The LTC3552-1 is a complete constant-current/constant-voltage linear charger and dual fixed output DC/DC converter for single cell lithium-ion batteries. Its DFN package and low external component count make the LTC3552-1 ideally suited for portable applications. Furthermore, the LTC3552-1 is designed to work within USB power specifications.No external sense resistor or external blocking diode are required due to the internal MOSFET architecture. The charge voltage is fixed at 4.2V and the charge current is programmed with a resistor. The charge cycle terminates when the charge current drops below the programmed termination threshold after the final float voltage is reached. When the input supply (wall adapter or USB supply) is removed, the LTC3552-1 enters a low current state dropping the battery drain current to less than 2μA. Thermal regulation maximizes charge rate without risk of overheating.The synchronous step-down switching regulators generate fixed output voltages of 1.8V and 1.575V. The switching frequency is set at 2.25MHz, allowing the use of small surface mount inductors and capacitors.VOUTLTC3552Adjustable (0.6V to 5V)LTC3552-11.8V & 1.575VApplicationsCellular Telephones, PDAs, MP3 PlayersBluetooth Applications