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DRV8353RS-EVM: Negative pressure on the SPx/SLx side

Annie Liu
Genius 10295 points
Part Number: DRV8353RS-EVM

Hi Team,

Board: 48V power supply, using DRV8353RS driver.

When switching, especially when the power is turned off, the measured SPA, SPB, and SPC terminal voltages appear large negative voltages, which are already greater than the normal value of -5V. 

Three-phase bridge circuit:

Two negative pressure situations appearing on the SPx side:

  

Thanks,

Annie

  • 0
    TI__Mastermind 21805 points

    Hi Annie,

    What "power" is turned OFF? The DRV835x should not be able to switch if the power supply is disabled.

    What IDRIVE setting is being used and what is the MOSFET part number? I think IDRIVE may be set too high.

    Please have the customer review this IDRIVE FAQ: LINK

    Thanks,

    Matt

  • 0 in reply to Matt Hein
    TI__Genius 10295 points

    Hi Matt,

    Power off means that the motor "brakes" (so that the motor speed will be 0). The customer controls the motor to start and stop repeatedly, there will be a large negative pressure, between -6~-7.4V.

    IDRIVE is set to 60, 120mA; MOS is: csd19533, Qgd=4.9nC;

    Thanks,

    Annie

  • 0 in reply to Annie Liu
    TI__Mastermind 21805 points

    Hi Annie,

    With a hard brake the motor current will increase to a very high current, and that will result in higher negative and positive voltage spikes when switching the MOSFETs ON and OFF. Please note that when operating at higher currents, we expect negative and positive voltage spikes to increase.

    You may need to reduce the IDRIVE to a lower setting. Generally a lower IDRIVE results in less transient voltage spiking. The customer can use a lower IDRIVE setting or add a series resistor externally to further reduce the gate drive current.

    Thanks,

    Matt