UCD3138FW-PSFB: The output voltage of PSFB based on UCD3138 is too high when there is no load

Hello

I imitated the PSFB development board of UCD3138 and made a power supply

During the test, it was found that the output voltage was the target value when the prototype had a load of 30mA or more.

When the prototype has a load of 30mA or less, the output voltage will drift up by 1V.

I guess this may be due to the limitation of the minimum duty cycle when there is no load. I don't know if this is the reason.

I tried to reduce the blank time from 100ns to 25ns, and the output voltage no longer drifts up when there is no load,

but when the blank time is 25ns, the SR will burn when the power dynamic changes.

I don't know if there are other ways to solve the problem of no-load output voltage drift.

Thank you.