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TCAN1043G-Q1: TCAN1043 wake-up function enable by ESD test (ISO-10605)

Hsin Bruce
Prodigy 130 points
Part Number: TCAN1043G-Q1
Other Parts Discussed in Thread: TCAN1043, STRIKE, TCAN1043-Q1

Hi TI member,

Regarding the CAN wake-up function,

When do ESD discharge(± 4/6/8/15kV, ISO-10605) on CAN bus whatever contact and air. We found the ESD will cause the TCAN1043 trigger the INH lead to DUT wake-up.

Because the ESD clamping waveform will similar wake-up pattern(high -> low -> high) of TCAN1043. Interestingly, it will trigger when the negative current is on CAN_L, or the positive  current is on CAN_H

 

Is the wake-up pattern can be adjusted? (ex. Increase the recognition of CAN device ID) 

And do you have any suggest about this situation?

Thank you.

PS. CAN bus ESD protection diode is PESD1CAN-U.

Best Regards

Bruce Hsin

  • 0
    TI__Guru 70432 points

    Bruce,

    Thanks for bringing this to our attention, glad you are using the TCAN1043-Q1. Unfortunately no, the CAN bus wake-up pattern (WUP) is defined by the ISO11898-2:2016 specification, so it is not adjustable. The ESD protection diode you are using is also a good device for protecting the CAN bus, and filter capacitors may be helpful in filtering out some of the ESD strike, but waking the device through the CAN bus on an ESD strike may be unavoidable.

    Is this a test that the device must pass for your application?

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 130 points

    Hi Eric,

    Thanks for your reply. 

    Yes, For our application, customers want to know if this is normal?

    As your experience, do you know another application or product have this situation? And those RD how do solve the problem of wake-up??

    Thanks a lot.

    Best Regards

    Bruce Hsin

  • 0 in reply to Hsin Bruce
    Prodigy 130 points

    Hi Eric,

    Do you have any suggestions for above question?

    Another questions. we have detail to check Spec of TCAN1043. The wake-up (High/Low keep time) timing is about 0.5us ~ 1.8us.

    But the waveform of ESD dischatge High/Low keep time is less than 10ns. Why it can trigger the INH function?

    Thanks a lot.

    Best Regards

    Bruce Hsin

  • 0 in reply to Hsin Bruce
    Prodigy 130 points

    Hi Eric,

    Sorry, Add second questions. we tried to monitor pin "nFAULT" to confirm the wake-up status. When transceiver wake-up by voltage discharge or "wake" pin enable. The flag of WAKESR will keep "LOW". if use the CAN bus activity that validates the WUP requirements. The flag of WAKESR will keep "High".


    we want to know why the voltage discharge on CAN_H or CAN_L bus the CAN transceiver is judge the action are state change on WAKE terminal ?
    Thank you.

    Best Regards

    Bruce Hsin

  • 0 in reply to Hsin Bruce
    TI__Guru 70432 points

    Bruce,

    As part of certification testing, all ESD testing is performed while the device is unpowered, or powered on and communicating. So we have no requirement for the device to stay in sleep mode during an ESD event, and I haven't tested this myself. The majority of applications are more concerned with protecting the transceiver through an ESD event rather than just waking it up. 

    I'm curious if rather than waking the device through CAN bus wake-up, if for some reason the device is going through a POR event because VCC or VIO or VSUP are dipping low when the ESD strike occurs.

    I'm not sure I understand the second question, so when CANH or CANL discharges the nFAULT pin stays low? Upon entering normal mode, the wake source can be indicated through the nFAULT pin. A low represents local wake, and a high represents CAN bus wake-up.

    Is it possible to go into silent mode after an ESD strike occurs and the INH is high (the device is in standby mode)? I'm curious if the PWRON flag is getting set.

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 130 points

    Hi Eric,

    Bother you again,  Regarding the nFAULT pin are confirmed when CANH or CANL discharges the nFAULT pin will pull high.

    But we are still looking for why ESD will cause CAN transceiver to be awakened(because other vendor transceiver will not happen).

    We try to use the external 12V to contact the CAN_H to simulate WUP. but even an incomplete wake pattern can trigger INH too.

    Do you have any suggestions regarding this phenomenon? 

    Best Regards

    Bruce Hsin

  • 0 in reply to Eric Hackett
    Prodigy 130 points

    Hi Eric,

    Bother you again,  Regarding the nFAULT pin are confirmed when CANH or CANL discharges the nFAULT pin will pull high.

    But we are still looking for why ESD will cause CAN transceiver to be awakened(because other vendor transceiver will not happen).

    We try to use the external 12V to contact the CAN_H to simulate WUP. but even an incomplete wake pattern can trigger INH too.

    Do you have any suggestions regarding this phenomenon? 

    Best Regards

    Bruce Hsin

  • 0 in reply to Hsin Bruce
    TI__Guru 70432 points

    Bruce,

    For the 12V to CANH test, is it possible to increase the time resolution (less time per division) to fully capture the second rising edge? Since the threshold for a dominant bit is only a 0.9V differential, and the time resolution is fairly low, it's possible that the differential actually meets the filtered dominant timing threshold for the device to see the full WUP.

    In your previous posts, you shared images but they didn't post correctly. Was one of them a capture of the ESD waveform waking up the device? Is it possible to share this? There may be an averaging affect happening in our wake receiver circuit because of the bandwidth being limited, and because there's an indeterminate range (between 0.5 and 0.9V) on CAN receivers for dominant and recessive, if the voltage is held here for an extended period of time, the receiver may interpret as dominant in the higher end of the range and recessive in the lower end of the range. 

    When you say the nFAULT pin will go high, do you mean when the device transitions to normal mode after the wakeup?

    Regards,

  • 0 in reply to Eric Hackett
    Prodigy 130 points

    Hi Eric,

    Thanks for your reply. Yes, the device transitions to normal mode after the wake-up.
    Our design is through the "INH" connect to MCU(for PWR control) to enable all power.

    I previous capture just a ISO-10605 ESD waveform. Mainly want to ask ESD is a change in nanosecond, why can trigger the WUP of 0.5 us~1.8 us?
    We haven't the high voltage probe can to measure the waveform of ESD on CAN bus. This is also one of the reasons can't to confirm why ESD waveform will equal WUP.

    But we have try other vender transceiver(NXP and Infineon), it can't be awakened by ESD.

    Thank you

    Best Regards
    Bruce Hsin

  • 0 in reply to Hsin Bruce
    TI__Guru 70432 points

    Bruce,

    What may be happening is the ESD strike is causing the CANH and CANL waveforms to be in an indeterminate threshold zone (between 0.5V and 0.9V) so that the receiver can interpret either a dominant or recessive. I agree that due to the timing of the ESD waveform, I'm not sure this makes sense though. Without waveform captures of the CAN bus during the strike, this will be difficult to understand though.

    With the Infineon and NXP devices, are the test boards and procedures the exact same?

    Regards,