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DRV8350: Inquiry Regarding DRV8350RH VGS Jitter and Switching Period

Johnson David
Prodigy 110 points
Part Number: DRV8350

Tool/software:

Hello TI Team,

We have designed a 3-phase inverter circuit using the DRV8350RH IC.
We are controlling the MOSFET gates using the gate driver at a switching frequency of approximately 20 kHz.

When measuring the MOSFET VGS, we observed that the switching period continuously varies within the range of 19 kHz to 21 kHz.

We would like to know whether this is caused by dead time or by another factor.

Additionally, when measuring the VGS jitter, we found that the thickness of the positive and negative edges is approximately 2–3 µs.

We would like to know if this level of jitter is within a normal range.

Below is a schematic diagram of the VGS jitter for your reference.

Thank you.

Best regards,

  • 0
    TI__Expert 4445 points

    Hello,

    Thank you for reaching out.

    Can you make sure that input PWM is consistently 20k, and the variation is due to the driver not the inputs?

    The driver alone should not be causing 2-3us of jitter.

    if I could see waveforms to confirm that would help as well.

    Thank you,

    Joseph

  • 0 in reply to Joseph Ferri
    Prodigy 110 points

    Hello Joseph

    I found that this phenomenon is not jitter, but rather due to the fact that we are driving the motor with current control from the MCU, which adjusts the voltage level. As a result, the VGS period varies between 19 and 21 kHz.

    Thank you for your help.