• Power Up System without Battery

• Charge Faster than LinearChargers

• High-Accuracy Voltage and CurrentRegulation

• Input Current Regulation Accuracy: ±5% (100 mA and 500mA)

• Charge Voltage Regulation Accuracy: ±0.5% (25°C), ±1% (0°C to125°C)

• Charge Current Regulation Accuracy: ±5%

• Input Voltage Based Dynamic Power Management (VIN DPM)

• BadAdaptor Detection and Rejection

• Safety Limit Register for Maximum ChargeVoltage and Current Limiting

• High-Efficiency Mini-USB/AC Battery Charger forSingle-Cell Li-Ion and Li-Polymer Battery Packs

• 20-V Absolute Maximum InputVoltage Rating

• 6.5-V Maximum Operating InputVoltage

• Built-In Input Current Sensing andLimiting

• Integrated Power FETs for Up To 1.55-A Charge Rate

• Programmable Charge Parameters throughI2C? CompatibleInterface (up to 3.4 Mbps):

• Input Current Limit

• VIN DPMThreshold

• Fast-Charge/Termination Current

• Charge RegulationVoltage (3.5 V to 4.44 V)

• Low Charge Current ModeEnable/Disable

• Termination Enable/Disable

• Support up to 1.55A Charge Current using 55 mΩ SensingResistor

• Synchronous Fixed-Frequency PWM Controller Operating at 3 MHz With 0%to 99.5% Duty Cycle

• Automatic High Impedance Mode for Low Power Consumption

• Robust Protection

• Reverse Leakage Protection PreventsBattery Drainage

• Thermal Regulation and Protection

• Input/Output Overvoltage Protection

• Status Output for Charging and Faults

• USB Friendly Boot-UpSequence

• Automatic Charging

• Boost Mode Operation for USBOTG

• Input Voltage Range (from Battery): 3.2 V to 4.5V

• 2.1 mm x 2 mm 20-Pin WCSPPackage

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The bq24157 is a compact, flexible, high-efficiency, USB-friendly switch-mode chargemanagement device for single-cell Li-ion and Li-polymer batteries used in a wide range of portableapplications. The charge parameters can be programmed through an I2Cinterface. The IC integrates a synchronous PWM controller, power MOSFETs, input current sensing,high-accuracy current and voltage regulation, and charge termination, into a small WCSPpackage.

The IC charges the battery in three phases: conditioning, constant current and constantvoltage. The input current is automatically limited to the value set by the host. Charge isterminated based on battery voltage and user-selectable minimum current level. A safety timer withreset control provides a safety backup for I2C interface. During normaloperation, The IC automatically restarts the charge cycle if the battery voltage falls below aninternal threshold and automatically enters sleep mode or high impedance mode when the input supplyis removed. The charge status can be reported to the host using the I2Cinterface. During the charging process, the IC monitors its junction temperature(TJ) and reduces the charge current once TJ increasesto about 125°C. To support USB OTG device, bq24157 can provide VBUS (5.05 V) by boosting thebattery voltage. The IC is available in 20-pin WCSP package.