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TCAN1145-Q1: POWERON bit

Sherry Liang
Genius 10255 points
Part Number: TCAN1145-Q1

Dear team,

I want to check with you when the register POWERON bit will be set. My customer have a test, after Vsup turn off, give 12V power to Vsup pin again when Vsup decrease to 3V-7V, the POWERON bit won't be set. In my understanding, the POWERON bit will be set only when Vsup falls below 1.85V and rises above 3.9V, right? Vsup undervoltage won't cause POWERON bit to be set, right?

Thanks & Best Regards,

Sherry

  • 0
    TI__Genius 15345 points

    Hi Sherry,

    The TCAN1145 and all of our other SPI devices will always have the PWRON bit set whenever VSUP has passed the rising threshold so VSUP(PU)R or 3.9V max. If your VSUP has under voltaged than you won't be able to communicate on SPI and you won't be able to read the PWRON bit anyway. The device will be stuck in an unpowered state and nothing on the device will work.

    So if you are communicating with the device through SPI to read the PWRON bit then it will always be set because you need to be powered on in order to communicate.

    Does that make sense?

    Best,

    Chris

  • +1
    TI__Guru 74292 points

    Sherry,

    That is correct, the POWERON flag only asserts when there is a full power-on reset of the transceiver. This threshold is lower than the under voltage threshold.

    Regards,

    Eric Hackett