DESCRIPTION
The LTC®4066/LTC4066-1 are USB power managers and Li-Ion battery chargers designed to work in portable battery-powered applications. The parts control the total current used by the USB peripheral for operation and battery charging. The total input current can be limited to 100mA, 500mA or “unlimited” (i.e., above 2A). Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the programmed input current limit.
The LTC4066/LTC4066-1 include a standalone constant current/constant-voltage linear charger for single cell Li-ion batteries. The float voltage applied to the battery is held to a tight 0.8% tolerance, and charge current is programmable using an external resistor to ground. A programmable end-of-charge status output (CHRG) indicates full charge. BAT pin charge and discharge currents can be monitored via an analog output (ISTAT). Total charge time is programmable by an external capacitor to ground. When the battery drops 100mV below the float voltage, automatic recharging of the battery occurs. Also featured is an NTC thermistor input used to monitor battery temperature while charging.

FEATURES
■ Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and 5V Wall Adapter
■ Low Loss (50mΩ) Ideal Diode Path from BAT to OUT
■ Programmable Charge Current Detection (CHRG)
■ Load Dependent Charging Guarantees USB Input Current Compliance
■ Analog Gas Gauge Function
■ Charges Single Cell Li-Ion Batteries Directly from USB Port
■ Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate Without Risk of Overheating*
■ Selectable 100% or 20% Current Limit (e.g., 500mA/100mA)
■ Termination Timer Adapts to Actual Charge Current
■ Preset 4.2V Charge Voltage with 0.8% Accuracy (4.1V for LTC4066-1)
■ NTC Thermistor Input for Temperature Qualifi ed Charging
■ Thin Profi le (0.75mm) 24-Lead 4mm × 4mm QFN Package
■ Ultrathin Profi le (0.55mm) 24-Lead 4mm × 4mm UTQFN Package (LTC4066 Only)

APPLICATIONS
■ Portable USB Devices
■ GPS, Cameras, Broadband Wireless Modems
■ Mulitple Input Chargers