3.3V fixed output non-isolated DC buck voltage regulator, ultra small module 22x17x4mm Great for micro-controllers like the ESP8266, devices designed for 2x AA batteries, and more. Input: 4.5-28V, Output:3.3V, 3A Peak / 1.5A Sustained Efficiency: Up to 92% (depends on the difference between input and output voltage) This module uses synchronous rectification, the most efficient power conversion available. 1.0MHz Switching Frequency,