BD9x Integrated MOSFET DC-DC Buck Converters ROHM Semiconductor BD9x Integrated MOSFET DC-DC Buck Converters are synchronous buck switching regulators with built-in power MOSFETs. These ICs provide currents in a range from 1A to 6A. ROHM BD9x DC-DC Buck Converters deliver fast transient response by employing a constant on-time control system. This allows high oscillating frequency at low inductance. The devices employ an original constant on-time control method that provides low consumption at light load. This feature makes these devices ideal for equipment that demands minimal standby power consumption.