Simplest Way to step down the 220AC with more than 10% efficiency
What you are looking for is called an off-line power supply.  A quick search reveals the Fairchild Semi FSAR001.  Putting in 80 - 240 Vac yields 5Vdc at 35 mA max.

There are many more around.


it is NON-isolated!!! meaning this is not a design to put into devices that people will handle - Full Stop.


let me repeat that, this is a lethal circuit, but perfectly reasonable to use under the right conditions.

Here is a snip from page 2 of the datasheet.


This answer does not address your question concerning a chip design.  Which I can answer but I'm hoping that the real problem is solved with this lead and direction.