ISO721 Datasheet, PDF (1/22 Pages) Texas Instruments – 3.3-V / 5-V HIGH-SPEED DIGITAL ISOLATORS

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ISO721, ISO721M
ISO722, ISO722M
SLLS629B – JANUARY 2006 – REVISED MAY 2006
3.3-V / 5-V HIGH-SPEED DIGITAL ISOLATORS
FEATURES
• 4000-V_(peak) Isolation
– UL 1577, IEC 60747-5-2 (VDE 0884, Rev. 2)
IEC 61010-1 and CSA Approved
– 50 kV/µs Transient Immunity Typical
• Signaling Rate 0 Mbps to 150 Mbps
– Low-Propagation Delay
– Low-Pulse Skew (Pulse-Width Distortion)
• Low-Power Sleep Mode
• High-Electromagnetic Immunity
• Low-Input Current Requirement
• Failsafe Output
• Drop-In Replacement for Most Opto and
Magnetic Isolators
APPLICATIONS
• Industrial Fieldbus
– Modbus
– Profibus
– DeviceNet™ Data Buses
– Smart Distributed Systems (SDS™)
• Computer Peripheral Interface
• Servo Control Interface
• Data Acquisition
DESCRIPTION
The ISO721, ISO721M, ISO722, and ISO722M are digital isolators with a logic input and output buffer separated
by a silicon oxide (SiO₂) insulation barrier. This barrier provides galvanic isolation of up to 4000 V. Used in
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.
FUNCTION DIAGRAM
Isolation Barrier
DC Channel
OSC
+
PWM
+
_
V_ref
_
+
Filter
Pulse Width
Demodulation
Carrier Detect
POR
Input
IN
+
Filter
AC Channel
BIAS
+
_
V_ref
_
+
POR
Data MUX
AC Detect
3-State
Output Buffer
ISO722
Only
EN
OUT
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.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2006, Texas Instruments Incorporated