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  • TI Thinks Resolved

DRV8353: DRV8353RS Buck converter not starting

Prodigy 20 points

Replies: 5

Views: 240

Part Number: DRV8353

Hi ,

I am testing my new hardware with DRV8353RS. I supplied it with 20V.

Schematic of DRV8353RS connection:

When I connect 20V to +UBat, i am waiting for 5.3V at output, but there is 0.5V without loading. If i load output to 100 OHM, there is 0V.

The following signals are present at the buck converter pins:

- SW: short  50kHz pulses:

- VIN: DC 20V

- VCC: DC 7V

- BST: some 50kHz pulses with 7V level:

  

- RCL: DC 0.2V

- RT/SD: DC 2V

- FB: DC 0.2V

- Current consumption ~50mA, DRV8353RS heats up.

  • Vyacheslav,

    The buck regulator inside the DRV8353 is the LM5008A device. I will move your post to the power group.

    Regards,

    -Adam
  • In reply to Adam Sidelsky:

    Ok, do it, please. Thanks!
  • In reply to Vyacheslav Kulakov:

    Vyacheslav,

    We will get someone to look into this. Probably on Monday.

    Best  Regards,

    John Tucker

    BSR-CCP LV/MV DC/DC Applications

  • Hello Vyacheslav,

    Can you share the schematic of the LM5008?  

    Thanks.

    David.

    Kind Regards,

    David Baba.

  • In reply to David Baba:

    Hello Vyacheslav

    I was notified that the LM5008A is integrated in the device in question.  I reviewed the schematic and waveform above.  One thing that jumps out at me is that the switch node waveforms provided,  only show switching to a few volts with 20V in?  If so, it suggests one of two things.

    Either the input voltage is dropping, or the device is damaged, i.e. high RDSon when switching?

    Please check input supply, if present (20V), then I would replace device.

    Hope this helps?

    David.

    Kind Regards,

    David Baba.

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