AVR-Chat

David VanHorn wrote:
> At 05:09 PM 3/14/2004 -0800, jay marante wrote:
>
>> isn't the back-up battery always conducting on that state even if
>> the main power is on?
>
> No, the diode in series with the battery is reverse-biased.
>
> If the backup is a lithium, you need dual diodes, or a current
> limiting scheme to some very small current, so that a single
> component failure won't give you an exploding lithium battery.


That's another point.
If backup usage current is below 500mA, then use plain and cheap Alkaline
ones.
They are safe, shelf life is much longer than anything else.
Of course, lithium current limit is a good idea, perhaps a small fuse? :)


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