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DRV8243-Q1: diagnostic logic

Mingkang Song
Expert 3360 points
Part Number: DRV8243-Q1

Hi,

When running in PH/EN mode, do the following faults comply with the chip's own diagnostic logic?
1. Forward rotation, EN=20%duty, OUT2 short to ground, chip reports H2_OCP fault;
2. Reverse rotation, EN=20%duty, OUT1 short to ground, chip reports H1_OCP fault;

Thanks!

  • 0
    TI__Mastermind 45265 points

    Hi Mingkang, 

    May I know what is the concern with the observation? A short to GND on OUTx will result with over current via the conducting HS-FETs. So a global OCP along with the corresponding HS-FET OCP fault, either H1_OCP or H2_OCP fault as qualifiers will be reported in the SPI control devices.

    Regards, Murugavel

  • 0 in reply to Murugavel4637
    TI__Expert 3360 points

    Yes, you're right.  Will the observation be the same under the condition of EN=20%duty?

  • +1 in reply to Mingkang Song
    TI__Mastermind 45265 points

    Hi Mingkang, 

    Yes. Technically it should be the same. When the short happens while there is current recirculation (high-side) during PWM off time the motor could change direction depending on which OUTx was energized and which OUTx was shorted. This may complicate behavior. But in general the HS-FET OCP fault will occur for a OUTx to GND short even with 20% or lower PWM duty cycle. You can test this with an EVM. 

    Regards, Murugavel