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DRV8825: DRV8825 motor driver chip has noise problems when the motor runs under load

Annie Liu
Genius 10295 points
Part Number: DRV8825
Other Parts Discussed in Thread: DRV8711

Hi Team,

The customer is experiencing below issue and needs your help.

DRV8825 motor driver chip has noise problems when the motor runs under load. This does not happen when the customer changes other chips. He used two current probes to look at the two phase current waveforms respectively, suspecting that the phase current glitches are large. Customer would like to know why this happens?

The yellow one is the current of one phase of drv8825, and the schematic diagram

  • 0
    TI__Guru 56650 points

    Annie,

    "DRV8825 motor driver chip has noise problems when the motor runs under load. This does not happen when the customer changes other chips. He used two current probes to look at the two phase current waveforms respectively, suspecting that the phase current glitches are large. Customer would like to know why this happens?"

    Do you mean this does not happen when the customer changes other DRV8825?

    If the customer has both good one and bad one, what does good waveform look like?

  • 0 in reply to Wang5577
    TI__Genius 10295 points

    Hi Wang Li,

    Customer replaced other stepper motor drive modules CL3-E. The green in the picture above is the CL3-E waveform. The yellow is the phase current waveform of 8825. There is differences between them, the CL3-E PWM chopping frequency is about 60, and 8825 is about 30.

    Annie

  • 0 in reply to Annie Liu
    TI__Guru 56650 points

    Annie,

    This post talks about DRV8825. But, the schematic is DRV8711.

    The waveform shows DRV8825 output current has a higher ripple than CL3-E driver's. If the customer uses the DRV8825, please change the decay mode pin setting to get the lowest noise.

  • 0 in reply to Wang5577
    TI__Genius 10295 points

    Hi Wang Li,

    Sorry. This time, the customer provided the correct circuit diagram.

    He tried three modes, the noise is almost the same. At present, the current waveform in the mixed mode is the best, and the current ripple is still large. And the PWM chopping frequency is around CL3-E 60, and 8825 is around 30. What effect does this have on the noise of the motor during operation？Are there any other reasons that may cause the operating noise to increase？

    Thanks

    Annie

  • 0 in reply to Annie Liu
    TI__Guru 56650 points

    Annie,

    People can hear from 20Hz to 20kHz mechanical vibration. The winding current is proportional to the motor torque. When there a 20Hz to 20kHz torque vibration in the motor, people could hear it.

    CL3-E PWM chopping frequency is around  60kHz, and 8825 is around 30kHz. They both are higher than 20kHz. When the stepper motor runs, the step rate could be lower than 20kHz. We can hear the motor running sound which could be much louder than the motor driver's PWM noise. So, does the waveform show the winding current when they check the noise? Does the noise come from the motor? If the noise comes from the motor; three decay modes cannot help reduce the noise, I don't have other method to reduce the noise unless changing the motor or changing the input power supply voltage.