Curious about the toroid - it's probably just to smooth out the waveform. I've seen them in electronic halogen light "transformers", as well. But I'm thinking of how I can use that chip in a temperature (or resistance) sensing glow driver. It should replace a bunch of components on the old [link=http://geology.um.edu.my/ntaibpublic/Misc/ETI%20glow%20driver/ETI-1516%20Article.pdf]ETI-1516[/link].

Iskandar