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TCAN1145-Q1: What factors affect the Tsilence parameters? Temperature?

Guohai Lin
Expert 5311 points
Part Number: TCAN1145-Q1

Hi team，

The customer measured the wake-up time and found that the 1-second wake-up message cannot wake up the CAN chip. At room temperature, it can be awakened for 0.8 seconds.

Question 1 : What factors affect the Tsilence parameters?  Temperature?

Question 2:  Pls provide the corresponding curve or link formula between temperature and Tsilence . If it's only related to temperature.

Thanks!

  • 0
    TI__Guru 53555 points

    Hi Guohai,

    We do not have this data readily available. All timers are impacted by a variety of operating conditions including temperature, supply voltage, process variance, etc. We bound these specifications within datasheet parameters across all recommended operating conditions to guarantee that the behavior remains within the range specified. In the case of tSILENCE in the context of a WUF, the frame must appear within 0.6 seconds of the previous frame in order to be recognized by the selective wake receiver across all operating conditions. In a typical CAN system this is no problem because CAN controllers default configuration is to automatically retransmit any CAN frame that is not met with an acknowledgement. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott 

  • 0 in reply to Eric Schott1
    TI__Expert 5311 points

    Hi Eric,

    Thanks for your reply.

    The customer requires that the 1s cycle WUF must be used to wake up. How can we ensure that the customer's requirements are fulfilled?

    Thanks！

  • 0 in reply to Guohai Lin
    TI__Guru 53555 points

    Hi Guohai,

    If only a single frame is sent every 1 second, there is no way to guarantee that the second WUF will be recognized by the device before it moves back into "deep sleep" again. In order to ensure that the WUF is recognized while keeping the 1 second cycle, the cycle could be configured to send two frames (same WUF each time) each cycle. This would maintain to off-time of the very low active duty-cycle while guaranteeing that the WUF will be seen while the partial networking receiver is active. Would this solution be acceptable by the customer? 

    Regards, 
    Eric Schott  

  • 0 in reply to Eric Schott1
    TI__Expert 4010 points

    Hi Eric,

    Could you expand more about the two frames each cycle on "This would maintain to off-time of the very low active duty-cycle while guaranteeing that the WUF will be seen while the partial networking receiver is active" ? If you could share a timing diagram it would be very helpful!

    Thank you

    Scarlett

  • 0 in reply to Scarlett Cao
    TI__Guru 53555 points

    Hi Scarlett, 

    All I mean by this is instead of sending a single CAN frame every 1 second - send two CAN frames at the same time. I presume that the 1 second timing is meant to allow the processor to remain in a low power state for the whole time except when a frame needs to be sent. If the wake cycle to send the frame was extended to simply send two frames, this would have negligible impact on the system power consumption  while allowing two frames to appear on the bus within the 0.6 second window required by the TCAN1145. Is this description clear? Let me know if this is a possible solution  we may persue for this application. 

    Regards, 
    Eric Schott