SMB239

http://www.summitmicro.com/

2129 3.0 2/23/2009

1

INTRODUCTION

• World’s smallest linear charger

•

Linear charging for reduced board space

o

Up to 525mA charge current

o

Stable with small ceramic capacitors

• 4.35 to 6.5V input voltage range

• High-accuracy output voltage regulation: 1%

• Low reverse leakage current

interface and lockable non-volatile memory

o

Battery voltage set point

o

Pre-charge, fast charge, termination current

o

Fast charge voltage threshold

o

Temperature limits

o

Charge safety timers

o

Automatic restart threshold

• Fault/Status indicator

• Wide range of protection features

o

Thermal regulation

o

Battery pack temperature monitor

o

Input/output over-voltage lockout

Applications

• Bluetooth & Stereo Headsets

• Noise Cancellation Headphones

• Wireless Handsets

• MP3 Players

• Wrist PDA/Watches

• Handheld Equipment

The SMB239 is a programmable single-cell lithium-ion/lithium-polymer

battery charger for a variety of portable applications.

The device

provides a simple way to charge low- and medium-capacity Li-Ion or

Li-Polymer batteries via a USB port or an AC port. Unlike conventional

devices, the SMB239’s very small package and high level of

configurability simplify design in a wide range of handheld equipment.

Charge control includes qualification, trickle-charge, pre-charge,

constant current/constant voltage, and termination/safety settings that

are fully programmable via a serial I2C/SMBus making the device truly

a flexible solution. Pre-charge, fast charge and termination current

levels can be set via I2C commands. The SMB239 offers the option to

automatically recharge the battery upon power cycling, only when

battery voltage falls 220/390/550mV below the selectable float voltage.

This allows for a reduced number of charge/discharge cycles, thereby

extending battery life.

The SMB239 offers a wide variety of features that protect the battery

pack as well as the charger and input circuitry: over-current, under-

and over-voltage, and thermal protection. Ultra-precise, 1% accurate,

float voltage control improves battery capacity utilization. Status can

be monitored via the serial port for charge state and fault conditions.

In addition, one LED driver output can be used to signal charge status.

As a protection mechanism, when the junction temperature

approaches approximately 110

°C, the SMB239 will start to reduce

charge current to ensure device and system reliability, while charging

the battery cell as fast as possible.

The SMB239 is available in a space-saving, 1.3mm x 2.1mm uCSP

TM

package with lead-free balls and is rated over the –30

°C to +85°C

temperature range.

Figure 1 – Applications block diagram featuring the SMB239 programmable linear battery charger.

SIMPLIFIED APPLICATIONS DRAWING

FEATURES & APPLICATIONS

4.35V to 6.5V

10V Tolerance

GND

STAT

RLIM

RED

LED

OUT

1-cell

Li+ Battery

SCL

BATT

4.7uF

SDA

4.7uF

SMB239

Up to 525mA

Charge Current

Battery

OVLO

I2C Communication

THERM

IN