'Battery Charger' related articles 1

  1. 2008/07/23 KB4540 - Li-Ion Battery Charger
DESCRIPTION
The KB 4540 is a complete constant-current/constantvoltage linear charger for single cell lithium-ion batteries.
Its ThinSOT package and low external component count make the KB4540 ideally suited for portable applications.
Furthermore, the KB4540 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 KB4540 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 KB4540 automatically enters a low current state, dropping the battery drain current to less than 2μA.
The KB4540 can be put into shutdown mode, reducing the supply current to 25μA.
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.

FEATURES
* Programmable Charge Current Up to 800mA
* 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
* 25μA Supply Current in Shutdown
* 2.9V Trickle Charge Threshold (KB4540)
* Available Without Trickle Charge (KB4540X)
* Soft-Start Limits Inrush Current
* Available in SOT23-5 Package

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