INTRODUCTION

The SMB138 is a programmable single-cell lithium-ion/lithium-polymer battery charger designed for a variety of portable applications. The device provides a simple and efficient way to charge high-capacity LiIon batteries via a USB or AC adapter input. Unlike conventional devices, the SMB138’s high-efficiency, switch-mode operation eliminates the thermal problems of conventional linear solutions. Also the buck converter architecture effectively multiplies the input current to increase charge rate for the Li+ cell and uses current limited supplies like USB more efficiently. The SMB138 also supports USB On-the-Go devices by providing the required USB-OTG +5V power supply using the Li-Ion battery as a source.

FEATURES & APPLICATIONS

• USB or AC input with programmable input current limiting

• Up to 1.25A continuous charging current from AC adapter

• Up to 750mA charging current from 500mA USB port using automatic TurboCharge™ mode

• +4.35 to +6.2V input voltage range (+16V tolerant)

• Two product options:

   o SMB138A: charger off until I2C command initiation, enable/disable control via I2C

   o SMB138C: charger powers up in charging mode, enable/disable control via I2C

• USB “On-the-Go” Power support for USB OTG enabled devices (+5V reverse output @ 200mA)

• Reverse current blocking (<5uA)

• High-efficiency 3MHz voltage-mode step-down regulator

• Integrated frequency compensation

• Internal power MOSFETs and precision current sensing

• High-accuracy float voltage regulation: 1%

• Thermal regulation (current foldback)

• Trickle charging

• Pre-charge and complete-charge (36/240min) safety timers

• Digital programming of all major parameters via I2C interface

   o Fast charge voltage threshold, float voltage

   o Pre-charge, fast charge, termination current

• Status register monitors and flags charger operation

   o Charge in-progress/termination

   o Charge timer fault

   o OC/UV/OV detection/shutdown

• uCSP-19 lead-free package (0.4mm ball pitch)

Applications

• 2.5/3/3G+ GSM/CDMA/WCDMA Phones

• Smartphones/PDAs

• Portable Media Players

• Portable GPS Terminals