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Original question:

TCAN4551-Q1: Two questions about the TCAN4551-Q1.

TCAN4551-Q1: Two questions about TCAN4551-Q1 (why the standby mode time is 4 minutes, wake up due to noise rather than WUP)

byunghee jeong
Prodigy 20 points
Part Number: TCAN4551-Q1

1. Why was 4 minutes of standby mode set during the design stage?

2. This is to test waking up from Sleep Mode when there is noise in CAN.

When a voltage other than WUP is applied to CAN, it is necessary to check whether sleep mode is maintained.
(Or you need to check the conditions for waking up from Sleep mode)

Is it possible to wake up with a noise component other than WUP?

  • 0
    TI__Guru 50745 points

    Hi Byunghee,

    Thanks for bringing your questions to E2E.

    byunghee jeong said:
    1. Why was 4 minutes of standby mode set during the design stage?

    The TCAN4551 has a failsafe feature that automatically puts the device into sleep mode if it has stayed in standby mode for ~4 minutes. Because standby mode is designed to be a transitional mode to allow the MCU to start up after the system was in a sleep state, it is assumed that if the transceiver remains here for this long that some fault has prevented the MCU from moving the device to some other mode. Therefore the transceiver will move to its lowest power state to minimize the power impact on the system of this presumed faulty node. You can read more about this feature and how the configure it in section 8.4.5 for the datasheet. 

    byunghee jeong said:
    Is it possible to wake up with a noise component other than WUP?

    The WUP has been defined to filter out differential noise by having minimum hold-times for the dominant and recessive states of the pattern. This will allow the low power receiver to ignore many glitches that may appear on the bus during sleep mode. It is theoretically possible that noise could generate the correct conditions for a WUP on the bus and cause a CAN device to wake up, though this scenario is unlikely in most systems. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott 

  • 0 in reply to Eric Schott1
    Prodigy 20 points

    Hello! Thank you for your answer to the previous question.

    Do you know why the standby mode was designed for 4 minutes instead of 1 or 2 minutes?

    Regards, 

  • 0 in reply to byunghee jeong
    TI__Guru 67572 points

    Byunghee,

    I'm not sure we have a great answer other than feedback from customers came to a consensus that 4 minutes was an optimal time.

    Regards,

    Eric Hackett