Gennady Palitsky wrote:
>
> I am back with the question on PIC and power consumtion. I need to make
> measurements with PIC every 5 minutes, keeeping power consumption to the
> minimum between measurements. My first thought - to turn power to PIC
> off and to turn it on by external timer (what is 50-100 uA by itself).
> Does anybody know of better way to do it? And second - how can I keep
> track of what PIC is doing if I power it off and don't use NVRAM?

If the 5 minute period is flexible, the absolute minimum power can be
achieved with a few CMOS gates and a low-drop regulator.

Hook the low-drop on one of the gate outputs. Set up a slow charging
cap on the input. This will switch the PIC on every time the cap charged
up fully. You then switch the CMOS output off with an input coming from
the PIC.

You can drop from microamps to nanoamps this way. I've seen a wireless
alarm keypad designed like this, and its 9V battery lasts for
effectively the shelf life of such a battery.

--
Friendly Regards

Tjaart van der Walt
mailto:tjaart@wasp.co.za
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