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DRV8846: Motor jitter

Part Number: DRV8846

Hi Team,

The customer made a batch of motor drives with DRV8846. The hardware circuit is built in strict accordance with the typical circuit given in the manual. 

The machine has a boot process and a command motor rotation process.

The software configuration is 32 subdivisions, 75% current, attenuation mode is manual, and Toff is high resistance. Switch the machine on and off repeatedly and command the motor to rotate. 

  • The motor may be very quiet, or it may be very noisy, and the motor is shaking, and the probability of noise is very high; 
  • If the sound is very light after power on, as long as the power is not turned off, the sound is always very light;
  • If the motor is noisy after starting up, the noise will always be loud as long as it is not turned off

Motor noise file: 20210520_153847.m4a

When the motor makes abnormal noise, the waveform at AOUT1 is:

Software modification:

  • After the machine is turned on, the attenuation mode is automatic, Toff is high resistance
  • Before commanding the motor to run, change the attenuation mode to manual, repeat the test in a short time, the sound is very light, no noise

If he does not modify the software and uses a hot air gun to re-weld the DRV8846, and repeated tests within a short period of time, there is no loud motor noise.

Is this phenomenon related to the configuration of the software or the welding of the chip?

Thanks,

Annie

  • Annie,

    Can you send a schematic please so I can check configuration of pins?  I am not sure what "attenuation mode" is...can you clarify with pin settings?  

    Are there any faults during this operation...nFAULT = 0?  

    Can you send current waveforms?  For a stepper motor, this is the best way to debug.

    Regards,

    Ryan