LTC4069-4.4 - Standalone 750mA Li-Ion Battery Charger in 2 × 2 DFN with NTC Thermistor Input

The LTC4069-4.4 is a complete constant-current/constant- voltage linear charger for high capacity single-cell lithium-ion batteries with a 4.4V float voltage. The 2mm × 2mm DFN package and low external component count make the LTC4069-4.4 especially well-suited for portable applications. Furthermore, LTC4069-4.4 is specifically designed to work within USB power specifications.

The CHRG pin indicates when charge current has dropped to ten percent of its programmed value (C/10). An internal timer terminates charging according to battery manufacturer specifications.

No external sense resistor or blocking diode is required due to the internal MOSFET architecture. Thermal feedback regulates charge current to limit the die temperature during high power operation or high ambient temperature conditions.

When the input supply (wall adapter or USB supply) is removed, the LTC4069-4.4 automatically enters a low current state, dropping battery drain current to less than 1µA. With power applied, LTC4069-4.4 can be put into shutdown mode, reducing the supply current to less than 20µA.

The LTC4069-4.4 also includes automatic recharge, lowbattery charge conditioning (trickle charging), soft-start (to limit inrush current) and an NTC thermistor input used to monitor battery temperature.

The LTC4069-4.4 is available in a tiny 6-lead, low profile (0.75mm) 2mm × 2mm DFN package.

Features

Complete Linear Charger in 2mm × 2mm DFN Package
C/10 Charge Current Detection Output
Timer Charge Termination
Charge Current Programmable Up to 750mA with 5% Accuracy
No External MOSFET, Sense Resistor or Blocking Diode Required
NTC Thermistor Input for Temperature Qualified Charging
Preset 4.4V Float Voltage with 0.6% Accuracy
Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charge Rate Without Risk of Overheating
Charge Current Monitor Output for Gas Gauging
Automatic Recharge
Charges Single-Cell Li-Ion Batteries Directly from USB Port
20µA Supply Current in Shutdown Mode
Soft-Start Limits Inrush Current
Tiny 6-Lead (2mm × 2mm) DFN Package