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DRV8835: Questions about motor driver drv8835

Gil dong Hong
Prodigy 10 points
Part Number: DRV8835

[I used a translator.]

Hi,

 

I run the motor in "drv8835 Fast DK Mode".

​The following waveform appears on the oscilloscope.

When the pulse is low, about 6~7V is output

Is it working correctly?

Is it normal not to fall to 0V?

 

When operating in Slow DK (phase / in mode), the motor will run slowly even with a small duty ratio.

However, when operating with Fast DK, the motor does not operate at a small duty ratio, and the motor operates only when the duty ratio has risen above a certain value.

Is it working right?

Do you have a guide or a workaround?

 

Thank you in advance for your reply.

Have a nice day.

  • 0
    TI__Guru** 114905 points
    Hi Gil,

    Please confirm you have set the MODE pin to low.
    Also what is the PWM frequency?



    Fast and slow decay are working correctly.

    In Fast Decay (Coast), the outputs are disabled. When disabled the voltage should go to -0.7V or VM+0.7V for a short time. If the current is removed from the coils, the outputs then can float to any voltage.

    In slow decay (Brake), the outputs are not disabled. Any current injected in the winding during forward or reverse may remain until the next PWM cycle begins. If current is remaining, the next cycle can increase the current and eventually the motor may move at low duty cycles.

    If you have a current probe, you can see the currents during PWM. If not, you can try to measure the voltage across the output with a DMM.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Gil,

    We have not heard from you in some time, and are assuming you have resolved your issue.

    If you have not, please reply to the thread or if the thread is locked select "Ask a related question".