The AOZ2231CQI-11 is an I2C controllable, high efficiency, easy-to-use DC-DC synchronous buck regulator capable of operation from a 6.5V to 28V input bus. Ability to control the output voltage using the I2C bus simplifies converter design for microprocessors or SoCs that require dynamic voltage scaling or voltage margining. The device is capable of supplying 4A of continuous output current with an output voltage adjustable from 0.9V to 1.190625V (±2.0%). The AOZ2231CQI-11 integrates an internal linear regulator to generate 5.3V VCC from input. If input voltage is lower than 5.3V, the linear regulator operates at low drop output mode, which allows the VCC voltage is equal to input voltage minus the drop-output voltage of the internal linear regulator. A proprietary constant on-time PWM control with input feed-forward results in ultra-fast transient response while maintaining relatively constant switching frequency over the entire input voltage range. The devices feature multiple protection functions such as VCC under-voltage lockout, cycle-by-cycle current limit, output over-voltage protection, short-circuit protection, and thermal shutdown. The AOZ2231CQI-11 is available in a 4mm×4mm QFN22L package and is rated over a -40°C to +85°C ambient temperature range.