ISO721_1007 Datasheet, PDF (1/29 Pages) Texas Instruments – 3.3-V / 5-V HIGH-SPEED DIGITAL ISOLATORS

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ISO721, ISO721M
ISO722, ISO722M
SLLS629J – JANUARY 2006 – REVISED JULY 2010
3.3-V / 5-V HIGH-SPEED DIGITAL ISOLATORS
Check for Samples: ISO721, ISO721M, ISO722, ISO722M
FEATURES
1
•23 4000-V_(peak) Isolation, 560-V_peak V_IORM
– UL 1577, IEC 60747-5-2 (VDE 0884, Rev. 2)
IEC 61010-1, IEC 60950-1 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 dioxide (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 ms, 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
1
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.
2
DeviceNet is a trademark of Open Devicenet Vendors Association, Inc.
3
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 © 2006–2010, Texas Instruments Incorporated