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DRV8847: DRV8847 break down due to induced EMF

Yang Wu
Expert 3330 points
Part Number: DRV8847

Hi Team,

My customer has a issue as below: 

1. DRV8847 is used to drive a BDC and two air valve with independent H bridge as below.

2. When the system was power-off, using hand to rotate the BDC, it got 35V peak induced EMF and the device broke down (VM-GND impedance is 0) . test points were OUT1/OUT2 - GND, waveform as below.

3. so the question is does OUT1/OUT2 can only sustain maximum voltage @ 18V (which is the max stress of the power supply)? How we can solve this issue? 

Thanks a lot

Yang

  • 0
    TI__Guru 56650 points
    Yang,

    Datasheet "6.1 Absolute Maximum Ratings" section lists the OUTx pin maximum voltage rating. It is connected VM pin through the internal FET's body diode. VM pin has 20V absolute maximum rating. As you said, using hand to rotate the BDC, it got 35V peak induced EMF and the device broke down. So, the part got damage.

    To resolve this issue, we have to absorb that energy. A TVS (Transient Voltage Suppressor) diode on VM pin could be a solution.
  • 0 in reply to Wang5577
    TI__Expert 3330 points
    Hi Li,

    Thanks for your reply.