1 Features
1• Ideal For Highly Efficient Charger Designs For
Single-, Two-, or Three-Cell Li-Ion and Li-Polymer
Battery Packs
• bq24105 Also for LiFePO4 Battery (see Using
bq24105 to Charge the LiFePO4 Battery)
• Integrated Synchronous Fixed-Frequency PWM
Controller Operating at 1.1 MHz With 0% to 100%
Duty Cycle
• Integrated Power FETs for Up To 2-A Charge
Rate
• High-Accuracy Voltage and Current Regulation
• Available in Both Stand-Alone (Built-In Charge
Management and Control) and System-Controlled
(Under System Command) Versions
• Status Outputs for LED or Host Processor
Interface Indicates Charge-In-Progress, Charge
Completion, Fault, and AC-Adapter Present
Conditions
• 20-V Maximum Voltage Rating on IN and OUT userPins
• High-Side Battery Current Sensing
• Battery Temperature Monitoring
• Automatic Sleep Mode for Low Power
Consumption
• System-Controlled Version Can Be Used in NiMH
and NiCd Applications
• Reverse Leakage Protection Prevents Battery
Drainage
• Thermal Shutdown and Protection
• Built-In Battery Detection
• Available in 20-Pin, 3.50 mm × 4.50 mm VQFN
Package

2 Applications
• Handheld Products
• Portable Media Players
• Industrial and Medical Equipment
• Portable Equipment

3 Description
The bqSWITCHER™ series are highly integrated Li-
ion and Li-polymer switch-mode charge management
devices targeted at a wide range of portable
applications. The bqSWITCHER™ series offers
integrated synchronous PWM controller and power FETs, high-accuracy current and voltage regulation,
charge preconditioning, charge status, and charge
termination, in a small, thermally enhanced VQFN
package. The system-controlled version provides
additional inputs 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 userPins
selectable minimum current level. A programmable
charge timer provides a safety backup for charge
termination. The bqSWITCHER™ automatically
restarts the charge cycle if the battery voltage falls
below an internal threshold. The bqSWITCHER™
automatically enters sleep mode when VCC supply is
removed.