PICers ... I have a bit of a dilemma selecting an IR sensor.  They're NaPion
motion sensors that are made by Matsushita. They come in both digital and
analgue o/p: it's digital that I need. I've used them before and they're pretty
damn good.

The one's I'm talking about are here -->
http://pewa.panasonic.com/pcsd/product/sens/select_motion.html

The dilemma -->
They come in a standard version that works on 5V but its quiescent drain is
170uA to 300uA

However, they now offer an ultra-low standby current version that's rated at 46
to 60 uA quiescent.

That's MUCH better for a battery operated device. BUT, the ultra-low Iq version
only works on 3V.

Okaaaay, I have a 12V, 7.5Ah system and the PIC's (16F84) voltage is regulated
down to 5V using a 78LS05. Not sure what its standby drain is but must be
pretty low as the battery lasts for weeks.

The QUESTION: what ultra-low Iq 3V regulators come to mind?

If I go with the 3V sensor, I'd have to drop 2V off the 5V rail or 9V off the
12V rail. This when I'm pulling, hopefully, total standby current of <150uA
(inc. both regulators, the PIC in sleep mode and the IR sensor)

What would people say is the best way to go? 

These sensors aren't all that cheap and I need about 6, so I probly want to get
it right first time. :(

Thanks in advance for advice.

Best - Debbie :)

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