• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 3 answers
  • Subscribers 33 subscribers
  • Views 359 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TCAN1043A-Q1: INH is low or high voltage level when remote up happen and UVnom happen in same time

lei.tian
Prodigy 30 points
Part Number: TCAN1043A-Q1
Other Parts Discussed in Thread: TCAN1043

Dear, sir

 In my use case when TCAN1043 is in sleep and VCC&VIO lost power in same time , the CAN bus have CAN message activity, so INH will pull to high level, but the UVnom of VCC&VIO will pull to low.

So my question, if both happen in same time, what the INH voltage level?

  • 0
    TI__Guru 53575 points

    Hi Letian,

    When the TCAN1043A enters Standby mode from Sleep mode, the UV timers are locked out until the supplies are detected to be above their undervoltage thresholds (UVcc and UVio). This means that if the undervoltage happens before the WUP is detected, there will be no impact on the transceiver - Standby mode will be entered and the device will remain in this mode until Vcc and Vio are active and the transceiver is driven into another mode using EN and nSTB (unless this condition persists for > tINACTIVE ~4 minutes). 
    In this case, the INH signal will be driven high when the WUP is detected and remain high until both supplies are stable. 

    If the device is in Standby mode (INH high) when Vcc or Vio falls below its undervoltage threshold (UV after WUP), the device will start the tUV undervoltage timer. When this ~100ms timer expires, the device will again check the status of the Vcc and Vio supplies. If there is still an undervoltage condition on one of these supplies, the device will enter Sleep mode and INH will be turned off. 
    In this case, INH will be high for at least 100ms before an undervoltage timeout can occur that will turn off INH again. 

    Let me know if this is clear and if you have any more questions.

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    Prodigy 30 points

    Hi,Sir

    My use case condition is during Vcc and Vio have no power supply, transceiver in sleep state, so during UVcc and UVio undervoltage thresholds condition, how to jude UV comming before or after WUP?

    As statement , during Vcc and Vio have no power supply, WUP is detected, but still have no Vcc and Vio supply, can we call it enter standby mode ?  are  the UV timers  locked out until the supplies are detected to be above their undervoltage thresholds (UVcc and UVio)?

  • 0 in reply to lei.tian
    TI__Guru 53575 points

    Hi Leitian,

    lei.tian said:
    are  the UV timers  locked out until the supplies are detected to be above their undervoltage thresholds (UVcc and UVio)?

    Yes. Vcc or Vio will need to be above their threshold and fall below the threshold in order to start the undervoltage timer. If Vcc and Vio are low before the WUP that causes the supplies to become active then there is no concern for the device starting the undervoltage timer.

    I hope this is clear. Let me know if there is anything else I can help clarify.

    Regards,
    Eric Schott 

  • 0 in reply to Eric Schott1
    Prodigy 30 points

    Hi, Sir

     I would like to ask if we have TCA1043 variant, which have no  this function ''When the TCAN1043A enters Standby mode from Sleep mode, the UV timers are locked out until the supplies are detected to be above their undervoltage thresholds (UVcc and UVio)'', my design is stuck here to lead to INH stuck H，it need rise edge to wake up power when VCC/VIO is in lost power.

  • 0 in reply to lei.tian
    TI__Guru 53575 points

    Hi Leitian

    When TCAN1043A is in Standby mode the SWE timer will begin to count. If the device does not enter normal mode within ~4 minutes then the device will automatically move to sleep mode and turn off the INH signal. Would this fail-safe feature be sufficient for your needs for this undervoltage case? 

    The TCAN1043 (non-A) does not have this undervoltage lockout feature and the undervoltage timers will begin to count immediately once standby mode is entered and the system will have ~160ms to bring these supplies up before the transceiver returns to sleep mode and INH is turned off. 
    I advise against using this device for new applications that do not require the +-70V bus fault protection feature. Future supply of this device will be limited as it is on an older process node. The TCAN1043A is on our latest process node and therefore offers our best supply capability and pricing. 

    Regards, 
    Eric Schott