ISO721_15 Datasheet, PDF (1/37 Pages) Texas Instruments – Single Channel High-Speed Digital Isolators

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ISO721, ISO721M, ISO722, ISO722M
SLLS629L – JANUARY 2006 – REVISED OCTOBER 2015
ISO72x Single Channel High-Speed Digital Isolators
1 Features
•1 100 and 150-Mbps Signaling Rate Options
• Low Propagation Delay
• Low Pulse Skew
• Low-Power Sleep Mode
• High Electromagnetic Immunity
• Low Input-Current Requirement
• Failsafe Output
• Drop-In Replacement for Most Opto and Magnetic
Isolators
• Operates from 3.3 V and 5 V Supplies
• -40°C to 125°C Operating Temperature Range
• 50 kV/µs Transient Immunity, Typical
• Safety and Regulatory Approvals
– VDE Basic Insulation with 4000-V_PK V_IOTM, 560
V_PK V_IORM
– 2500 V_RMS Isolation per UL 1577
– CSA Approved for Component Acceptance
Notice 5A and IEC 60950-1
2 Applications
• Industrial Fieldbus
– Modbus
– Profibus
– DeviceNet™ Data Buses
– Smart Distributed Systems (SDS™)
• Computer Peripheral Interface
• Servo Control Interface
• Data Acquisition
3 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_PK per VDE. 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.
1
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.
The symmetry of the dielectric and capacitor within
the integrated circuitry provides for close capacitive
matching, and allows fast transient voltage changes
between the input and output grounds without
corrupting the output. The small capacitance and
resulting time constant provide for fast operation with
signaling rates from 0 Mbps (DC) to 100 Mbps for the
ISO721 and the ISO722 devices, and 0 Mbps to 150
Mbps with the ISO721M and the ISO722M devices.
These devices require two supply voltages of 3.3 V, 5
V, or any combination. All inputs are 5-V tolerant
when supplied from a 3.3-V supply and all outputs
are 4 mA CMOS.
The ISO722 and ISO722M devices include an active-
low output enable that when driven to a high logic
level, places the output in a high-impedance state
and turns off internal bias circuitry to conserve power.
Both the ISO721 and ISO722 devices have TTL input
thresholds and a noise filter at the input that prevent
transient pulses of up to 2 ns in duration from being
passed to the output of the device.
The ISO721M and ISO722M devices have CMOS
V_CC / 2 input thresholds, but do not have the noise-
filter and the additional propagation delay. These
features of the ISO721M device also provide for
reduced-jitter operation.
The ISO721, ISO721M, ISO722, and ISO722M
devices are characterized for operation over the
ambient temperature range of –40°C to 125°C.
Device Information⁽¹⁾
PART NUMBER
PACKAGE
BODY SIZE (NOM)
ISO721
SOP (8)
9.50mm x 6.57mm
ISO721
ISO721M
ISO722
SOIC (8)
4.90mm x 3.91mm
ISO722M
(1) For all available packages, see the orderable addendum at
the end of the datasheet.
Simplified Schematic
V_CC1
V_CC2
Isolation
Capacitor
IN
OUT
GND1
GND2
EN (ISO722/M-only)
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.