Primary clamp for 295W pushpull SMPS?

[zenerbjt]

I wish to do a 295W Non-isolated push-pull converter. Vin is 100V, vout is 24V. Fsw = 150kHz.
We wish to use the LTC3723-1 pushpull controller. And this used with the LTC3901 synchronous rectifier driver.
(attached is LTspice sim and PDF schem)

Do you agree that the only way we can deal with primary leakage is to quench it with TVS’s of voltage >Vin?

LTC3273-1 datasheet
https://www.analog.com/en/products/ltc3723.html


LTC3901 datasheet
https://www.analog.com/media/en/technical-documentation/data-sheets/3901f.pdf

 

[KlausST]

Hi,

Do you agree that the only way we can deal with primary leakage is to quench it with TVS’s of voltage >Vin?

I'd say:
"...with TVS’s of voltage >2 x Vin?"

Klaus

 

[Easy peasy]

how much is the pri side leakage? every effort should be made to reduce it esp for low volts ( 100V ) and non - isolated ...

Else R-C snubbers are your friend - on the o/p too ....

--- Updated Aug 12, 2020 ---

any TVS should be 220 - 250V as its a push-pull ...

 

[zenerbjt]

Thanks, would you agree that when a primary fet conducts through its coil half...then the other coil half has vin impressed on it?

 

[Easy peasy]

it's a transformer - if you have 2 wdgs the same and you put 100V on one - you get 100V on the other too ...