Hi John,

I have just been spending hours going over Linear's web site looking for
regulators for my power supply needs.

Check out
http://www.linear.com/prod/datasheet?datasheet=441&product_family=power . It
seems to be an example of what other people who posted before me are
referring to. 1.5v from one battery in -> regulated 3.3v out.  They have
lots of variations (5V out for example). The top of the power product tree
is here http://www.linear.com/prod/pft.html (to find other devices similar
to the one above.


New, Related Question:
Do you have to be more concerned with EMI when you use a switching DC-DC
convert / regulator?  I am considering this linear device
http://www.linear.com/prod/datasheet?datasheet=569&product_family=power
In a nutshell its 5V in, -12V @150ma out.  Its overkill for what I need (2ma
at -12V for an LCD), but the chip is only a couple bucks, and I am afraid of
discrete components:)

The data sheet actual has a sample board layout, warning, "If you don't lay
out your PCB carefully, its not going to work".

Is this normal?  Are switching regulators trickier to work with?  I gather
that a DC-DC convert is similar to a switching regulator; the difference
being that the output of the DC-DC convert will vary with changes in Vin. Is
that correct?

--BobG

> > -----Original Message-----
> > From: pic microcontroller discussion list
> > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of John Waters
> > Sent: Sunday, July 22, 2001 12:18
> > To: PICLIST@MITVMA.MIT.EDU
> > Subject: [OT]: How to reduce power consumption for battery operated
> > circuits?
> >
> >
> > Hi All,
> >
> > For a battery operated circuit, we want the power consumption to be as
low
> > as possible, but if the circuit involves a microcontroller, we will need
a
> > voltage regulator like the 78L05 or 7805 to keep the 5V stable. Since
the
> > supply voltage is at least 2V higher than the 5V, part of the current
will
> > be bypassed through the regulator, in other words, the regulator
> > "consumes"
> > some power even when there is no or little current demanding by the
> > microcontroller circuit itself.
> >
> > Is using the regulator unavoidable? What is the usual methods to reduce
> > power consumption for a battery operated microcontroller circuit?
> >
> > Thanks in advance!
> >
> > John
> >
> >
> >
> >
> >
> > _________________________________________________________________
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