ISO721-Q1
www.ti.com ....................................................................................................................................................................................................... SLLS918–JULY 2008
3.3-V / 5-V HIGH-SPEED DIGITAL ISOLATORS
1
FEATURES
•
Qualified for Automotive Applications
•
•
•
•
•
Low-Power Sleep Mode
High Electromagnetic Immunity
Low Input Current Requirement
Failsafe Output
•
4000-V(peak) Isolation
–
–
UL 1577, IEC 60747-5-2 (VDE 0884, Rev 2),
IEC 61010-1
50-kV/s Transient Immunity (Typ)
Drop-In Replacement for Most Optical and
Magnetic Isolators
•
Signaling Rate 0 Mbps to 150 Mbps
–
–
Low Propagation Delay
Low Pulse Skew
(Pulse-Width Distortion)
DESCRIPTION
The ISO721 is a digital isolator 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,
this device prevents 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
+
_
Filter
Pulse Width
Demodulation
OSC
+
PWM
V
ref
_
+
Carrier Detect
POR
POR
BIAS
+
_
Data MUX
AC Detect
3-State
Input
+
Filter
IN
V
ref
_
+
OUT
Output Buffer
AC Channel
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Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
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 © 2008, Texas Instruments Incorporated