The NCP1529MUTBG is a step-down DC-to-DC Converter for portable applications powered from one cell Li-ion or three cell Alkaline/NiCd/NiMH batteries. The device is able to deliver up to 1A on an output voltage range externally adjustable from 0.9 to 3.9V or fixed at 1.2 or 1.35V. It uses synchronous rectification to increase efficiency and reduce external part count. The device also has a built-in 1.7MHz (nominal) oscillator which reduces component size by allowing a small inductor and capacitors. Automatic switching PWM/PFM mode offers improved system efficiency. Additional features include integrated soft-start, cycle-by-cycle current limiting and thermal shutdown protection.