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DRV8312: Reset signal and FOC clarification

LM
Prodigy 40 points
Part Number: DRV8312
Other Parts Discussed in Thread: MOTORWARE

I'm porting a successfully working FOC based design (custom hardware and software) to using a DRV8312 with the same custom software, and I'm having a bit of trouble.

Can I please get a clarification on the requirement to drive the RESET_X pins when using FOC based control.

I previously used complementary PWM signals to drive the high and low FETs. With DRV8312 is it necessary to drive the RESET_X pins with PWM, or only to hold them high and drive the PWM_X pins.

I note that motorware HAL for DRV8312 KIT configures the RESET_X pins to use PWM (with PWM_DeadBandOutputMode_Bypass configured) so that the RESET_X PWM signals are not inverted. This has confused me! Is this necessary to do?

  • 0
    TI__Mastermind 26766 points

    Hi Laurence,

    Thank you for your question! 

    The RESET_X pins determine whether the corresponding phase is Hi-Z or not. If RESET_X is 0, then the MOSFETs of the corresponding phase will be Hi-Z. If RESET_X is 1, then the corresponding phase is enabled and the PWM_X input will determine whether the high side or the low side FET will be on. Typically for FOC, since all 3 phases will have 1 FET on at all times, you will want to keep the RESET_X signals high and control which MOSFET is on using the PWM_X inputs. The only time RESET_X should be low is if you want a phase to be in Hi-Z state (both FETs off). 

    I am not a coding expert, but it think that the motorware HAL is implementing a fancy way of keeping the RESET_X signals high. You could even use a simple GPIO output to hold the RESET_X signals high. 

    Regards,

    Anthony Lodi

  • 0 in reply to Anthony Lodi
    Prodigy 40 points

    Hi Anthony,

    This is the same conclusion I have come to. Things seem to be working well now.

    Thanks very much for your clarification.

    Laurence M