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DRV8308: VHSG signal is always in high state

Danilo A.
Mastermind 28680 points
Part Number: DRV8308

Hi Team,

We have received an inquiry from a customer that the VHSG of DRV8308 is always in a high state. The project is under prototype stage. Have you encountered a similar failure before? What could be the possible cause of the failure? I am still checking with the customer if we can post the schematic diagram here.

Regards,

Danilo

  • 0
    TI__Guru 65250 points

    Danilo,

    Thanks for posting on the MD forum!

    We would need the schematic and scope waveforms to confirm/debug the issue.

    I have not seen this before but sometimes customers confuse the high side gate being on when there is also the same voltage present at the switch node (Vgs is 0V in this case and the FET is OFF). The high side FET is ON when the gate voltage minus the switch node voltage is ~10V.

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    TI__Guru 65250 points

    Danilo,

    I have reviewed the schematic and I do not see any issues.

    Can you tell me exactly where the scope probe is placed in the schematic to measure the gate signals? Is the measurement single ended or differential to the switch node marked as "V" in the schematic?

    As a reminder the High Side FET VGS is measured as the difference between the high side gate (VHSG) and the source of the high side FET (V).

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    TI__Mastermind 28680 points

    Hi Adam,

    I am still waiting for the waveform measurement between the high side gate (VHSG) and the source of the high side FET (V) from the customer. For the meantime, the customer would like to ask for a list of common failure modes of DRV8308. 

    Regards,

    Danilo

  • 0 in reply to Danilo A.
    TI__Guru 65250 points

    Danilo,

    Please let us know when you have these plots.

    Unfortunately I cannot provide a list of "common failure modes" as I do not recall any common issues.

    Regards,

    -Adam

  • 0 in reply to Adam Sidelsky
    TI__Mastermind 28680 points

    Hi Adam,

    I have provided this link to the customer to post the information that you requested to help him resolved this issue. I will follow-up with him to reply in this thread.

    Thank you for your support.

    Regards,

    Danilo