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DRV8301: Strange behavoir

Simone Freato
Prodigy 170 points
Part Number: DRV8301

Hello.

I'm having exactly the same problem well explained in the thread "DRV8301 : Trickle Charge Circuitry and Internal Handshake".

I'm driving two DC motors with a terminal fixed to VCC and the other driven in PWM. When i drive the motor 1 the low side driver of motor 2 goes in a state where it ignores the logic input. 

Even more strange is that after about 1 second of 50kHz pulses the low side driver starts to work again.

  • 0
    TI__Guru** 114905 points
    Hi Simone,

    Have you read section 8.1.1 of the revision F datasheet:

    The DRV8301 gate drivers may not correctly power up if a voltage greater than 8.5 V is present on any SH_X pin
    when EN_GATE is brought logic high (device enabled) after PVDD1 power is applied (PVDD1 > PVDD_UV).
    This sequence should be avoided by ensuring the voltage levels on the SH_X pins are less than 8.5 V when the
    DRV8301 is enabled through EN_GATE.

    Do you have this condition?
  • 0 in reply to Rick Duncan
    Prodigy 170 points

    Hi Rick,

    thanks a lot for your reply.

    I'm sorry but I missed that paragraph, completely. And yes, that's exactly the condition I have, since one of the poles of the motors is permanently connected to the positive terminal of a battery. Worst of all, I can't do anything else, since I have to preserve backward compatibility with an old board which drives the motors in that way.

    In the meanwhile I have seen that pulling the BST_x pins to GND with a 100k resistor apparently fixes the problem. Obviously this is not ad acceptable solution for a production board, but it tells to me that there could be a clean method to come out from this situation.

    Do you have any suggestion?