DRV8353R: Confirmation of RC snubber measurements

Martin123

Prodigy 175 points

Part Number: DRV8353R
Other Parts Discussed in Thread: DRV8353

Hello,

we have followed “[FAQ] Proper RC Snubber Design for Motor Drivers”

Our system is a DRV8353 with a 48V lithium battery.

Attached oscilloscope probe at VCC at drain on phase and GND at motor output(source).

Here is the first scope images without any snubbers

We then used a 100pF 100V capacitor and a 0R resistor and this is the image we got.

Next image is same measurements on lower mosfet, with 100pF capacitor from previous scope image

High side motor at 2A,

First three scope images is done at same motor load.

Can't see in the guide what ringing values are acceptable, so asking here if this look ok.

Martin

over 3 years ago

0 Aaron Barrera over 3 years ago

TI__Mastermind 26046 points

Hi Martin,

RC snubbers reduce ringing at the MOSFET sources (SHx, SPx) so EMI performance is better. EMI can lead to electrical overstress over time on the DRV device or MOSFETs, depending on the amplitude and frequency of the ringing.

If you have EMI/EMC requirements or standards for your application, you should mitigate the ringing by adding enough capacitance to the RC snubber to dampen the oscillations. Your RC snubber is mitigating the original ringing well. You can also use lower IDRIVE currents to reduce ringing.

Visit this resource to determine how to lower ringing: https://www.allaboutcircuits.com/industry-articles/understanding-and-mitigating-motor-driver-board-parasitics-through-simulation/

Thanks,
Aaron

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DRV8353R: Confirmation of RC snubber measurements