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ISO1500: Failsafe receiver

Part Number: ISO1500

How does the ISO1500 receiver implement the failsafe protection? Is it done by an integrated pull-up from A to VCC2 and a pull-down from B to GND2? Or is it solved by shifting the receiver thresholds? The question behind is: If it is done by resistors, then the other non-failsafe protected RS485 receivers w/o biasing resistors connected to the bus are covered at least against idle bus conditions! But if only the receiver thresholds are shifted we better add external biasing resistors…

  • Hi Claude:

    Thanks for posting your question E2E!

    Failsafe protection of ISO1500 is implemented by shifting the receiver input thresholds. For a detailed description, please refer to Section 8.3.2 of the datasheet.

    Yes, you'll need external failsafe biasing resistors to protect non-failsafe receivers.

    Regards,

    Dushmantha