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BOOSTXL-DRV8305EVM: No PWM signal without load, motor driver only works under load BOOSTXL-DRV8305EVM

Part Number: BOOSTXL-DRV8305EVM
Other Parts Discussed in Thread: DRV8305,

Hello,

I use the TI BoostXL DRV8305EVM to control a DC motor. Can you tell me why the motor driver only works under load? If I measure the output voltage, I have to use a load resistor in parallel to get the correct output signal (its not just a pull down resistor with 10KOhm, it has to be an (small) performance-resistant.

Can you tell me the reason and a possibility to solve the problem?

Thank you very much

Best regards

Tobi

  • Hi Tobi,

    Have you examined the inputs to confirm INH_x and INL_x are toggling?
    Do the outputs following the inputs with no load?
    Do the inputs stop after some time?

    The DRV8305 acts on the inputs provided. If the firmware detects the motor is not spinning properly, it may stop and wait some time before trying again.
  • Hi,

    Thanks for the answer.

    The inputs INH_x and INL_x are working (PWM signal), but the Output are not following the inputs without load.

    The Inputs Aalso do not stop after some time.
    I have already tried the second 8305 BOOSTXL but there is the same problem.

    Do you have a solution for this problem?

    Thank you very much

    Best regards

    Tobi

  • Hi Tobi,

    You have two BOOSTXL-DRV8305EVM , correct.

    Assuming you have two launchpads, you can compare the loaded versus unloaded EVMs to determine the reason the outputs are not following the inputs.

    The DRV8305 should operate when loaded or unloaded assuming the device is awake (WAKE is high), the outputs are enabled (EN_GATE is high), and has no faults (nFAULT is high).
  • Hi Tobi,

    I have not heard from you for some time, and am assuming your issue was resolved.

    If it was not please reply to the post, or open a new one if this one is locked.