SLUU200 − July 2004
4
Using the bq241xx (bqSWITCHER
E
)
Using the bq241xx (bqSWITCHER
E
)
.
Portable Power
Contents
1
Introduction
4
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2
Test Summary
5
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3
Schematic
6
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4
Physical Layouts
8
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5
List of Materials
11
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6
References
15
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1
Introduction
This user’s guide describes the bq241xxEVM (bqSWITCHER) Evaluation Module. The EVM provides a
convenient method for evaluating the performance of a charge management solution for portable applications
using the bq241xx product family. A complete designed and tested charger is presented. The charger is
designed to deliver up to 2.0 A of continuous output current. The charger is programmed from the factor to deliver
1.33 A of charging current. Follow the instructions in this user’s guide that pertain to the specific bq241xxEVM
to be evaluated (one-, two- or three-cell). Please refer to the bqSWITCHER data sheet (SLUS606) prior to
evaluation for detailed information on the bqSWITCHER device.
1.1
Background
The bqSWITCHER
series are highly integrated Li-Ion and Li-Pol switch-mode charge management devices
targeted at a wide range of portable applications. The bqSWITCHER series offer integrated synchronous PWM
Controller and PowerFETs, high-accuracy current and voltage regulation, charge conditioning, charge status,
and charge termination, in a small thermally enhanced QFN package. The system-controlled version provides
additional input for full charge management under system control.
The bqSWITCHER charges the battery in three phases: conditioning, constant current and constant voltage.
Charge is terminated based on user-selectable minimum current level. A programmable charge timer provides
a backup safety for charge termination. The bqSWITCHER automatically restarts the charge if the battery
voltage falls below an internal threshold. The bqSWITCHER automatically enters sleep mode when V
CC
supply
is removed.
