AN137 Datasheet, PDF (1/36 Pages) Silicon Laboratories – LITHIUM ION BATTERY CHARGER USING C8051F300

AN137
LITHIUM ION BATTERY CHARGER USING C8051F300
Relevant Devices
Key Points
This application note applies to the following devices: ^•
C8051F300
Introduction
Driven by the need for untethered mobility and
ease of use, many systems rely on rechargable bat- •
teries as their primary power source. The battery
charging circuitry for these systems is typically
implemented using a fixed-function IC to control •
the charging current/voltage profile.
The C8051F30x family provides a flexible alterna-
tive to fixed-function battery chargers. This appli-
cation note discusses how to use the C8051F30x ^•
family in Li-Ion battery charger applications. The
Li-Ion charging algorithms can be easily adapted to
other battery chemistries, but an understanding of
other battery chemistries is required to ensure
proper charging for those chemistries.
On-chip high-speed, 8-bit ADC provides supe-
rior accuracy in monitoring charge voltage
(critical to prevent overcharging in Li-Ion
applications), maximizing charge effectiveness
and battery life.
On-chip PWM provides means to implement
buck converter with a very small external
inductor.
On-chip Temp sensor provides an accurate and
stable drive voltage for determining battery
temperature. An external RTD (resistive tem-
perature device) can also be used via the flexi-
ble analog input AMUX.
A single C8051F30x platform provides full
product range for multi-chemistry chargers,
expediting time to market and reducing inven-
tory.
Rev. 1.2 12/03
Figure 1. Lithium Ion Battery Charge Block Diagram.
V Pos (+)
LDO
Buck
Converter
V Neg (-)
LED
8051F30x
Cygnal
Integrated
Products
PWM Out
AIN
8k FLASH, PWM,
Temp Sensor,
Precision Time Base
Resistor
Divider
Sense Resistor
Li-Ion
Cells
Copyright © 2003 by Silicon Laboratories
AN137-DS12