DRV8834: DRV8834 waveform problem

Terry Wu2

Expert 2110 points

Part Number: DRV8834

Hello Sirs,

Would you pls advice about this waveform drop issue ?

INDEX & 1/8 micro stepping

Stepping motor is 32 steps/turn , 3.3V +/-10% .

Attach file is waveform capture and schematic.

Many thanks !

DRV8834 waveform problem.pptx

over 7 years ago

0 Rick Duncan over 7 years ago

TI__Guru** 114905 points

Hi Terry,

It appears as though the points are the 0 current points in the indexer. Can you confirm this?

If this is true, this is not a waveform drop. The outputs are disabled, causing the voltages to change to VCC+0.7V and GND - 0.7V while the current in the winding drops to zero. Once the current reaches zero, the remaining voltage is the BEMF of the motor.

0 Terry Wu2 over 7 years ago in reply to Rick Duncan

Expert 2110 points

Hello Duncan,

Attach file CH4 is winding current waveform. Looks like it is zero .

We try full step and no this problem but 1/2 micro step , 1/8 and 1/32 step have this drop waveform .

Would you pls help to comment ? TKS ~

0 Rick Duncan over 7 years ago in reply to Terry Wu2

TI__Guru** 114905 points

Hi Terry,

Thank you for the confirmation.

Any microstep mode will have this behavior at the 0 current step. Full step does not have this behavior because the winding is always driven (there is no zero current step).

0 Terry Wu2 over 7 years ago in reply to Rick Duncan

Expert 2110 points

Hello Duncan,
I got it and many thanks your fully support ! TKS ~

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DRV8834: DRV8834 waveform problem