On 27/05/2011 10:07, David wrote:
> All,
>
> I am building a small PIC based IR sender which will attach to a
> moving object.
>
> As there is no power source it will have to be battery powered.  I was
> thinking of 3 AA batteries with an in-circuit charger.  The IR LED has
> a Vfwd of 1.5v, I can pick a PIC that will operate at 3v.
>
> So two easy questions:
>
> 2) Is there anything better than simple AA batteries?
>
> 3) Recommendations for your favourite battery charge IC, so I can go goog=
le.
>

It would be useful to know roughly what your expected (average - e.g. if=20
circuit will sleep/wake up) current draw will be. Depending on this and=20
how long it might be left unattended would help with deciding on=20
chemistry (i.e. do you need low self discharge, quick charging, high=20
current capability, etc)
3 AAs would be cheap and readily available. Depending on current=20
requirements you might want to use 3xAAA instead. Or as Michael=20
mentioned 1 or 2 AA/AAA with step up.
A Li-Ion is another option, there are lots of dedicated charging ICs=20
available - type "Li-Ion charge controller into Digikey/RS etc, and you=20
will have plenty of options turn up.
One chip that comes to mind for Li-Ion is the Microchip MCP73811 which=20
is cheap and easy to use (there are a few MCP738xx versions)
Another one is the LTC4054, similar to the above.
Note that neither of these have a temperature sense pin which you might=20
want to use in your application.




--=20
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