The MAX8621Y/MAX8621Z power-management integrated circuits (PMICs) are designed for a variety of portable devices including cellular handsets. These PMICs include two high-efficiency step-down DC-DC converters, four low-dropout linear regulators (LDOs) with pin-programmable capability, one open-drain driver, a 60ms (typ) reset timer, and power-on/off control logic. These devices offer high efficiency with a no-load supply current of 160A, and their small thin QFN 4mm x 4mm package makes them ideal for portable devices. The step-down DC-DC converters utilize a proprietary 4MHz hysteretic-PWM control scheme that allows for ultra-small external components. Internal synchronous rectification improves efficiency and eliminates the external Schottky diode that is required in conventional step-down converters. The output voltage is adjustable from 0.6V to 3.3V. The output current is guaranteed up to 500mA.