On Wed, Dec 15, 2010 at 12:32 AM, John Gardner wrote: > When all else fails, do it right :) > > What's the beef with switchers? > Couldn't have said it better myself. As for the beef with switchers, there's generally a higher part count associated with them. That's all. And it was hard to find one with the righ= t specifications. Even the TI one has a maximum input voltage of 5.5 volts. Now i'll need a CMOS comparator and a couple of power FETs to route current through a high power schottky/germanium diode with about a 0.3 forward volt drop if the battery voltage is greater than 5.5 volts. I don't think the battery pack will go above 5.8 volts at any point. I have no idea where to get a 5.5 volt voltage reference though. An LDO sounds good, but then it'll drop out before it reaches 5.5 volts. I'm thinking another solution would be to use a 5 volt LDO (low power), compare the 5 volts from there with the voltage from the raw battery pack through a resistor divider. I'd arrange the divider's output to be 5 volts when the battery pack voltage is 5.5 volts. Any higher, and the divider output would be greater than 5 volts and power would be routed through a power diode. Any less than 5.5 volts and the divider output would be less than 5 volts and the comparator would route current directly to the switching supply. I already am sampling the switching supply and some comparators from TI. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .