0100,0100,0100Thanks for all the useful comments on the 6V lithium. Perhaps I should explain a few things. The only reason why I'm using that particular battery is because it's long lasting, high capacity and readily available. I didn't choose it myself so maybe there are some good alternatives less than 5V and then I wouldn't use any regulation at all. I know there are 4.5V Duracel batteries (MN1203) that cavers use. Maybe if they had a 5 year shelf life that would be the answer. The circuit is a bait dispenser and will live in the bush, so solar is not an option. The battery has to be capable of supplying 3A in short 3 second bursts once in a while. The reason I was in a hurry is because prototypes had to be ready for a trial, but now that rush is over I have time to perfect the final version. I liked ArialMatt Pobursky's suggestion of that TI TPS7250 low drop out regulator except that its quiescent current is 180uA. My circuit draws 290uA on average so I think the two diodes would waste less energy (haven't done the sums). I see that it has a 0.5uA sleep state so maybe I could work out something there.0100,0100,0100Architect Paul Gaastra email:pgaastra@hortresearch.co.nz BioEngineering Technologies, HortResearch Private Bag 3123 phone +64 7 8584745 Hamilton, NEW ZEALAND fax +64 7 8584705 ______________________________________________________ The contents of this e-mail are privileged and/or confidential to the named recipient and are not to be used by any other person and/or organisation. If you have received this e-mail in error, please notify the sender and delete all material pertaining to this e-mail. ______________________________________________________ -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu