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 V_RMS 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.