LT1239 Datasheet | Linear Technology

LT1239 Backup Battery Management Circuit Features s s s s s s s s s s s s DESCRIPTION The LT ® 1239 is a micropower backup battery management system for portable puters and instrumentation. It contains two regulators for regulating the battery voltage and memory voltage and a parator for switching between main power and backup power. The first regulator provides a constant voltage charge for the backup batteries and is adjustable from 3.75V up to 20V. An equalization amplifier bined with the first regulator provides precision charge equalization for a 2-cell lithium-ion system. A second regulator with 4.85V output provides a regulated backup battery voltage to the memory when main power is lost. The second regulator also isolates the backup battery from the main 5V supply during normal operation when the memory is being powered by the 5V supply. A parator is included which provides automatic switchover from main 5V power to backup power ensuring uninterrupted power for memory and power monitor, LTC and LT are registered trademarks of Linear Technology Corporation. Micropower Operation (IQ = 20µA) Adjustable Regulator for Battery Charging 4.85V Regulator for Battery Regulation Cell Voltage Equalization in 2-Cell Systems Low-Battery Detector Protects Lithium Cells parator for Automatic Power Switching Shutdown Output Current Sensing Current and Thermal Limiting Reverse Output Protection 16-Pin SO Package Operates on 7V to 30V Input U APPLICATIONS s s s Backup Battery Management Systems for Portable puters Lithium-Ion Backup Systems Ni Cd Backup Systems TYPICAL APPLICATION Lithium-Ion Backup System 10 INPUT 2 OUT 1 14 MAIN BATTERY PACK 7V TO 24V INPUT 1 REGULATOR #1 16 1 15 7 681k 1% 8 3.4V Li-Ion CELL 13 5V SYSTEM POWER 69.8k 1% 3.4V Li-Ion CELL 300p F ADJ IMON1 E/A (IN) INPUT 2 604k 1% 120Ω- 120Ω- + 22µF 3 SHDN1 - GND 2 IN LOW-BATTERY DETECT GND 4 GND INPUT 1 5 IN REGULATOR #2 OUT + E/A (OUT) 5VIN + - GND OUT 2 12 MEMORY POWER...