Ferrite core transformer
I used PI Expert 7 and designed a 22v - 1.5A power supply using TNY280. The circuit seems to work fine but both transformer and IC shoots up very high even after reducing the load to less than 1.2Amps. When I checked again the primary & leakage inductance of the transformer is very high even though I used exact number of turns as per PI expert. May be the AL values may be different. Could this be the reason? Then is there any way to decide Np & Ns based on AL values? -Krishna
Comments
Yes I checked transformer design. And even changed to larger core. Now I.C is getting heated up. What else could be the cause?
Hi,
I order to help you further, please provide a copy of the schematic, transformer design and construction and a copy of the board layout.
I would prefer a .jpg or a .tif or a .pdf file.
Please check:
1. If you have used the clamp circuit as recommended by us in our application notes/datasheet or as recommended by PI-Expert.
2. Please verify if you have provided sufficienct area on the circuit board which works as a heatsink for the TNY-280. Please review the recommended board layout in our data sheet and the notes/recommendations.
3. If you still have not found the problem, please send us the drain-source voltage waveform and the drain current waveform and also let us know of the transformer primary inducatance and leakage reactance.
Regards
PI-Sarek
Based on the information provided, I wonder if your transformer connections are reversed that is instead of a flyback, it has got connected as a forward?
Please verify.
Regards
PI-Sarek