[EE] Options for automated zero power shutdown?

[Art]

Hi All,

My project is nearing fruition, but I'd like to avoid the 25uA (leakage)
current consumption in order to keep the battery as small and light as
possible.

I'd like something that works automatically, as I might forget to turn a
manually operated switch off.

I have multiple logic level outputs that can be used, ~2 hours (+/- 1
hour) after the last L to H transition, the power from the battery
disconnects.

To restore the power, existing switches on the PIC inputs are pulled low
on closure, can this logic level zero be used to restore power?

I know it is common practice to use a cap on a mosfet gate to switch the
power off, but many mosfets will latch up, so a schmidt gate is needed.
Is there a better/simpler way?

My board space, and area inside the enclosure is very limited, as is the
battery size...so the solution needs to be compact and draw near zero
battery current.

Suggestions? TY all input.

Art

[Isaac M. Bavaresco]

Art,


Check this:
<http://www.piclist.com/techref/member/IMB-yahoo-J86/power-on-off.htm>


If your MCU doesn't have an open-drain output just use an additional NPN
transistor.


Cheers,

Isaac

Post by Art
Hi All,
My project is nearing fruition, but I'd like to avoid the 25uA (leakage)
current consumption in order to keep the battery as small and light as
possible.
I'd like something that works automatically, as I might forget to turn a
manually operated switch off.
I have multiple logic level outputs that can be used, ~2 hours (+/- 1
hour) after the last L to H transition, the power from the battery
disconnects.
To restore the power, existing switches on the PIC inputs are pulled low
on closure, can this logic level zero be used to restore power?
I know it is common practice to use a cap on a mosfet gate to switch the
power off, but many mosfets will latch up, so a schmidt gate is needed.
Is there a better/simpler way?
My board space, and area inside the enclosure is very limited, as is the
battery size...so the solution needs to be compact and draw near zero
battery current.
Suggestions? TY all input.
Art

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