LNK364PN Power supply stop work

Hi yanghooyak,

Thank you for your interest in using Power Integrations' part.

Regarding your inquiry, can you provide me your schematic and probably you can attached your PI Expert design so I can have more information of your design.  Thanks.

Hi , PI-Mallora
Thanks for your reply . Please check the attachment for details.

Hi yanghooyak,

Thanks for the information.  Looking at your schematic, it seems that you have forward operation instead of flyback.  Can you give me a waveform with VDS voltage and D12 current or voltage at the same time.  When you get D12 voltage instead of current, please have the positive probe at the cathode then negative probe at the anode so we have common reference. When you get D12 current instead of voltage, just follow current direction from anode to cathode.  Thanks.

forward operation instead of flyback? Why? What's the difference between my design and the reference design(LNK364_V120_Sim.uds)? 

Please refer to the attachment (EE13-Simple-Test.png)

Thanks for your reply . Please check the attachment for details.

Hi yanghooyak,

Basically it is the transformer orientation that dictates the flyback operation.  Your secondary winding should be out of phase with the primary winding.  So when your flyback MOSFET is ON, your secondary diodes D12 and D13 should be reverse bias or not conductiong.  Then when your flyback MOSFET turns OFF, that is the time that the D12 and d13 should conduct in a forward bias.  If your MOSFET is ON and your D12 and D13 is also conducting, then your have wrong transformer orientation.  You have to interchange termination of your primary winding.  Thanks.