The BD9S400MUF-CE2, manufactured by ROHM, is a synchronous buck DC/DC converter with 4A MOSFET and a switching voltage regulator. The switching voltage range is from 2.7 to 5.5V. It is designed to supply power to a variety of applications that require small, low voltage output. This small-sized component has features including low ripple noise, low power consumption, and high precision output voltage control. It also has an adjustable soft start, allowing for a gradual start-up, and a fast transient response time. In addition, it is equipped with built-in protection circuits, as well as overcurrent protection and temperature protection.