ISO7221A Status:ACTIVE

Product Information

Features

• 1, 5, 25, and 150-Mbps Signaling Rate Options
  • Low Channel-to-Channel Output Skew; 1 ns max
  • Low Pulse-Width Distortion (PWD); 1 ns max
  • Low Jitter Content; 1 ns Typ at 150 Mbps
• Typical 25-Year Life at Rated Voltage
  (see app. note SLLA197 and )
• 4000-V_peak Isolation, 560 V peak V_IORM
  • UL 1577, IEC 60747-5-2 (VDE 0884, Rev 2), IEC 61010-1
  • 50 kV/µs Typical Transient Immunity
• Operates with 3.3-V or 5-V Supplies
• 4 kV ESD Protection
• High Electromagnetic Immunity
• -40°C to 125°C Operating Range
• APPLICATIONS
  • Industrial Fieldbus
    • Modbus
    • Profibus™
    • DeviceNet Data Buses
  • Computer Peripheral Interface
  • Servo Control Interface
  • Data Acquisition

Description

The ISO7220 and ISO7221 are dual-channel digital isolators. To facilitate PCB layout, the channels are oriented in the same direction inthe ISO7220 and in opposite directions in the ISO7221. These devices have a logic input and output buffer separated by TI's silicon-dioxide (SiO₂) isolation barrier, providing galvanic isolation of up to 4000 V. Used in conjunction with isolated power supplies, these devices block high voltage, isolate grounds, and 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 every 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 small capacitance and resulting time constant provide fast operation with signaling rates available from 0 Mbps (dc) to 150 Mbps.The signaling rate of a line is the number of voltage transitions that are made per second expressed in the units bps (bits per second).The A-, B- and C-option devices have TTL input thresholds and a noise filter at the input that prevents transient pulses from being passed to the output of the device. The M-option devices have CMOS V_CC/2 input thresholds and do not have the input noise-filter and the additional propagation delay.

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.

These devices are characterized for operation over the ambient temperature range of -40°C to 125°C.