timer - Delayed power supply startup

I would like to make a circuit that turns on a power supply to a microcontroller after holding down a button for a period of time (say 2 seconds). To make matters slightly more complicated, if possible, I would like to use this button as an input also. The power off could come from another switch if need be.

I was thinking of something like a latching RC circuit to an zener that switches a MOSFET on to allow power through. Ideally the solution would not consume power until the switch is pressed.

Thanks for any help

Answer

You may want to search for "power supply sequencers" and "powerpath controllers" at Linear Technology, Maxim and TI. Those devices integrate a variety of sequencing and control functions including on/off, delay start, sequencing of multiple supplies. Some have integrated FETs.