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TCAN1057AV-Q1: Question about TCAN1057AV-Q1 external pull -ups on TXD, Silent pin.

SUNHO PARK
Prodigy 10 points

Part Number: TCAN1057AV-Q1

Hi, this is Sun Ho Park in LG electronics.

I have a question about a description of red box comment in TCAN1057 datasheet.

Does this mean,

When TCAN1057 receives open-drain output from AP or MCU , external pull-up resistor is needed on TXD pin and Silent pin?

If so, Why external pull up is needed on TXD pin and Silent pin when receiving open-drain output from AP/MCU?

  • 0
    TI__Mastermind 18940 points

    Hi Sunho,

    This is usually a consideration when there is a weak driving source for TXD/S or when the driving source is open-drain only. Most CAN controllers drive the TXD signal with a push/pull output and therefore do not need a pull-up resistor. You would configure the CAN TX output as open-drain only when you need to do level shifting, or to connect multiple transceivers. The reason for including external biasing resistor is to override the integrated bias if a different behavior is desired or to increase the signal's noise immunity by providing a stronger bias that will not be as easily modified by nearby coupled signals. 

    Regards,

    Sean