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 VPK 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.
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.
• 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
• 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-VPK VIOTM, 560
– 2500 VRMS Isolation per UL 1577
– CSA Approved for Component Acceptance
Notice 5A and IEC 60950-1
• Industrial Fieldbus
– DeviceNet™ Data Buses
– Smart Distributed Systems (SDS™)
• Computer Peripheral Interface
• Servo Control Interface
• Data Acquisition
Texas Instruments introduction - Texas Instruments Incorporated (TI) is a global semiconductor design and manufacturing company that develops analog ICs and embedded processors. By employing the world's brightest minds, TI creates innovations that shape the future of technology. TI is helping more than 100,000 customers transform the future, today.