ICL7673 pdf datasheet

Automatic Battery Back-Up Switch
The Intersil ICL7673 is a monolithic CMOS battery backup
circuit that offers unique performance advantages over
conventional means of switching to a backup supply. The
ICL7673 is intended as a low-cost solution for the switching
of systems between two power supplies; main and battery
backup. The main application is keep-alive-battery power
switching for use in volatile CMOS RAM memory systems
and real time clocks. In many applications this circuit will
represent a low insertion voltage loss between the supplies
and load. This circuit features low current consumption, wide
operating voltage range, and exceptionally low leakage
between inputs. Logic outputs are provided that can be used
to indicate which supply is connected and can also be used
to increase the power switching capability of the circuit by
driving external PNP transistors.