The MAX1759 is a buck/boost regulating charge pump that generates a regulated output voltage from a single lithium-ion (Li+) cell, or two or three NiMH or alkaline cells for small hand-held portable equipment. The MAX1759 operates over a wide +1.6V to +5.5V input voltage range and generates a fixed 3.3V or adjustable (2.5V to 5.5V) output (Dual ModeTM). Maxim's unique charge-pump architecture allows the input voltage to be higher or lower than the regulated output voltage. Despite its high 1.5MHz operating frequency, the MAX1759 maintains low 50A quiescent supply current. Designed to be an extremely compact buck/boost converter, this device requires only three small ceramic capacitors to build a complete DC-DC converter capable of generating a guaranteed 100mA (min) output current from a +2.5V input. For added flexibility, the MAX1759 also includes an open-drain power-OK (POK) output that signals when the output voltage is in regulation.