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Re: Why does Analog Multimeter need AAA Batery

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Posted by nicksanspam on February 28, 2005, 7:38 am

That might be an Insteon/X10 interface PIC...

The data sheet says it uses about 100 nanoamps at 3 V in sleep mode and
12 microamps at 32 kHz. If it's awake 1% of the time, say 1 second out of 100,
when it talks to a central controller, it would need 0.99x0.1+0.01x12 = 0.22
microamps. Q = 340C coulombs and I = 60Q = 0.22x10^-6 amps makes C = 10 pF,
theoretically-speaking :-)

If we needed more power and worried about overcharging the 2 AAAs, we might
use the PIC to measure the voltage and only enable the charge pump as needed.


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