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DRV8343-Q1: diagnostic questions

Sherry Liang
Genius 10255 points
Part Number: DRV8343-Q1

Dear team,

My customer has some questions for the fault diagnostic, and they use our DRV8343-Q1 to drive BDC motor. Their register configuration is as below,

IC1 Control Register 0x04=0x40

IC2 Control Register 0x05=0x33

Questions:

1. OLA fault can't be reported. The mos they use is BUK9K29-100E, and Cphase needs to be larger than 1.86nF based on the formula in the datasheet, and they chose 10nF as below. Could you please help analyze the reason?

2. If the PWM duty cycle is smaller than 10%, the half bridge is shorting to battery, VDS_LA/B fault will be reported, but VDS_HA/B fault won't be reported if the half bridge is shorting to ground. Is this normal?

3. For Offline Shorts Diagnostics, if the customer use SPI version, do our device will run the short diagnostics at power-up?

4. The capacitance means Cphase?

5. For these fault diagnostics, do we have any demo code example?

Thanks & Best Regards,

Sherry

  • 0
    TI__Mastermind 23356 points

    Hey Sherry,

    I will aim to provide feedback next week, but there might be delay due to upcoming holidays.

    Best,

    Akshay

  • 0 in reply to Akshay Rajeev Menon
    TI__Mastermind 23356 points

    Hey Sherry,

     

    1. OLA fault can't be reported. The mos they use is BUK9K29-100E, and Cphase needs to be larger than 1.86nF based on the formula in the datasheet, and they chose 10nF as below. Could you please help analyze the reason?

    I see from the register settings provided that the OLA is enabled for phase A and B, so I just want to confirm that the motor is connected between those phases. The schematic is not very clear, so a pdf would be appreciated.

    Do you have a waveform of DLx-Vdrain and SLx-SHx to see if the voltage drop is exceeding the threshold needed to detect VOLA.

    How is the OLA being tested?

     

    1. If the PWM duty cycle is smaller than 10%, the half bridge is shorting to battery, VDS_LA/B fault will be reported, but VDS_HA/B fault won't be reported if the half bridge is shorting to ground. Is this normal?

    Is the following understanding correct?

    Short to battery:

    VDS_LA/B report but VDS_HA/B not reported.

    Short to ground:

    VDS_LA/B report but VDS_HA/B not reported.

    1. For Offline Shorts Diagnostics, if the customer use SPI version, do our device will run the short diagnostics at power-up?

    The device detects short-to-battery and short-to-ground conditions when the motor is not commutating. These offline diagnostics can be activated in the SPI device by setting the EN_SHT_TST bit high. Both the short-to-battery and short-to-ground diagnostics run when the EN_SHT_TST bit is set high.

    1. The capacitance means Cphase?

    The capacitance refers to the value of capacitor between motor phase pin to the ground.

     

    Best,

    Akshay