Demonstration circuit 1085 is a Linear USB Battery Charger with Dual Buck Regulators featuring the LTC3559. The LTC3559 is a CC/CV 5V/USB linear battery charger with dual high efficiency buck regulators. The part is ideally suited to power single cell 4.2V Li-Ion/Polymer-based handheld applications needing multiple supply rails. The DC1085 has a 4.35V to 5.5V input voltage range and is configured to provide up to 500mA of charge current, though the part is capable of providing up to 950mA. The battery charger has an NTC input for temperature qualified charging. Each monolithic synchronous buck regulator provides up to 400mA of output current while operating at efficiencies greater than 90% over the entire Li-Ion/Polymer range. The buck output voltages are set at 2.5V and 1.2V.