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Original question:

DRV8812: OCP time

DRV8812: DRV8812 OCP and Current Regulation Function

Kazuki Kitajima
Intellectual 1480 points
Part Number: DRV8812

Hi team,

I'd like to confirm 3 things relating to OCP function and current regulation.

1. If the current is over I_OCP value, it should be limited internally. Then when it continues 3.0us(refer to the URL), OCP function should work. Is this correct?

2. Following #1, would you mind sharing the internal current limit value?

3. According to the DS, "Once the current hits the current chopping threshold, the bridge disables the current until the beginning of the next PWM cycle."

    If the current is over I_CHOP, the function works until the current is under I_CHOP meaning the bridge could disable the current several cycles. Is this correct?

Thank you,

  • 0
    TI__Intellectual 1480 points

    Apologies for keep asking, but could you tell me one more thing below?

    4) In datasheet p5, "Peak motor drive output current, t < 1 μS: internally limited". What does "t < 1 μS" mean? Assuming that the internal analog limit works only under t < 1 us, then what about between 1us to 3us?

    Thank you,

    Kazuki Kitajima

  • 0 in reply to Kazuki Kitajima
    TI__Mastermind 37683 points

    Hello,

    1) Yes that is correct

    2) The internal current limit value is not fixed but rather varies. 

    3) No, once the current is above the I_chop threshold, the bridge disables the current until the start of the next PWM cycle. 

    4)The t<1us is the maximum time the peak motor drive output current can go through the outputs. The internal analog limit circuit limits the current to a level that does not cause damaged to the FETs  if t<1us.