I am using PI Expert Online (this) to design a smps circuit for 5V, 2.5A output. I already have TOP258PN IC with me so built circuit for that.
Change from schematics: I am not using choke and using SR360 as output diode.
I am able to get 5V output when no load is connected. But as soon as I add load (5 ohm test load for 1 A current), I get current at right value but within few second voltage drops to zero and transformer makes noise. And then it again goes up and then down and it continues. Just before transformer goes to zero, it makes sound. I made transformer design as given by the PI Expert software (which says Design Passed).
Is it problem in transformer or some other thing like switching?
Leakage inductance is estimated to be 93 uH but is 124 uH in real. Will that be a problem?