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Original question:

DRV8353RS-EVM: DRV8353RSRGZT - VGLS and Charge Pump Voltage is not working, High Side and Low Side Gate MOSFETs aren't getting...

DRV8353RS-EVM: DRV8353RSRGZT - Hardware Control and SPI Fault Register Access

Divya Tarana
Prodigy 50 points
Part Number: DRV8353RS-EVM

Hi 

I'm using DRV8353RS Gate Driver for BLDC Motor Control. I'm sending the PWM Control Signals through Hardware (Directly on INHX Pins while SPI is disabled) but would like to access Fault Status registers through SPI. I want to access the registers since I'm getting a Gate Fault only when trying to load the Motor with 100% Duty.

Can someone suggest if it's feasible? Or any diagnosis for Gate Fault Indication during 100% Duty? 

Thanks & Regards

Divya

  • 0
    TI__Mastermind 26046 points

    Hi Divya,

    What do you mean when SPI is disabled? Is the DRV8353RS still powered on and enabled when applying PWM inputs?

    When the motor is loaded with 100% duty, GHx should always be on and GLx should always be off for the phase driving the motor. Can you ensure that GHx stays on and GLx stays off when monitoring the gate drive waveforms?

    A gate drive fault is detected if the FET is not "on" or "off" by the end of the TDRIVE time. The IDRIVE settings are applied for TDRIVE to turn on/off the MOSFET gate. If IDRIVE settings are too small or TDRIVE is too high, then a gate drive fault might occur. 

    Can you use a higher IDRIVE value or a lower TDRIVE time to see if the faults still occur?

    Thanks,
    Aaron

  • 0 in reply to Aaron Barrera
    Prodigy 50 points

    Hi Aaron 

    I'm not using SPI Communication (nSCS = 1). But I would like to access Fault Status Registers. 

    When Motor is loaded with 100% Duty, GHx is ON and GLx is OFF (Trapezoidal Commutation). The PWM Pulses are as desired till 100% Duty. Phase - Phase. Phase - Ground Voltages are as desired till 95% Duty. If I increase the Duty beyond 96-100%, there's Gate Driver Fault. ( I would like to know which protection feature is being enabled at this point). 

    Right now, the IDRIVE and TDRIVE Setting are as per Default. ( TDRIVE = 4000 ns, IDRIVEP = 1000 mA, IDRIVEN = 2000 m A) 

    Thanks & Regards

    Divya 

  • 0 in reply to Divya Tarana
    TI__Mastermind 26046 points

    Hi Divya,

    Please reduce the IDRIVE settings to lower settings. Using the default IDRIVE settings (IDRIVEP = 1000 mA, IDRIVEN = 2000 mA) is too high of an IDRIVE current for the EVM as you will be switching on the MOSFETs too quickly and causing abnormal gate drive behavior (ringing, coupling, transients, etc.).

    Please try the 150mA/300mA settings to see if this improves your motor operation.

    Thanks,
    Aaron