The KF4055 is a complete constant-current/constant-voltage linear charger for single cell lithium-ion batteries. Its package and low external component count make the KF4055 ideally suited for portable applications. Furthermore, the KF4055 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. The charge voltage is fixed at 4.2V, and the charge current can be programmed externally with a single resistor. The KF4055 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached.
The KF4055 converters are available in the industry standard SOT23-5L power packages
Features
Programmable Charge Current up to 700mA.
No MOSFET, Sense Resistor or Blocking Diode Required.
Constant-Current/Constant-Voltage Operation
with Thermal Regulation to Maximize Charge Rate.
Charges Single Cell Li-lon Batteries Directly from USB Port。
Preset 4.2V Charge Voltage with 1% Accuracy.
Automatic Recharge。
2.9V Trickle Charge Threshold.
SOT23-5L Package.
Application
Charger for Li-lon Coin Cell Batteries.
Portable MP3 Players, Wireless Headsets。
Bluetooth Applications.
Multifunction Wristwatches。