FAN5400/FAN5401/FAN5402/ FAN5403/ FAN5404/ FAN5405
USB-Compliant Single-Cell Li-Ion Switching Charger with
USB-OTG Boost Regulator
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 1H 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
Cell Phones, Smart Phones, PDAs
Tablet, Portable Media Players
Gaming Device, Digital Cameras
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.
To ensure USB compliance and minimize charging time, the
input current is limited to the value set through the I2C host.
Charge termination is determined by a programmable
minimum current level. A safety timer with reset control
provides a safety backup for the I2C host.
The integrated circuit (IC) automatically restarts the charge
cycle when the battery falls below an internal threshold. If the
input source is removed, the IC enters a high-impedance
mode with leakage from the battery to the input prevented.
Charge status is reported back to the host through the I2C
port. Charge current is reduced when the die temperature
The FAN540X can operate as a boost regulator on
command from the system. The boost regulator includes a
soft-start that limits inrush current from the battery.
The FAN540X is available in a 1.96 x 1.87mm, 20-bump,
0.4mm pitch WLCSP package.
SW L1 1H
All trademarks are the property of their respective owners.
Figure 1. Typical Application (FAN5403-05 Pin Out)
© 2009 Fairchild Semiconductor Corporation
FAN5400 Family • Rev. 1.0.7