DRV8803 About OUTPUT issue

masahiko shimizu

Other Parts Discussed in Thread: DRV8803

My customer is using DRV8803.
He has the following issue.

OUT1 and OUT2 turn on at the timing of excitation switching to OFF state even though the DRV8803 inputs don't change.
Please see the attached file. This is waveform and detail of issue.
Could you advice me?

Thanks
Shimizu

DRV8803 output waveform.xlsx

over 9 years ago

0 Wilson Zuo over 9 years ago

TI__Mastermind 26065 points

Hi Shimizu

Is it possible to plot IN3 or IN4 as well in the same waveform with the issued IN1(or IN2) and OUT1 (or OUT2)? I just want to confirm the "turn on" issue happened align with the IN3 or IN4 OFF.

It is possible that the self inductance of one coil of the unipolar motor causing this waveform when half of the coil is switched OFF. So I mean the turn on term is not truly turned on, but looks like it was turned on. I will try to figure out ways to identify this tomorrow.

Is this affecting the normal running of the motor?

Best regards,

0 masahiko shimizu over 9 years ago in reply to Wilson Zuo

Guru 11235 points

Hi Wilson

Thank you for your support.

I attach waveform of IN1/OUT1 and IN3/OUT3.

Could you confirm this waveform and let me know your idea?

I think that this behavior is happened align with the IN3 and IN4 OFF from this waveform.

But I don't know reason. Please advice me?

Thanks

Shimizu

DRV8803 output waveform2.xlsx

0 Wilson Zuo over 9 years ago in reply to masahiko shimizu

TI__Mastermind 26065 points

Hi Shimizu,

Please refer to my drawing below on the explaination. So in one word, it is due to the self inductance and it is a normal thing on unipolar motor.

Best regard,

0 Wilson Zuo over 9 years ago in reply to Wilson Zuo

TI__Mastermind 26065 points

I'm not able to identify whether the output goes to -0.7v in your current scaling of the test results. Please help to verify our theory with a close look at the voltage level during the "issue" time.

Best regards,

0 masahiko shimizu over 9 years ago in reply to Wilson Zuo

Guru 11235 points

Hi Wilson

Thank you for your support.

I confirm whether the output1 goes to -0.7V.

Please wait.

and could you advice me? Is there the method of preventing this behavior?

Thanks

Shimizu

0 Wilson Zuo over 9 years ago in reply to masahiko shimizu

TI__Mastermind 26065 points

HI Shimizu

Is there any system problem causing by this issue?

This voltage waveform has no risk to the driver or the motor. It can be treated as a special recirculation manner of the unipolar stepper motor.

Best regards,

0 masahiko shimizu over 9 years ago in reply to Wilson Zuo

Guru 11235 points

Hi Wilson

Thank you for your support.

I confirmed more detail waveform of VOUT1-pin.

I have attached this file.

VOUT1 is -0.8V(like -0.7V). your answer is correct.

There is no problem causing by this issue.

I will explain this behavior with this information to my customer.

Your support is very helpful for me. Thank you a lot.

Thanks

Shimizu

DRV8803 output waveform3.xlsx

0 Wilson Zuo over 9 years ago in reply to masahiko shimizu

TI__Mastermind 26065 points

Hi Shimizu

Thanks of your confirmation. We can leave this as a completed story here now for similar questions in future.

Best regards,

Motor drivers

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DRV8803 About OUTPUT issue