DRV8833: A query regarding the waveform for output

Katherine Wang

Part Number: DRV8833

Hi Team,

The electric motor driver has no load. The input at AIN1 is 0V, and that at AIN2 stands at 20KHZ. The duty cycle is 40%, and the square wave has an amplitude of 3.3v as shown below.

The yellow line in the figure stands for the AOUT2 waveform, and the blue one represents the AIN2 square wave. Why does the yellow line for output have a capacitive effect and fall slowly?

Kind regards,

Katherine

over 2 years ago

0 Akshay Rajeev Menon over 2 years ago

TI__Mastermind 23306 points

Hey Katherine,

Thank you for your question.

The AOUT2 is falling slowly due to the presence of some sort of parasitic capacitance on the output of the driver. You might observe this you happen to have any capacitors placed on the output of the driver.

Best,

Akshay

0 Katherine Wang over 2 years ago in reply to Akshay Rajeev Menon

TI__Intellectual 2210 points

Hi Akshay,

But I did not place any capacitors. Could it be because of the copper?

Regards,

Katherine

0 Akshay Rajeev Menon over 2 years ago in reply to Katherine Wang

TI__Mastermind 23306 points

Hey Katherine,

It could be effect of parasitic capacitance.

Another reason could be that you are using the motor in coast mode. So an experiment to see if this behavior changes depending on which decay mode is being used, is to use the motor in forward/brake mode.

So you would have AIN1 set to logic high, and AIN2 PWM, with 60% duty cycle. And test to see if the voltage drop happens quicker.

Best,

Akshay

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DRV8833: A query regarding the waveform for output