piclist 1999\10\15\110101a >
Thread: Low current power for a PIC
face BY : Jim Hartmann email (remove spam text)

A couple of ideas:
1. Use a  pre-regulator to a low drop out regulator to get the Vin low
2. Use LP mode xtal oscillator to lower operating current.

Chris Eddy <spam_OUTceddyEraseMEspamspam_OUTNB.NET>EraseMEspamspam_OUTMITVMA.MIT.EDU> on 10/15/1999 09:30:18 AM

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Subject:  Low current power for a PIC


I have a PIC that must live off of a 220uF cap for 7 seconds.  I can get
the PIC to consume low power, but I am having trouble getting the
regulator designed.  The 78L05 sucks 2-3mA Q current, way too much.
Looking for 50-100uA.  The low dropout regs are neat, but they have a
very limitted Vin max.  I need 30V.  I built a pass regulator with a
res, zener, and NPN trans, which meets my goals, but since the current
through the zener is low, then as the V on the C drops off, then the V
on the zener drops off, and the V on the PIC droops as well.  This
causes the RC osc to skew, and my highly important timer gives me
predictable garbage!

Any great ideas?

Chris Eddy
Pioneer Microsystems, Inc.


See also: www.piclist.com/techref/power.htm?key=power
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