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LP8861-Q1: OCP & VBOOST Output Short to GND

hideyuki sakai
Mastermind 6250 points
Part Number: LP8861-Q1

Dear, Sir.

My customer is requesting to explain the detail of feature on LP8861-Q1.

I would like to make sure the behavior of LP8861-Q1 under VBOOST output short to GND.

Below is my underding, Please give your advice, correct or not.

1. OCP is the fuction to monitor the internal Boost FET by current sense.

    Bsically, it can measure only Boost FET ON.

2. If VBOOST output was shorted to GND.

    OCP is not activated because of above 1), Boost itself continue to work.

3. LP8861-Q1 has the fuction to control for the external Power-line FET.

    If VBOOST output was shorted to GND, the FET will turn OFF to protect the

    circuit. It is a kind of feature.

Best Regards,

H. Sakai

  • 0
    TI__Expert 4565 points

    Hi Sakai-san,

    Your understanding is correct basically.

    LP8861-Q1 doesn't support boost OCP fault, so FAULT signal is not generated and power line FET still works during boost OCP condition, while boost still monitors SW current and limits it by SW control(turn off internal FET when boost OCP condition happens, not power line FET).

    When boost out and GND is shorted, Vin OCP fault will be triggered within ~10us after overcurrent is detected at input sense resistor and disconnect power line FET. So, boost OCP condition will be also solved almost immediately.

    Hope this helps,