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SMPS Pulsing in hiccup mode

fing
Associate II

Hello,

I have designed and assembled a SMPS based on the EVAL-STCH03-45W evaluation board. What I have noticed, is that the power supply is outputting 1 Hz pulses with short buzzing sounds. These symptoms usually mean the hiccup mode is activated. However, I couldn't really find the problem that could cause the STCH03 to go into hiccup mode. I also noticed that the secondary side mosfet (STL90N10F7) was dead short, which is interesting because the components are sourced from Mouser. After replacing with another (but not the same) MOSFET the problem was still present.

Can you guys check my schematic whether it is correct, or maybe give some tips on where I should look for the cause of this problem?

smps.png

 

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