Electronic Design

Backup System Provides Charging and Control for Batteries

With a growing number of electrical systems that must remain active around the clock, it is important to implement high-efficiency backup power systems. To that end, Linear Technology has introduced the LTC4040, a backup power management system. The device is equipped with an on-chip bidirectional synchronous converter, which provides a seamless transition from input to backup power.

Operating on 3.5V to 5V supply rails, the LTC4040 leverages dual charging and control modes. When the system is connected to an external power source, it operates as a step-down battery charger for single-cell Li-Ion or LiFePO4 batteries. This design does not interfere with main supply rails, as the device gives priority to system load.

With input current monitoring and input power loss indicators, the LTC4040 immediately switches to backup control during a power failure. When the system drops below the power-fall input threshold, the device functions as a step-up regulator capable of delivering up to 2.5A. This two-way design is optimized for applications as diverse as security, communications, and industrial backup.

The LTC4040 supports eight selectable charge voltages for Li-Ion (ranging from 3.95V to 4.1V) and LiFePO4 (ranging from 3.45V to 3.6V) batteries. It comes with optional overvoltage protection, which protects the system from voltages greater than 60V. Operating within a temperature range of -40°C and 125°C, the LTC4040 features a low-profile package.

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