Dual Input USB/AC Adapter Standalone Li-Ion Battery Chargers

The LTC4075/LTC4075X are standalone linear chargers that are capable of charging a single-cell Li-Ion battery from both wall adapter and USB inputs. The chargers can detect power at the inputs and automatically select the appropriate power source for charging.

No external sense resistor or blocking diode is required for charging due to the internal MOSFET architecture. Internal thermal feedback regulates the battery charge current to maintain a constant die temperature during high power operation or high ambient temperature conditions. The float voltage is fixed at 4.2V and the charge current is programmed with an external resistor. The LTC4075 terminates the charge cycle when the charge current drops below the programmed termination threshold after the final float voltage is reached. With power applied to both inputs, the LTC4075/LTC4075X can be put into shutdown mode reducing the DCIN supply current to 20µA, the USBIN supply current to 10µA, and the battery drain current to less than 2µA.

Other features include automatic recharge, undervoltage lockout, charge status outputs, and "power present" status outputs to indicate the presence of wall adapter or USB power.

Trickle Charge

Vin Abs Max

LTC4075

Yes

10V

LTC4075X

No

10V

LTC4075HVX

No

22V

Applications

* Cellular Telephones

* Handheld Computers

* Portable MP3 Players

* Digital Cameras

* Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs

* Automatic Input Power Detection and Selection

* Charge Current Programmable up to 950mA from Wall Adapter Input

* No External MOSFET, Sense Resistor or Blocking Diode Needed

* Thermal Regulation Maximizes Charging Rate Without Risk of Overheating*

* Preset Charge Voltage with ±0.6% Accuracy

* Programmable Charge Current Termination