DRV8350R: DRV8350R PWM output and GND layout path

Kevin Huang8

Part Number: DRV8350R

Two questions:
1. Buck output problem
DRV8350RS has a 12V to 3.3V step-down,
The PWM waveform of the SW output point sometimes appears as shown in the figure below, which is not a stable PWM output waveform.
What are the reasons for this situation? And is there any way to solve it?
Purple: FB point feedback voltage
Blue: SW point output PWM voltage after inductance
Yellow: SW point output PWM

2. About GND point configuration
In the datasheet, we did not find any suggestions on the GND point configuration.
Should the GND point be close to the high voltage or the GND terminal of the signal?
What is the impact of the difference between the two placements on the DRV8350R?
And what is the recommended configuration location?

over 2 years ago

0 Isaac Lara over 2 years ago

TI__Mastermind 19640 points

Hello Kevin,

Thank you for your questions.

1. Typically we see these voltage spikes due to a large current flowing back to the power supply causing these voltage spikes at different output terminals of your motor system. This happens because the motor can return stored energy and have the energy flow back to the supply and perhaps there is not enough bulk capacitance to absorb all this excess energy. You can go to this FAQ here that links different app notes or reasons why you are seeing voltage spikes in your system.

2.On the ground point configuration I recommend reading our app note on Best Practice for Board Layout of Motor Drivers, I will link it so that you may read it. There are various things to take into consideration such as board size, layers, heat, etc. This document goes over a good amount of things to consider for your system but if you have any questions feel free to reply here.

I hope these documents help!

Best,

Isaac

0 Matt Hein over 2 years ago in reply to Isaac Lara

TI__Mastermind 21805 points

Hello Kevin,

Do you have any further questions on this thread?

Thanks,

Matt

0 Kevin Huang8 over 2 years ago in reply to Matt Hein

Expert 2965 points

Thanks for your great support

0 Isaac Lara over 2 years ago in reply to Kevin Huang8

TI__Mastermind 19640 points

No worries Kevin, always glad to help out!

I will be closing this thread, feel free to click on ask a related question or ask a new questions.

Best,

Isaac

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DRV8350R: DRV8350R PWM output and GND layout path