• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 33 subscribers
  • Views 459 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCAN1042-Q1 Way to Completely Disable the Transceiver

Shinichi Yokota
Genius 9715 points
Other Parts Discussed in Thread: TCAN1042-Q1

Hello,

I'm looking for a way to completely disable the CAN transceiver TCAN1042-Q1. Here "completely disable" means, the device won't wake up an external MCU by WUP (Wake Up Pattern) AND the device won't transmit a signal from the MCU onto CAN bus.

  • As long as the transceiver stays in standby mode by enabling its STB pin, the TXD pin won't accept any signal.
    • Idea 1: If a gate logic is placed between the RXD pin and the MCU, I guess it can block a signal triggered by WUP. But, will it activate the transceiver too and will a signal on the TXD pin be transmitted onto the CAN bus?
    • Idea 2: V-suffix versions integrate a level shifter. If a VIO pin is tied to GND, will it prevent a signal triggered by WUP from coming out from the RXD pin? If yes, is there any possible current leakage path between VIO and VCC pins when the VIO is at GND while the VCC is on?

Any other ideas?

Best regards,
Shinichi Yokota

  • 0
    TI__Prodigy 200 points
    Hello Yokota-san,

    Both of your ideas will work.

    Idea 1: As long as the part is in standby mode by enabling the STB pin, the transmitter will remain off regardless of what the TXD and RXD pins do. At that point it will just be a matter of inserting a logic gate between the RXD pin and the MCU. For example you could put a two input OR gate with RXD as one input and STB as the second input and then whenever STB pin is logic high the RXD signal to the MCU will also be logic high.

    Idea 2: This will also work. According to Table 3 in the datasheet if VIO is powered down while VCC remains powered up the part will be in protected mode and the RXD output will be high impedance, even if a WUP pattern appears on the CAN bus. There should not be any leakage paths between VIO and VCC, so having VIO at GND while VCC is on should be perfectly okay.

    Best Regards,
    Richard