KB4054

Programmable Charge Current Up to 600mA
No MOSFET, Sense Resistor or Blocking Diode Required
Complete Linear Charger in SOT Package for Single Cell Lithium-Ion Batteries
Constant-Current/Constant-Voltage Operation with Thermal Regulation to Maximize Charge Rate Without Risk of Overheating
Charges Single Cell Li-Ion Batteries Directly from USB Port
Preset 4.2V Charge Voltage with ±1% Accuracy
Charge Current Monitor Output for Gas Gauging
Automatic Recharge
Charge Status Output Pin
C/10 Charge Termination
25A Supply Current in Shutdown
2.9V Trickle Charge Threshold (KB4054)
Available Without Trickle Charge (KB4054X)
Soft-Start Limits Inrush Current
Available in SOT23-5 Package
Cellular Telephones, PDAs, MP3 Players
Charging Docks and Cradles
Bluetooth Applications

The KB 4054 is a complete constant-current/constantvoltage linear charger for single cell lithium-ion batteries. Its ThinSOT package and low external component count make the KB4054 ideally suited for portable applications. Furthermore, the KB4054 is specifically designed to work within USB power specifications.

No external sense resistor is needed, and no blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates the charge current to limit the die temperature during high power operation or high ambient temperature. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The KB4054 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached.

When the input supply (wall adapter or USB supply) is removed, the KB4054 automatically enters a low current state, dropping the battery drain current to less than 2A. The KB4054 can be put into shutdown mode, reducing the supply current to 25A.

Other features include charge current monitor, undervoltage lockout, automatic recharge and a status pin to indicate charge termination and the presence of an input voltage.