Powering the board with a battery

[reneec]

Hi - I'm a bit new to this... what's the best way to power the board with a battery?

Thanks.

renee

[dyeatman]

It would be nice to know what board, what PIC and what battery!!!
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[reneec]

Right... sorry about that. :-)

It's the PIC18F8722 development kit that I'm working with. There's a connection for the ac/dc adapter (9v) - but I haven't found a battery pack/connector that works with it.

[Ttelmah]

Funnily enough, a lot more to this, than it sounds!....

Cheapest. If you go for some of the PICs supporting higher supply voltages, you can use a completely unregulated pack like 4*1.5v batteries.
Similarly for low voltage devices, one of the Lithium 3v batteries directly powering a low power device (common solution for things like remote controls).
Then use a higher voltage (9v), and a simple linear regulator. To save power, first go for the regulators which themselves draw less power, then consider 'switching regulators'. Downsides of the later, more parts, and risk of noise. Plusses very high efficiency.
Then, as an alternative, consider 'boost' regulators from a single cell.

Commercially, there are as many solutions, as days in a year....

The balances are between:
Battery costs
Circuit costs
Electrical noise
Efficiency
etc..

I'd guess that the 'commonest', and simplest for most people, is to choose a battery voltage above the required operation, and go with the simple linear regulator.

Best Wishes

[bkamen]

If I were building a battery power app, I would have to ask first if noise is a concern.

This can answer the problem of Linear vs Switching regulators. (I had one project that needed 9 volts for an RF transmitter. So 12V was available right there -- and noise was an issue.)

If the project could allow switching regulators, the there are all sorts of fun solutions.

You can generate 3.3v from a single 1.5V alkaline. (and it's regulated!)

So there's some questions you need answered first...

Linear, Maxim, National Semi --- all make nice DC-DC converters.

-Ben
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[Ttelmah]

Now we know what board is involved, first a comment. These boards are designed for basic testing and development. Basic 'assumption', is that this will be on a test bench, not in the field, so battery power is not really considered.
You will not find any 'off the shelf' pack, you will need to put one together yourself. However it is not hard. the board has a simple linear regulator (LV7805). It expects something 'around' 9v, but won't be worried by a little more, or less (say 7 to 11v). Go much higher, and depending on what else you are running from it, the regulator may get too hot....
Since the board is not designed for low consumption, I'd suggest a pack of 6 D-cells, which wired to a suitable plug will run this fine, and be large enough to run it for a reasonably long time.
Packs this size, are available from RC model shops, but will be 'bare wire' ended.

Best Wishes