UCC28180EVM-573: What is the purpose of diode D2 across the inductor and output diode D3?

Bobby Lam95

Part Number: UCC28180EVM-573
Other Parts Discussed in Thread: UCC28180

Hi, I am looking at the schematic of this UCC28180EVM-573. Noticed there is a diode D2 across the inductor and output diode D3. what is the purpose of this D2 diode? the datasheet does not have it in the circuit. Thanks

over 4 years ago

0 David Huang33 over 4 years ago

TI__Genius 9140 points

Hi Boby,

thanks for using UCC28180. D2 is designed to be a diode for lighting or surge.

It is needed when the power supply needs to pass lighting or surge test.

0 Bobby Lam95 over 4 years ago in reply to David Huang33

Intellectual 320 points

Humm...Interesting, can you explain how it electrically prevents the surge or lightening? Thanks

Bobby.

0 David Huang33 over 4 years ago in reply to Bobby Lam95

TI__Genius 9140 points

Hi Bobby:

when the lighting or surge happen, the impedence of D2 is lower than inductor add D3, so the energy from lighting or surge will transfer directly to the PFC bus cap without going through the PFC inductor and D2. And this will help to protect PFC mosfet from demaged by the energy from lighting or surge.

I hope my answer is clear here.

0 Bobby Lam95 over 4 years ago in reply to David Huang33

Intellectual 320 points

Thanks for the explanation David.

Bobby.

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UCC28180EVM-573: What is the purpose of diode D2 across the inductor and output diode D3?