Tool/software: WEBENCH® Design Tools
We have developed the AC-DC Adapter circuit using UCC28630DR for 160V to 260V input AC supply working upto 100 watts. We faced the following problem during testing of the circuit.
The AC input voltage was set to 170V AC and unit was turned ON, we were able to get DC voltage.Capacitor C2 output around 280V DC, this is fed to primary points of transformer. The supply point VDD of IC was13V initially when we switch on the circuit and voltage varies in between 13V to 8V later. But no voltage was observed across secondary and auxiliary points of transformer. At this stage R8 resistor valve was 6.49 Kilo ohms (Rbld). We decreased R8 resistor valve to 3.75 Kilo ohms (Rbld) but still no voltage was observed across secondary and auxiliary points of transformer. VDD of IC was13V initially when we switch on the circuit voltage varies in between 13V to 8V. We request you to advice us to solve the issue.