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Original question:

Compiler/TCAN1043-Q1: tcan1043-q1

TCAN1043-Q1: CAN timing

luo sui
Prodigy 70 points
Part Number: TCAN1043-Q1
Other Parts Discussed in Thread: TCAN1043

Tool/software:

HI all：请问TCAN1043的tpower_up是指Vsup=4.5V到INH=Vsup-1V=11V的这段时间吗？我实际测量我们产品的Vsup=11.6V，INH=9.8V，这种情况下，tpower_up如何界定？谢谢

  • 0
    TI__Genius 13402 points

    Hi Luo,

    To clarify, I believe you are asking how the time tPower_Up is defined. You measured VSUP to be 11.6V and INH to be 9.8V. 

    The time tPower_Up is defined as the time it takes for INH to reach a logic high after VSUP is greater than the undervoltage threshold (4.5V). 

    Let me know if that answers your questions or if you have more questions.

    Regards,

    Ethan

  • 0 in reply to Ethan Sempsrott
    Prodigy 70 points

    Hi Ethan，

    请问INH to reach a logic high如何界定，是指INH到达TCAN1043的3号引脚VCC供电的0.7倍以上吗，谢谢

  • +1 in reply to luo sui
    TI__Genius 13402 points

    Hi Luo,

    The INH pin is connected to the VSUP line with a diode to protect the INH line. This diode voltage drop should be about 0.5V - 1V so INH should be about 1V less than VSUP. 

    So in your situation, if the VSUP is 11.6V then INH ideally should be 10.6V. However, you likely have components on your INH line that could be affecting this. The exact INH voltage should not affect the operation of the system as long as it is a clear logic high for other downstream devices. 

    Regards.

    Ethan

  • 0 in reply to Ethan Sempsrott
    Prodigy 70 points

    Hi Ethan, 

    你提到的a clear logic high for other downstream devices，假设TCAN1043的INH引脚接到了一颗DCDC的使能引脚，这颗DCDC使能引脚的逻辑高电平是5V，这时是否可以理解为INH达到5V就是高电平？谢谢

    best regards

  • +1 in reply to luo sui
    TI__Genius 13402 points

    Hi Luo,

    That is correct, the INH pin is typically connected to the enable pin of a DCDC converter. Your INH pin voltage will satisfy the logic high for 5V, assuming the DCDC EN pin supports voltages this high.

    Regards,

    Ethan

  • 0 in reply to Ethan Sempsrott
    Prodigy 70 points

    Thanks，Ethan，你的回答解决了我的疑问

    best regards