Linear Technology Corporation announces the LTC3552-1, an efficient, compact power management solution for handheld applications. The LTC3552-1 includes a standalone Li-Ion battery charger and a high efficiency dual synchronous buck regulator housed in a low-profile 3mm x 5mm DFN package. The linear battery charger can deliver up to 950mA charge current from a wall adapter supply, or up to 500mA charge current from a USB supply. Standalone operation simplifies design, eliminating the need for an external microprocessor for charge termination. The final float voltage accuracy is ±1%. The LTC3552-1's battery charger is equipped with a patented thermal regulation scheme which maximizes the charging rate without the risk of overheating. To preserve battery energy, it draws < 2.5μA from the battery terminal in standby and < 1μA in shutdown mode.
The LTC3552-1's two integrated synchronous buck regulators deliver up to 800mA continuous output current at 1.8V, and up to 400mA at 1.575V, respectively. The internal switches feature an RDS(ON)range of 0.3Ω to 0.35Ω to deliver efficiencies as high as 92%, maximizing battery run time. In addition, automatic Burst Mode operation optimizes efficiency at light loads with quiescent current of only 40μA (< 1μA in shutdown). Using a constant frequency current mode architecture, the buck regulator operates from an input voltage range of 2.5V to 5.5V, making it ideal for single-cell Li-Ion/Li-Polymer, multi-cell alkaline or NiMH input applications. Its high 2.25MHz switching frequency allows the utilization of tiny low cost capacitors and inductors less than 1mm in height. Furthermore, the regulator is stable with ceramic capacitors, achieving very low output voltage ripple.
The LTC3552-1 is available from stock in a compact 3mm x 5mm x 0.75mm DFN-16 package. Pricing starts at $2.30 each for 1,000-piece quantities.
Summary of Features
Complete Linear Charger and Dual DC/DC Regulator
Charge Current Programmable up to 950mA from Wall Adapter Input
High Efficiency Dual Synchronous DC/DC Buck Converters
Buck Converter Outputs: 1.8V @800mA and 1.575V @400mA
No External MOSFET, Sense Resistor or Blocking Diodes Needed
Thermal Regulation Maximizes Charging Rate without Overheating
Charges Directly from a USB Port
Preset Charge Voltage with ±1% Accuracy
Standalone Operation: Programmable Charge Current Termination
2.25MHz Constant Frequency Operation (Buck Converter)
Charge Status Output
Thermally-Enhanced, Low Profile (0.75mm) 16-Lead 3mm x 5mm DFN package