Description
The FAN5400 family (FAN540X) combines a highly integrated switch-mode charger, to minimize single-cell Lithium-ion (Li-ion) charging time from a USB power source, and a boost regulator to power a USB peripheral from the battery.
The charging parameters and operating modes are programmable through an I2C Interface that operates up to 3.4Mbps. The charger and boost regulator circuits switch at 3MHz to minimize the size of external passive components.
The FAN540X provides battery charging in three phases: conditioning, constant current, and constant voltage.

FEATUREs
■ Fully Integrated, High-Efficiency Charger for Single-Cell Li-Ion and Li-Polymer Battery Packs
■ Faster Charging than Linear
■ Charge Voltage Accuracy:   ±0.5% at 25°C
                                        ±1% from 0 to 125°C
■5% Input Current Regulation Accuracy
■5% Charge Current Regulation Accuracy
■ 20V Absolute Maximum Input Voltage
■ 6V Maximum Input Operating Voltage
■ 1.25A Maximum Charge Rate
■ Programmable through High-Speed I2C Interface (3.4Mb/s) with Fast Mode Plus Compatibility
   – Input Current
   – Fast-Charge / Termination Current
   – Charger Voltage
   – Termination Enable
■  3MHz Synchronous Buck PWM Controller with Wide Duty Cycle Range
■ Small Footprint 1H External Inductor
■ Safety Timer with Reset Control
■ 1.8V Regulated Output from VBUS for Auxiliary Circuits
■ Weak Input Sources Accommodated by Reducing Charging Current to Maintain Minimum VBUS Voltage
■ Low Reverse Leakage to Prevent Battery Drain to VBUS
■ 5V, 300mA Boost Mode for USB OTG for 2.5 to 4.5V Battery Input

APPLICATIONs
■ Cell Phones, Smart Phones, PDAs
■ Tablet, Portable Media Players
■ Gaming Device, Digital Cameras