BQ24079

USB 供能的 1.2A 锂离子电池充电器和具有 4.1 VBAT 的电源路径管理 IC

The bq2407x series of devices are integrated Li-Ion linear chargers and system power path management devices targeted at space-limited portable applications. The devices operate from either a USB port or an AC adapter and support charge currents up to 1.5 A. The input voltage range with input overvoltage protection supports unregulated adapters. The USB input current limit accuracy and start up sequence allow the bq2407x to meet USB-IF inrush current specifications. Additionally, the input dynamic power management VIN-DPM prevents the charger from crashing incorrectly configured USB sources.

The bq2407x features dynamic power path management DPPM that powers the system while simultaneously and independently charging the battery. The DPPM circuit reduces the charge current when the input current limit causes the system output to fall to the DPPM threshold; thus, supplying the system load at all times while monitoring the charge current separately. This feature reduces the number of charge and discharge cycles on the battery, allows for proper charge termination and enables the system to run with a defective or absent battery pack.

Additionally, the regulated system input enables instant system turn-on when plugged in even with a totally discharged battery. The power-path management architecture also lets the battery supplement the system current requirements when the adapter cannot deliver the peak system currents, thus enabling the use of a smaller adapter.

The battery is charged in three phases: conditioning, constant current, and constant voltage. In all charge phases, an internal control loop monitors the IC junction temperature and reduces the charge current if the internal temperature threshold is exceeded. The charger power stage and charge current sense functions are fully integrated. The charger function has high accuracy current and voltage regulation loops, charge status display, and charge termination. The input current limit and charge current are programmable using external resistors.

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Fully Compliant USB Charger

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Selectable 100-mA and 500-mA Maximum

Input Current

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100-mA Maximum Current Limit Ensures

Compliance to USB-IF Standard

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Input-Based Dynamic Power Management

VIN-DPM for Protection Against Poor USB

Sources

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28-V Input Rating with Overvoltage Protection

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Integrated Dynamic Power Path Management

DPPM Function Simultaneously and

Independently Powers the System and Charges

the Battery

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Supports up to 1.5-A Charge Current with

Current Monitoring Output ISET

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Programmable Input Current Limit up to 1.5 A for

Wall Adapters

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System Output Tracks Battery Voltage bq24072

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Programmable Termination Current bq24074

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Battery Disconnect Function with SYSOFF Input

bq24075, bq24079

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Programmable Pre-Charge and Fast-Charge

Safety Timers

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Reverse Current, Short-Circuit and Thermal

Protection

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NTC Thermistor Input

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Proprietary Start-up Sequence Limits Inrush

Current

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Status Indication – Charging/Done, Power Good

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APPLICA ONS

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Smart Phones

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Portable Media Players

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Portable Navigation Devices

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Low-Power Handheld Devices

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