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TPS56C215: TPS56C215 / Current limit hiccup mode behavior

S.Satoshi
Guru 21685 points
Part Number: TPS56C215

Hi,

I evaluate EVM to see current limit behavior as attached. Then please let me ask about this behavior.

  1. Regarding duration 1, how is this duration is estimated? Please let me know the maximum duration from current limit detected to first retry.
  2. Regarding duration 2, it looks this duration is fixed continuously. Can you please how to calculate this duration?

Best Regards,

Satoshi / Japan Disty

  • 0
    TI__Expert 5745 points

    It seems the DS is not very clear about the Hiccup, i'll double check with designer and give you respond as soon as possible.

  • 0 in reply to Vental Mao
    Guru 21685 points
    Hi, Mao,

    It will be very helpful. I'm waiting for your update.

    Best Regards,
    Satoshi
  • 0 in reply to S.Satoshi
    TI__Expert 3480 points
    1. How did you do OC, can you draw your short point in the waveforms? In your waveforms, why Iout is higher before duration 1?
    2. What's your target Vo? What's your load before duration 1? What's your load after duration 1?

    Pls describe question in detail. If you just upload a waveform and let us explain, we don't know anything.
  • 0 in reply to Gavin Wang (Zejing)
    Guru 21685 points

    Hi Wang,

    Here is information for your question.

    • Load is electrical load with CC mode
    • Iout is measured before electrical load
    • Vout is measured at TP9
    • Vout setting is 1.0V from 5.0V input
    • Frequency setting is 1.2MHz

    Please let me know if you need more information though this can be seen easily by using EVM.

    Best Regards,

    Satoshi

  • 0
    TI__Expert 5745 points

    When the OCP, it will trigger the UVP and shuts down the device after a wait time of 1 * Tss, the device re-starts after a hiccup time of seven cycle Tss. So the duration 2 is equal to 7*Tss and the following duration is also equal 7 * Tss

    For the duration 1, it actually miss counts the SS time since SS voltage takes time to discharge from VDD5 voltage to gnd. It doesn’t affect hiccup operation as long as the second delay matches  7 x Tss

  • 0 in reply to Vental Mao
    Guru 21685 points
    Hi Mao,

    I'm very sorry but I forgot that I changed Css from default value 0.047uF to 0.1uF when I measured this waveform. In case of Css=0.1uF, the calculated tss will be 10ms, then is this these duration reasonable result?

    Best Regards,
    Satoshi
  • 0 in reply to S.Satoshi
    TI__Expert 5745 points
    when the Css=0.1uF, it doesn't means the Tss=10ms, you need to measure the actual waveform. Because the value of the cap will be changed in different voltage.The calculated 10ms is just a reference.
  • 0 in reply to S.Satoshi
    Guru 21685 points
    Hi Mao,

    Can you kindly check the this hiccup behavior with Css=0.1uF on your bench?

    Best Regards,
    Satoshi