The RT8409 integrates a power MOSFET controller. It is used for step down converters by well controlling the internal MOSFET and regulating a constant output voltage.
The RT8409 features few system component counts and simple system design. Especially, the RT8409 can use a cheap simple drum core inductor in the system instead of an EE core while maintaining the high efficiency.
The RT8409 is housed in a SOP-8 package. The components of the whole system can be made very compact.