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DRV8305-Q1: avdd, capacitor , fault

Part Number: DRV8305-Q1

Hi~ All

Designed DRV8305-Q1 and AVDD failure happen..

 

Datasheet recommend 1uF output cap for AVDD, but customer used 4.7uF from previous design(DRV3245-Q1 circuit.)

 

Please, refer failure symptom and let me have feedback for below questions.

 

  1. AVDD cap, 1uF value is critical value? Must keep 1uF? Should not use like 4.7uF?
  2. Must keep 1uF, failure mechanism when use 4.7uF AVDD cap. Why failure happen?
  3. In DRV3245-Q1 design, SL used AVDD cap as 4.7uF as guide, any difference between 3245 and 8305 AVDD LDO?
  4. Any recommendation for power sequence? Not to hit failure mode?

Thanks.

  • Hi Jin-Suk,

    AVDD cap, 1uF value is critical value? Must keep 1uF? Should not use like 4.7uF?

    We recommend using a 1uF capacitor as specified in the datasheet as the device was validated and designed with this capacitor value.

    Must keep 1uF, failure mechanism when use 4.7uF AVDD cap. Why failure happen?

    1. Does the AVDD fault error persist after asserting the CLR_FLT bit in register 0x06?

    2. Could you provide a capture of AVDD and PVDD at startup and the schematic?

    In DRV3245-Q1 design, SL used AVDD cap as 4.7uF as guide, any difference between 3245 and 8305 AVDD LDO?

    The main differences are the deglitch time and max current draw from AVDD.

    The 8305 has a 1.5 - 2 us deglitch time while the 3245 has a 8-10 us deglitch time.

    The 8305 can support up to 50 mA of current draw while the 8245 can support up to 100 mA of current draw.

    Any recommendation for power sequence? Not to hit failure mode?

    I would recommend trying to assert the CLR_FLT bit in register 0x06 after startup to see if the fault error goes away after startup.

    Best Regards,

    Joshua