Features

■ Low power PFM boost regulator

■ Input voltage range is from 1.6V to 4.5V

■ Output voltage range is from 3V to 5V

■ 500mA maximum load current capability

■ 95% efficient power conversion

■ 2-3 cell and single cell Li-Ion systems

■ Variable on-time Pulse Frequency Modulation (PFM)

■ Internal synchronous rectifier (no need for external diode)

■ Low-battery detection

■ Logic controlled shutdown with true-load disconnect

■ Low (80μA) quiescent current

■ TSSOP-8 Package

Applications

■ DSCs

■ PDAs

■ Cell phones, smart phones

■ Portable instrumentations

■ 2-3 AA / AAA cells operated devices

■ Single cell Li-Ion operated devices

General Description

The FAN4855 is a low power boost regulator designed for low voltage DC to DC conversion in 2-cell battery powered systems such as digital cameras, cell phones and PDAs. The converter starts-up at 1.3V and operates after the start at an input voltage as low as 1V. Output voltage can be adjusted by external resistors from 3.3V to 5V with a maximum load current of 0.5A. Quiescent current in shut-down mode is less than 10μA, which maximizes the battery live time. The ON time changes with the input voltage to maintain the ripple current constant and to provide the highest efficiency over a wide load range—while maintaining low peak currents in the boost inductor. The combination of built-in power transistors, synchronous rectification and low supply current, make the FAN4855 ideal for portable applications. The FAN4855 is available in 8-lead TSSOP package.