der318 less efficiency at 230V

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   we followed  der318 for making a 23W tubelight driver and it works. But draws more input power from 230V-243V range. From 180V to 228V and above 245V,  we get 80% efficiency. And between 230V-243V we get only 72% efficiency. Kindly explain why the ckt  draw more input current in this particular input voltage range. Pls note output power remain steady through 180 - 265V. We use same components as in the der318.




Did you change anything from the original DER-318? I ask this because I wonder why youre getting very low efficiency compared with the reported efficiency in DER318.

One possible reasson in efficiency drop at high line is if you trigger the OVP circuit formed by VR11. You can disconnect VR11 and confirm whether the efficiency drop is from this circuit.