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DRV8312 Adjusting PVDD for BEMF Compensation

Schlatte
Prodigy 20 points
Other Parts Discussed in Thread: DRV8312, TPS55340

Hi all,

I am wondering if I can increase the PVDD on my DRV8312 as my Motor Speed increases to compensate the BEMF and get higher RPM without losing torque.

Would that be a problem for the Protection Features of the IC? Or the Bootstrap Circuit or something? What would happen when I decrease the PVDD Voltage again? Could there be an overvoltage on the Bootstrap caps?

I want to use a TPS55340 in a Boost Topology to provide higher Motor Voltage after the motor has reached a certain speed.
So for starting up the Motor I'd use the normal Supply voltage directly from the PSU (high current, high torque, low speeds) and after the motor reaches a certain speed I'd switch to the boostet voltage from the TPS (less torque needed, lower current, more speed).

Best Regads,
Lucas

  • 0
    TI__Mastermind 21320 points

    Hi Lucas,

    I don't see any immediate issues with this scheme.

    The BST_X voltage is a floating voltage on the capacitor with respect to PVDD. So assuming you are only changing PVDD this should not be an issue. GVDD (supply for bootstrap) will remain fixed.

    You would need to ensure PVDD stays with in the operating region of the DRV8312 and I would recommend limiting the rate at which PVDD changes. 1 V/ms is a good target to stay far away from any ESD cell triggers or coupling in the system.