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DRV8873HEVM: Fault pulled low

Cherry Zhou
Mastermind 22235 points
Part Number: DRV8873HEVM

Hi team,

Here's an issue from the customer may need your help:

The DRV8873HPWPR is driving a push-bar (brushed DC) using PH/EN mode to signal EN.

Without the motor, the motor is enabled, commutated, and the voltage across OUT1 OUT2 is the same as the truth table. When the motor is connected, Sometimes the motor works properly (during normal operation, the current starts at about 3.5A and runs at 2A), and sometimes nfault pulls down directly and does not work properly. When enabled, the chip immediately enters protection when the motor is commutating during operation. 

1) What could be the possible cause of the above issue?

2) How to set the ITRIP hardware version (non-SPI version)? 

3) Is it related to open load detection? How does this feature turn off? 

Thanks.

Best Regards,

Cherry

  • 0
    TI__Genius 15226 points

    Hey Cherry,

    Thank you for your question.

    1) It is hard to tell what the cause for the fault response is without taking some measurments. Have you looked at table 13 Fault Response in the datasheet to identify what is causing the issue? Such as is it a latched fault? is there an under voltage or an OCP event?

    2) In the hardware version of the device, the current trip limit is set to 6.5 A

    3) It might be related, we can test this by disabling the OL detection.For the hardware version of the device, the OLP test is performed at power-up or after exiting sleep mode if the nOL pin is left as a no connect pin (or tied to GND). If the nOL pin is tied to the DVDD pin (or an external 5-V rail), the OLP test is not performed by the device.

    Best,

    Akshay