The LTC4050-4.1/LTC4050-4.2 are complete standalone constant-current/constant-voltage linear charge controllers for lithium-ion (Li-Ion) batteries. Charge current is programmable and final float voltage has ±1% accuracy.When the input supply is removed, the LTC4050 automatically enters a low quiescent current sleep mode, dropping the battery drain current to 5µA. An internal comparator detects the near-end-of-charge (C/10) condition while a programmable timer, using an external capacitor, sets the total charge time. Fully discharged cells are automatically trickle charged at 10% of the programmed current until cell voltage exceeds 2.49V. The thermistor interface suspends charging if the cell temperature is outside of a 0°C to 50°C temperature window.The LTC4050 begins a new charge cycle when a discharged battery is connected to the charger or when the input power is applied. In addition, a new charge cycle is automatically started if the battery remains connected to the charger and the cell voltage drops below 3.88V for 4.1V cells or below 3.98V for 4.2V cells.The LTC4050 is available in the 10-pin MSOP package.ApplicationsCellular PhonesHandheld ComputersCharging Docks and Cradles