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DRV8353: Unused phase connections

Mark Guastaferro
Genius 11645 points
Part Number: DRV8353

My customer has a DRV8353S eval set-up and would like to use only two of the half-bridges. How should he tie off the unused phase pins?

Assuming Phase C is unused. My thought is to pull INHC and INLC low to turn off FETs and place SHC in Hi-Z state.

On the driver outputs: tie GLC to SPC and tie GHC to SHC. Keep Rsense on SPC to pull down to ground. Would it also be a good idea to tie a resistor from SHC to ground to drain any leakage current?  If so, what value? Would there be any protection circuits that would be impacted by SHC pull down?  (SHC is not tied to any motor node)

  • 0
    TI__Guru 65190 points

    Mark,

    In general for an unused phase on the DRV835x we recommend the following:

    Gates should be floating.

    PWM inputs have internal pull downs so they can be left Hi-Z from the MCU or pulled low.

    SHx should be tied to GND.

    If GH and GL are OFF, they will already be connected to their respective source connections so nothing additional needed there.

    Short the sense resistor to make sure that SP and SN are always at the same potential and grounded.

    I would remove the FETs on the unused phase if using the EVM.

    There should be no issue using the other two phases as normal.

    Regards,

    -Adam