conditioned, translated to a balanced signal, then differentiated by the capacitive isolation

barrier. Across the isolation barrier, a differential comparator receives the logic transition information, then sets

or resets a flip-flop and the output circuit accordingly. A periodic update pulse is sent across the barrier to

ensure the proper dc level of the output. If this dc-refresh pulse is not received for more than 4 µs, the input is

assumed to be unpowered or not being actively driven, and the failsafe circuit drives the output to a logic high

state.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas

Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

SDS is a trademark of Honeywell.

DeviceNet is a trademark of Open Devicenet Vendors Association, Inc.

PRODUCTION DATA information is current as of publication date.

Copyright © 2006, Texas Instruments Incorporated

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.