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.