The ADP3020 is a highly efficient dual synchrounous buck switching regulator controller optimized for converting the battery or adapter input into the system supply voltages required in notebook computers. The ADP3020 uses a dual-mode PWM/Power Saving Mode architecture to maintian efficiency over a wide load range. The oscillator frequency can be pro-grammed for 200 kHz, 300 kHz, or 400 kHz operation, or it can be synchronized to an external clock signal of up to 600 kHz. The ADP3020 provides accurate and reliable short circuit pro-tection using an internal current sense circuit, which reduces cost and increases overall efficiency. Other protection features include programmable soft-start, UVLO, and integrated output undervoltage/overvoltage protection. The ADP3020 contains a linear regulator controller that is designed to drive an external P-channel MOSFET or PNP transistor. The linear regulator output is adjustable, and can be used to generate the auxiliary voltages required in many laptop designs.