Power manager handles handheld charging

Edited by the Electronicstalk editorial team Apr 21, 2006

An efficient, compact power management chip combines a dual input Li-ion battery charger and a high efficiency synchronous buck regulator in a low-profile 16-lead 3 x 5mm DFN package.

Linear Technology has announced the LTC3550-1, an efficient, compact power management solution for handheld applications containing a dual input Li-ion battery charger and a high efficiency synchronous buck regulator, all housed in a low-profile 16-lead 3 x 5mm DFN package.

The linear battery charger automatically selects the appropriate power source to efficiently charge single-cell Li-ion batteries: a wall adapter or a USB port.

stand-alone operation simplifies design, eliminating the need for an external microprocessor for charge termination.

Using a constant-current/constant-voltage algorithm, the charger can deliver up to 950mA of charge current from a wall adapter supply, or up to 500mA of charge current from a USB supply.

The final float voltage accuracy is +/-0.6% in either case.

The LTC3550-1's battery charger is equipped with a patented thermal regulation scheme which maximises the charging rate without the risk of overheating.

To preserve battery energy, it draws less than 6uA from the battery terminal in standby and less than 1uA in shutdown mode.

The LTC3550-1's integrated synchronous buck regulator can deliver up to 600mA continuous output current.

It uses internal switches with an on-resistance of only 400mohm to deliver efficiencies as high as 93%, maximising battery run time.

In addition, automatic burst mode operation optimises efficiency at light loads, featuring a quiescent current of only 20uA (less than 1uA in shutdown).

Using constant frequency current mode architecture, the buck regulator operates from an input voltage range of 2.5 to 5.5V, making it ideal for single-cell Li-ion or multicell alkaline or NiMH input applications.

The buck regulator has a fixed output voltage of 1.875V, and its high 1.5MHz switching frequency allows the use of tiny low cost capacitors and inductors less than 1mm in height.

Furthermore, the regulator is stable with ceramic capacitors, achieving low output voltage ripple.

The LTC3550-1 is available from stock in a compact 5 x 3 x 0.75mm DFN-16 package.

Pricing starts at $2.00 each for 1000-piece quantities.