Flyback switching power supply flickering debugging and proper software for its simulation

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we are using PIExpert V6 for building one fly-back switching power supply, SO the calculated power supply is this kind:

and the Altium files is here:

source files are here:

source files

or :

Another link for source files

So the problem is here,When we connect the 220V AC voltage source to our power supply and connect the LED lamp to output,the LED lamp becomes on for only one second and then is off (pulsing), then on then off and so on ... . So what do you think about this kind of operation causes and the way for fixing it.

And finally is there any professional software exist for simulating this kind of power supply before building it physically, we could not simulate this circuit in Altium V9 because there is no TNY280PN and the proposed transformer , so if you have simulated this kind of circuit please guide us to the correct way.(Any idea about simulating with MATLAB, PSPICE or ... and examples ).

Thanks a lot for your attention .


I think, we have same problem, but I have it with LNK410, this is posted, I found that the blocking diode in the clamp circuit is making this, I take this off and is working, but is not correct, you probably can change the blocking diode with other biger.

I been waiting for some support of PI eng. 


I think your problem refers to maximum current limit of TNY280. Becuase you dont have current control circuit and maybe your output votage is high enough. So whenever you connect LED to output it acts like overload condition and you see TNY280 self turn off because of maximum current limit.

there are two solution for you:

simple: set output voltage same as LED nominal voltage.

better: try extra currnt control circuit.


I agree with Allahyar. Your circuit does not have a CC control which causes TNY280 to auto-restart due to overload condition.

If you want to work in CV mode, put a resistor in series with the LED. The LED should be below the CV setpoint of the driver. The resistor can be calculated as (Vout-VLED)/IOUT.

This approach, however, will dissipate power on the resistor so it's probably better to use CC control.

You may check LYT-4 which works in CC mode.