Ac to DC without transformer

Do a web search on off line power, or off line switcher. Lots of info.

At these power levels (1/2 Watt), switchers aren't much smaller than linear transformers. If ALL of your circuitry is isolated properly, you can consider using series capacitance instead of a transformer, but you'll need about 3uF, and properly rated capacitor(s) could also be about as large as a 1VA transformer. You might want to put your energies into looking for the smallest possible linear transformer, especially if your product has any exposed metal. Paul Mathews

No single chips that I know of, but check out Power Integrations and their LNK304 series of chips

At .1A you need too big a series cap to do a simple ac coupled bridge converter for it to be cheap, however, if you can lower current to about 20ma it is a good way to go.

Of course I'm thinking you don't need isolation?

Rocky