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DRV8872: DRV8872-Q1 short to power supply protection

Michael Huang3
Intellectual 2460 points
Part Number: DRV8872

Hi team,

My customer wants to know if DRV8872 has short-to-supply protection? What will happen when the part's output is connected to VM? VM is 24-36V.

They feedback when they put PH to the power supply, the system's total current consumption will add 30mA. Is it a DRV8872's normal behavior? 

Regards

Michael

FAE

  • 0
    TI__Guru** 114905 points
    Hi Michael,

    The DRV8872-Q1 does have short to supply or ground protection on the outputs. If an output is short to VM and enabled low, or an output is short to GND and enabled high, an overcurrent event will occur.

    The nFAULT pin should signal a fault and the output will re-enable after approximately 3ms.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Michael,

    For the second part, yes this is normal. There are internal paths protecting the Vgs of the high side.
  • 0 in reply to Rick Duncan
    TI__Intellectual 2460 points
    Duncan,

    Thanks for your reply.
    So the current 30mA is reasonable because it flows into PH pins to Vgs Zenar diode inside?

    Another question. You said when short to VM with enable low, and short to GND with enable high. What about the condition short to GND with enable low, and short to VM with enable high? Will it report any fault. In my understanding it will not report a fault, because there is no current going into PH. Is it right?

    Regards
    Michael
  • 0 in reply to Michael Huang3
    TI__Guru** 114905 points
    Hi Michael,

    I was not clear.

    "If an output is short to VM and enabled low, or an output is short to GND and enabled high, an overcurrent event will occur." In both cases, the outputs are enabled. A fault is reported.

    "output shorted to VM and enabled low" means the IN1/IN2 inputs are set to Reverse, Forward, or Brake. OUT1 or OUT2 should be driven low but is shorted to VM. An overcurrent event will occur.

    "output shorted to GND and enabled high" means the IN1/IN2 inputs are set to Reverse or Forward. OUT1 or OUT2 should be driven high but is shorted to GND. An overcurrent event will occur.

    You mentioned enable and PH. Please confirm you are asking about the DRV8872-Q1.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Michael,

    I have not heard back from you in some time, and am assuming your questions were answered.

    If they were not, please reply to this post or open a new one if the post is locked.
  • 0 in reply to Rick Duncan
    TI__Intellectual 2460 points

    Hi Rick,

    I sent you a mail about the further support:

    Customer can't understand very clearly where the 30mA go when OUT is connected to VIN. Could you please draw a brief diagram to show the 30mA current path inside the DRV8872 when short to VIN?

    Regards

    Michael

  • 0 in reply to Michael Huang3
    TI__Intellectual 2460 points
    Hi Rick,

    I didn't recieve your reply online or offline. Could you kindly check and help?
    Thanks for your support.

    Michael