TNY278NP low output voltage (12V -> 11.5V)
I have built a Flyback converter with a TNY278PN and the PI Expert Suite
with a little modifications.
- The primary inductance of the transformer (hand-made) is 835uH.
- Add a 150ohms resistor in the coupler (AN-14 recommendation).
- C5 replaced by two 2.2nF in series.
- R3,R4 deleted.
- R1 replaced by two 100Kohm in series.
- Coupler LTV817A -> PC821.
- Diode replaced by similar.
When I turn on power (AC100V 50Hz) the output not rise to the 12V and keep stable at 11.5V with not load.
Where is the problem?.
I attach the design sheets of the PI expert and one more with the modifications (8 pages in total)
PD. Excuse me for my ugly english