Diode after power switch

[VoidIfRemoved]

I'm working on a project involving a microcontroller where I need it to consume no power when off, and then when the button SW1 is pressed the power switches on and stays on until the microcontroller sends the OFF signal. So far I have this. VCC is the power that comes from the battery, and V+ is the power going to the rest of the circuit (after having typed that, I've realized it'd probably make more sense to have those two labels switched, but I digress)



Because the microcontroller is going to have a decoupling capacitor next to the power pin, I thought that I should put a diode after the toggle section so that the latching transistor will shut off properly and not be kept going by charge coming from the capacitor, and to generally isolate the toggle section from the rest of the circuit. Will this work as I'm thinking, and is the diode even necessary?

Also, any feedback on the design in general would be appreciated.

[Mr.B]

Q3 is going to clamp your VCC to GND... Not a good idea.

Read these two threads:
https://www.eevblog.com/forum/projects/mosfet-power-switch-with-auto-off/
https://www.eevblog.com/forum/projects/an-idea-for-soft-power-with-no-quiescent-loss/

[retrolefty]

Call me old school, but I always just used an inexpensive 5vdc single coil latching relay when I want or need manual on/auto off power control. Micro on startup just pulls a digital output pin low to latch power on and then brings the pin low when wishing to power off.

 http://img25.imageshack.us/img25/563/08miq7.jpg

[ludzinc]

Define 'no power'.

When you can sleep a micro and have it draw uA, which gives you YEARS of operation on a coin cell, do you really need to go to ZERO draw?