The bq24155 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 I2C interface. The bq24155 integrates a synchronous PWM controller, power FETs, input current sensing, high-accuracy current and voltage regulation, and charge termination, into a small WCSP package.

The bq24155 charges the battery in three phases: conditioning, constant current and constant voltage. The input current is automatically limited to the value set by the host. Charge is terminated based on user-selectable minimum current level. A safety timer with reset control provides a safety backup for I2C interface. During normal operation, bq24155 automatically restarts the charge cycle if the battery voltage falls below an internal threshold and automatically enters sleep mode or high impedance mode when the input supply is removed. The charge status is reported to the host using the I2C compatible interface.

During the charging process, the bq24155 monitors its junction temperature (TJ) and reduces the charge current once TJ increases to approximately 125°C. The bq24155 is available in 14-pin QFN package.

• 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-125°C)
  • Charge Current Regulation Accuracy: ±5%
• 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-V Maximum Operating Input Voltage
• Built-In Input Current Sensing and Limiting
• Integrated Power FETs for Up To 1.25-A Charge Rate
• Programmable Charge Parameters through I2C Compatible Interface (up to 3.4 Mbps):
  • Input Current
  • Fast-Charge/Termination Current
  • Charge Voltage (3.5 V to 4.44 V)
  • Safety Timer with Reset Control
  • Termination Enable
• 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
• Power Up System without Battery
• 3.5 mm x 3.5 mm 14-Pin QFN Package
• APPLICATIONS
  • Mobile and Smart Phones
  • MP3 Players
  • Handheld Devices