AC power-to-backup battery switching IC

Thread Starter


Joined Feb 24, 2011
I am currently working on a project where I have a standard AC/DC converter (120VAC to 24VDC/100W/4A) and a separate 24VDC backup battery pack. I am looking for an IC to switch the power (uninterrupted) to the battery when the AC/DC power supply is removed. I have found several MOSFET and voltage regulating based ICs however, the rated voltage(s) and current(s) are far to low for my application. Does anybody know of a suitable switch for my application?



Joined May 9, 2009
Have a look at MAX17005B. It's a battery charger, but more importantly, the application circuit (pg. 10) shows a simple MOSFET auto-swap configuration which seems like it would be independent of supply voltage. Vgs of a MOSFET can't exceed ±20V, but I suspect a voltage divider on that pin will take care of that. As it is based around discrete components, it's likely to switch in the order of nanoseconds, though a small capacitor on the output would be advisable to provide a good hold-up source. Design it for a few milliseconds worst-case.