BOOSTXL-DRV8323RS: The difference between the sampled and actual current values is large

Hi Joshua,

Thank you for the support.

The configuration of 4 mΩ plus a gain of 10 and configuration of 7 mΩ plus a gain of 5 are all set and calculated by following the recommendations in datasheet.

Thanks and regards,

Cherry

Hi Cherry,  

Thank you for the information.  Would you be able to provide the values and waveforms of the CSA outputs where this current difference is noticed?  

If you could also provide the schematic(s),  that would be helpful as well.  

Best Regards, 

-Joshua 

Hi Joshua,

Joshua Maize said:

Would you be able to provide the values and waveforms of the CSA outputs

Could you help share which pins are you referring to when saying "CSA outputs"?

And please see a part of the schematic:

Thanks and regards,

Cherry

Hi Joshua,

Giving more details as below:

The following figure is the measured values:

A-actual current

B-sampling current

C-sampling current/actual current

D-Theoretical op amp output voltage 

E-The actual ADC read voltage 

F-The actual op amp output voltage 

G-The actual voltage corresponds to the ADC value 

H-The theoretical voltage corresponds to the ADC value 

I-actual ADC value

And the code configurations are as follows:

Thanks and regards,

Cherry

Hi Cherry,  

Thank you for the information and let me determine this week if there is anything else needed after review.  

Best Regards, 

-Joshua

Hi Joshua,

Thanks and please see CSA output waveform(yellow) as follows:

Thanks and regards,

Cherry

Hi Cherry, 

Thank you for the waveforms.  Is there any (RC) filtering implemented on these CSA inputs/outputs? And could you try measuring the CSA outputs again after performing "Auto Offset Calibration" as detailed in section 8.3.4.3 of the DRV832x datasheet?

Best Regards,

-Joshua

Hi Joshua,

Joshua Maize said:

Is there any (RC) filtering implemented on these CSA inputs/outputs?

They've tried RC filtering but the improvements are not obvious.

Joshua Maize said:

And could you try measuring the CSA outputs again after performing "Auto Offset Calibration" as detailed in section 8.3.4.3 of the DRV832x datasheet?

Measuring the output but the issue persists after performing Auto Offset Calibration(both software and hardware).

Thanks and regards,

Cherry

Hi Cherry, 

Thanks for the clarification. 

I'll keep you updated as I continue to look into the info you've provided. 

Best Regards, 

-Joshua

Hi Joshua,

Thanks and expect the response.

Thanks and regards,

Cherry

Hi Cherry, 

Our team is currently out of office due to US holidays, and will be returning next week.
Please anticipate a delayed response to your question - and feel free to share additional details which may be helpful to the analysis in the meantime.

Best Regards,
Andrew

Hi,

Just a reminder, this issue is still ongoing and the customer is wondering is there any updates?

Thanks and Regards,

Cherry

Hi Joshua,

We have sawpped to the recommended component(1uF->0.1uF),the problem still exists.

We also modify the software configuration by switching VREF_DIV bit(0b, 1b)，there hasn't been any change.

Are the two troubleshooting items you requested the idea of calibrating the reference voltage？

Hi Yi,

Joshua is out of office over the holidays but will be returning the first week of January. He will work to provide a response when he is back in office. Thanks for your patience!

Regards,

Anthony Lodi

Hi Yi,  

I am back in office and apologize for the large delays. 

Yes, the previous two items were to potentially calibrate the reference voltage that could offset the csa measurements,  and I would like to ask the exact method used to measure the actual phase current compared to the csa output that is appearing larger?  I would like to ensure this measurement is being taken in the most optimal place to reduce any error.  

Best Regards, 

-Joshua