ISO1500 Basic Isolated Transceiver

By Texas Instruments 537

ISO1500 Basic Isolated Transceiver

Texas Instruments' ISO1500 device is a galvanically-isolated differential line transceiver designed for TIA/EIA RS-485 and RS-422 applications. The device has a 3-channel digital isolator and an RS-485 transceiver in an ultra-small 16-pin SSOP package. The bus pins of the transceiver are protected against IEC ESD contact discharge and IEC EFT events. The receiver output has a fail-safe for bus open, short, and idle conditions. The small solution size of the ISO1500 greatly reduces the board space that is required compared to other integrated isolated RS-485 solutions or discrete implementation with optocouplers and a non-isolated RS-485 transceiver.

The device is used for long distance communications. Isolation breaks the ground loop between the communicating nodes allowing for a larger common-mode voltage range. The symmetrical isolation barrier of the device is tested to provide 3,000 VRMS of isolation for one minute per UL 1577 between the bus-line transceiver and the logic-level interface.

The ISO1500 device can operate from 1.71 V to 5.5 V on side one allowing the device to interface with low-voltage FPGAs and ASICs. The supply voltage on side two is from 4.5 V to 5.5 V. The device supports a wide operating ambient temperature range from -40°C to +125°C.

  • Meets or exceeds TIZ/EIA-485-A requirements
  • Half-duplex transceiver
  • Low EMI 1 Mbps data rate
  • 1/8-unit load: up to 256 nodes on bus
  • Fail-safe receiver for bus open, short, and idle
  • Logic-side supply (VCC1): 1.71 V to 5.5 V and bus-side supply (VCC2): 4.5 V to 5.5 V
  • High common-mode transient immunity: 100 kV/µs (typ.)
  • Extended temperature range: -40°C to +125°C
  • Glitch-free power-up and power-down for hot plug-in
  • Ultra-small SSOP (DBQ-16) package
  • Safety-related certifications:
    • All certifications planned
    • 4,242 VPK VIOTM and 566 VPK VIORM per DIN V VDE V 0884-11:2017-01
    • 3,000 VRMS isolation for one minute per UL 1577
    • IEC 60950, IEC 60601, and EN 61010 certifications
    • CQC, TUV, and CSA certifications
  • Electricity meters
  • Protection relays
  • HVAC systems and building automation
  • Motor drives
  • Factory automation and controls