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TCAN4550: TCAN4550 nINT state after RESET

Gilbert Lee
Prodigy 10 points

Part Number: TCAN4550

When TCAN boot up or start, nINT is Low or High by default?
Our test shows MCU reads nINT1 and nINT2 as 0 after RESET, which is already interrupted.
Is this correct?
So FW should clear the Interrupt state over SPI during initialization? 

My assumption was nINT should be High by default.

Thanks,

  • 0
    TI__Mastermind 37401 points

    Hi Gilbert,

    No, the nINT pin is Low by default after a power-on or reset event.  This is because the PWRON (Power ON) Interrupt bit is set in the Interrupt register to indicate the device has powered on and has transitioned to Standby Mode.  This Interrupt bit can be used to indicate the TCAN4550 is now ready to be configured with through the SPI Initialization procedure.

    Note that a hardware or software Reset Event power-cycles the internal Main Core LDO and therefore is equivalent to a Power ON event.

    This also starts the Sleep Wake Error (SWE) Timer which is a failsafe feature used to prevent excessive power consumption if the device was powered on or experienced a false wake-up event while in Sleep Mode.  If the MCU does not clear the PWRON Interrupt or place the device into Normal Mode through the MODE_SEL field within 4 minutes, the device will enter Sleep Mode.

    See the Power Up Timing figure which shows the nINT pin go Low when the device enters Standby Mode, and the Failsafe Feature section of the datasheet for more information on the SWE timer.

    Regards,

    Jonathan