The NCP1523 step-down PWM DC-DC converter is optimized for portable applications powered from 1-cell Li-ion or 3 cell Alkaline/NiCd/NiMH batteries. The device is available in an adjustable output voltage from 0.9 V to 3.3 V. It uses synchronous rectification to increase efficiency and reduce external part count. The device also has a built-in 3 MHz (nominal) oscillator which reduces component size by allowing use of a small inductor and capacitors. NCP1523 is available in automatic switching PWM/PFM (NCP1523FCT2G) improving system efficiency and in PWM mode only (NCP1523BFCT2G) offering a very efficient load transient solution.