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DRV8876: IC failure driven in high side configuration

Ivan Martinazzoli
Prodigy 60 points
Part Number: DRV8876

Hello,

 

I use DRV8876QPWPRQ1 for driving a bistable Electromagnet.

The driver is configured in Fixed Off-Time Current Chopping Mode with this setup:

  1. DRV8876 powered with 24Vdc

  2. PMODE and IMODE connected to GND

  3. VREF set to 2,5 Vdc

  4. VM connected with VCP with 100nF 50V capacitor

  5. VM connected to GND with a 100nF 50V capacitor

  6. CPH and CPL connected with 22nF 50V capacitor

  7. IPROPI connected with an resistor of 3,9kOhm to GND (Current limit fixed to 0,640mA)

For safety needs, I have to drive the power supply of DRV8876 with an external PMOS in high side configuration. So, first I activate the PMOS and the DRV8876 power on. After 50ms, I set the correct phase with in pin PH/IN2 and I active the PIN EN/IN1 (with single pulse no PWM) for 100ms and I see the bistable moving. I see the V_IPROPI and all is correct. Then, I reset EN/IN1 and after 50ms I deactivate the PMOS and DRV8876 power off.

But the problem is this: when I drive the DRV8876 repeatitively for many times with a period of 1s from an activation to another one as already explained above and I connect OUT1 and OUT2 for simulate a short-circuit to the OUTPUTs, the DRV8876 failure and then the FAULT pin is always low and the OUTPUT is always off.

Note: If the DRV8876 is always powered (VM always to +24Vdc fixed) and I simulate the short the DRV8876 work correctly and I see FAULT go low and OUTPUTs is off. When I remove the short, the FAULT pin come back high and output drive the ELM correctly.

I attempt your response.

 

Thank you.

Ivan

  • 0
    TI__Mastermind 37683 points

    Hi Ivan,

    I want to clarify your question to make sure I understand correctly. Is the device not working and nFAULT pin stays low even after disconnecting the short and re-enabling the power to the device? Is my understanding correctly?

    When shorting the outputs and enabling the power to the driver, the device will trigger an OCP fault causing the nFAULT to drop LOW and the outputs disabled. If after 2ms, the short is still present, the outputs will continue to remain disabled until the short is remove. If you removed the short between OUT1 and OUT2 and the fault is not removed withing the end of the 1s activation cycle, then we'll have to take a closer look because that should not occur.

    When power is always provided to the driver and the short is removed, it is expected for the device to self-recover and resume operation.

    Can you provide a waveform of the power supply and nFAULT for multiple power cycles.

  • 0 in reply to Pablo Armet
    TI__Mastermind 37683 points

    Hi Ivan,

    Were you able to fix your issue?

  • 0 in reply to Pablo Armet
    Prodigy 60 points

    Hi Pablo,

    Unfortunately I was no longer able to replicate the problem.

    I think at this point it was an ESD problem.

    Thank you for the support.

    Regards,

    Ivan

  • 0 in reply to Ivan Martinazzoli
    TI__Mastermind 37683 points

    Hi Ivan,

    Thank you for the update.

    In that case, I will close this thread. If you need further support, you may reply to this thread. If the thread is locked, you can ask a new related question.