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.

Features

• Automatically Connects Output to the Greater of Either

Input Supply Voltage

• If Main Power to External Equipment is Lost, Circuit Will

Automatically Connect Battery Backup

• Reconnects Main Power When Restored

• Logic Indicator Signaling Status of Main Power

• Low Impedance Connection Switches

• Low Internal Power Consumption

• Wide Supply Range: . . . . . . . . . . . . . . . . . . . 2.5V to 15V

• Low Leakage Between Inputs

• External Transistors May Be Added if Very Large

Currents Need to Be Switched

• Pb-Free Plus Anneal Available (RoHS Compliant)

Applications

• On Board Battery Backup for Real-Time Clocks,

Timers, or Volatile RAMs

• Over/Under Voltage Detector

• Peak Voltage Detector

• Other Uses:

- Portable Instruments, Portable Telephones, Line

Operated Equipment