LinkSwitch-HP family: Unable to use LNK6776E to Generate a 120 V output voltage

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I want to generate a 120V DC output voltage based on the reference design in LinkSwitch-HP datasheet. The related schematic is attached. Now, when there is 110 V ac 50 Hz input, the output voltage rise to around 50 V then it will slowly go down to zero. Then will rise again. The related figure is also attached. However, when there is 220 V ac 50 Hz input, the output voltage will maintain zero.

Can anybody explain what happened to my circuit? Thank you for your help.

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schematic.png36.12 KB
Output_voltage.jpg157.43 KB

Hi yhuang_111,

Looking at the schematic you provided, you used 470nF as Cbp. At low line (110VAC) it seems that the output response is auto restart, which if we base on the Cbp used will be caused by lost regulation. At high line, we can assume that the output response is latching which may be caused by OVP.

I will need more information to be able to help. May I request for the transformer construction you used? Also, after trying to power the unit, were there any components that were damaged?