1 Features 1• Power Up System without Battery • Charge Faster than Linear Chargers • High-Accuracy Voltage and Current Regulation – Input Current Regulation Accuracy: ±5% (100 mA and 500 mA) – Charge Voltage Regulation Accuracy: ±0.5% (25°C), ±1% (0°C to 125°C) – Charge Current Regulation Accuracy: ±5% • Input Voltage Based Dynamic Power Management (VIN DPM) • Bad Adaptor Detection and Rejection • Safety Limit Register for Maximum Charge Voltage and Current Limiting • High-Efficiency Mini-USB/AC Battery Charger for Single-Cell Li-Ion and Li-Polymer Battery Packs • 20-V Absolute Maximum Input Voltage Rating • 6.5-V Maximum Operating Input Voltage • Built-In Input Current Sensing and Limiting • Integrated Power FETs for Up To 1.55-A Charge Rate • Programmable Charge Parameters through I 2C™ Compatible Interface (up to 3.4 Mbps): – Input Current Limit – VIN DPM Threshold – Fast-Charge/Termination Current – Charge Regulation Voltage (3.5 V to 4.44 V) – Low Charge Current Mode Enable/Disable – Termination Enable/Disable • Support up to 1.55A Charge Current using 55 mΩ Sensing Resistor • 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 Prevents Battery Drainage – Thermal Regulation and Protection – Input/Output Overvoltage Protection • Status Output for Charging and Faults • USB Friendly Boot-Up Sequence • Automatic Charging • Boost Mode Operation for USB OTG – Input Voltage Range (from Battery): 3.2 V to 4.5 V • 2.1 mm x 2 mm 20-Pin WCSP Package 2 Applications • Mobile and Smart Phones • MP3 Players • Handheld Devices 3 Description The bq24157 is a compact, flexible, high-efficiency, USB-friendly switch-mode charge management device for single-cell Li-ion and Li-polymer batteries used in a wide range of portable applications. The charge parameters can be programmed through an I 2C interface. The IC integrates a synchronous PWM controller, power MOSFETs, input current sensing, high-accuracy current and voltage regulation, and charge termination, into a small WCSP package.