UCC28064A: Snubber circuit requirement

Akash S

Part Number: UCC28064A
Other Parts Discussed in Thread: TIDA-010015

Hi,

Our design is based on TI reference TIDA-010015.

In the PFC Boost section, the mosfet Q12 is getting damaged when supply is switched off at heavy loads (say 20A) at DC inputs. This is due to the overshoot due to ringing at the switching node as shown in the image. The mosfet is rated at 650V whereas the shoot goes up to 730V.

Please suggest a suitable snubber circuitry for the above application and the corresponding calculation and tuning process.

over 5 years ago

0 Benjamin Lough over 5 years ago

TI__Mastermind 26645 points

Hi Akash,

These steps should let you calculate a snubber that will critically damp the ringing:https://e2e.ti.com/blogs_/b/powerhouse/archive/2016/05/05/calculate-an-r-c-snubber-in-seven-steps

This would be placing a resistor in series with a capacitor across the rain to source of each MOSFET.

Best Regards,

Ben Lough

0 Benjamin Lough over 5 years ago in reply to Benjamin Lough

TI__Mastermind 26645 points

Hi Akash,

Could you check when the gate of Q10 is turning off? It may be contributing to the spike by making the equivalent impedance of the output cap + RF1 high impedance leaving the inductor current no where to go but peak charge the Coss of Q12. If this is happening, we can add a circuit to keep RF1 shorted while the PFC output is still high voltage.

Best Regards,

Ben Lough

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UCC28064A: Snubber circuit requirement