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DRV8952: Current sensing in PGND connections

Henrik Nielsen
Prodigy 140 points
Part Number: DRV8952

Tool/software:

Hi TI-team.

We are planning on using the DRV8952 for a configurable high current digital output. This means that we would like to be able to drive either high side loads or low side loads on the device.

We will monitor the currents in the outputs, and in the data sheet it is stated that it is possible to use the PGND connections to monitor currents in the low side FET with a sense resistor. This solution is not very well described, even it looks straight forward. Has this been tested or do you know if this has been used successfully?

Can you elaborate on this solution?

 

If it was discrete MOSFETs, I would have not problem doing this. But with integrated devices everything inside is telling me this is wrong.

Looking forward to hear from you.

BR Henrik Buhl

  • +1
    TI__Mastermind 44685 points

    Hi Henrik,

    Thank you for posting in this forum.

    Henrik Nielsen said:

    This solution is not very well described, even it looks straight forward. Has this been tested or do you know if this has been used successfully?

    Can you elaborate on this solution?

    Yes this scheme works successfully. the RSENSE must be very small to minimize power loss as well as to keep the voltage drop across it to as low as possible - not to exceed 300 mV worst case. Keep it even lower, 100 mV or less. We don't want higher voltage drop which could affect the effective gate drive VGS voltage. 

    Also there is an absolute maximum negative voltage specification for PGND that must be considered. See below info from the datasheet.

     

    Other than these considerations this would be pretty much like you would do with discrete FETs low-side current sense. Thank you.

    Regards, Murugavel 

     

  • 0 in reply to Murugavel4637
    Prodigy 140 points

    Hi Murugavel

    Thanks for clarifying. I will take this into consideration.

    BR Henrik