The high efficiency step-down regulators are fully integrated and switch at a high 1.5 MHz fixed frequency. They automatically transition to variable frequency operation at light loads for improved efficiency. DC-DC1 (Buck1) is designed for high output current and low dropout voltage (200mV at 1.2A). DC-DC2 (Buck2) is a 600mA regulator with a two step dynamic output voltage capability. One option allows the output voltage of DC-DC2 (Buck2) to be set to either 1.0V or 1.3V with the SELB2 logic pin.