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Machine Design

LI-ION Battery Charger IC

The LTC3550-1 is a dual-input Li-Ion battery charger and a high-efficiency synchronous buck regulator, all housed in a low-profile 16-lead 3 X 5-mm DFN package.

The linear charger automatically selects the appropriate power source, a wall adapter or a USB port, to charge single-cell Li-Ion batteries. Stand-alone operation eliminates the need for an external microprocessor for charge termination. It delivers up to 950-mA charge current from a wall adapter supply or up to 500 mA from a USB supply using a constant-I/constant-V algorithm. The final float-voltage accuracy is ±0.6% with either source. A thermal regulation scheme maximizes charging rate without risk of overheating. The unit draws <6 A from the battery in standby and <1 A in shutdown mode. The LTC3550-1's integrated synchronous buck regulator can deliver up to 600-mA continuous output current at efficiencies up to 93%.

Linear Technology Corp., 1630 McCarthy Blvd., Milpitas, CA 95035, (408) 432-1900,

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