DESCRIPTION
The LTC®1559 is a backup battery controller that provides all the functions necessary to implement a backup 3.3V or 5V power supply using a single NiCd cell. It includes a 1.2V to 3.07V/4.63V boost converter, an intelligent 2-stage battery charger, automatic backup switching and a microprocessor reset generator. The boost converter uses a synchronous switching architecture to achieve a typical efficiency of 70%, ensuring maximum backup lifetime from a small NiCd cell.

FEATURES
■ Complete Battery Backup System in an SO-8, 16-Pin GN or SO Package
■ Generates Fixed Backup Voltage (3.07V/4.63V) from a Single 1.2V NiCd Button Cell
■ Automatic Main Supply to Backup Switching
■ Minimum 100mW Output Power
■ Automatic Fast Recharge of NiCd Battery
■ Programmable NiCd Trickle Charge Current
■ Smart NiCd Charger Minimizes Recharge Time and Maximizes System Efficiency After Backup
■ Onboard Power-Up and Push-Button Reset Generator
■ Performs VCC Supervisory Functions
■ Reset Assertion Guaranteed at VCC = 1V
■ Short-Circuit Protection
■ Thermal Limiting

APPLICATIONS
■ Notebook Computers
■ Palmtop Computers/PDAs
■ Portable Instruments
■ Battery-Powered Systems