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The bqSWITCHER™ series are highly integrated Liion 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 QFN package. The bqSWITCHER charges the battery in three phases: conditioning, constant current, and constant voltage. Charge is terminated based on userselectable 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 the CC supply voltage (V_CC) is removed. The bqSWITCHER™ supports a precision Li-ion or Li-polymer charging system for one-, two-, or three-cell applications. The bq24105 provides an integrated fixed 1MHz frequency voltage-mode controller with Feed-Forward function to regulate charge current or voltage. This type of controller is used to help improve line transient response, thereby simplifying the compensation network used for both continuous and discontinuous current conduction operation. The voltage and current loops are internally compensated using a Type-III compensation scheme that provides enough phase boost for stable operation, allowing the use of small ceramic capacitors with very low ESR. There is a 0.5-V offset on the bottom of the PWM ramp to allow the device to operate between 0% to 100% duty cycle. The internal PWM gate drive can directly control the internal PMOS and NMOS power MOSFETs. The high-side gate voltage swings from the CC supply voltage (V_CC) (when off), to V_CC - 6 V (when on and

• Qualified for Automotive Applications
• Ideal For Highly Efficient Charger Designs For Single-, Two-, or Three-Cell Li-Ion and LiPolymer Battery Packs
• Also for LiFePO₄ Battery (see Using bq24105 to Charge 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
• Stand-Alone (Built-In Charge Management and Control) Version 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 Pins
• High-Side Battery Current Sensing
• Battery Temperature Monitoring
• Automatic Sleep Mode for Low Power Consumption
• Reverse Leakage Protection Prevents Battery Drainage
• Thermal Shutdown and Protection
• Built-In Battery Detection
• Available in 20-Pin, 3.5 mm×4.5 mm, QFN Package