Battery supply for PIC18F458

flip · Joined: 15 Feb 2005 Posts: 11

I want my PIC18f458 to run on batteries, (two AA's (3V)), does anyone know what kind of circuit I will need or the best way to implement this?

I was told I will need a voltage regulator, to make the DC constant (even though I thought DC was constant), but I am not to sure what kind of voltage needs to supplied to the voltage regulator.

So if anyone can make a suggestion that would be great.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

If you're going to run off two 1.5v batteries, that's 3v, and you'll need
to the the 18LF458. The regular "F" chip won't run below 4.2v, according
to the data sheet.

I did a project which used a DC-DC boost converter. It ran off two
AA cells, so it started with a 3v input, and declined to about 2v over
the useful battery life. It put out a constant +3.3v to the 18LF458.
I used a T.I. TPS61107 for this.

But this is probably too complex for your project. It's probably easier
to just use the "LF" PIC. Also, you should run it at 4 MHz if you run
it off two batteries (which decline in voltage). See Figure 27-3 in
the 18F458 data sheet to see why I suggest this.