The RT9247 is a multi-phase buck DC/DC controller integrated with all control functions for GHz CPU VRM. The RT9247 controls 2 or 3 buck switching stages operating in interleaved phase set automatically. The multi-phase architecture provides high output current while maintaining low power dissipation on power devices and low stress on input and output capacitors. The high equivalent operating frequency also reduces the component dimension and the output voltage ripple in load transient. RT9247 controls both voltage and current loops to achieve good regulation, response & power stage thermal balance. Precise current loop using RDS(ON) as sense component builds precise load line for strict VRM DC & transient specification and also ensures thermal balance of different power stages. The settings of current sense, droop tuning, VCORE i nitial offset and over current protection are independent to compensation circuit of voltage loop. The feature greatly facilitates the flexibility of CPU power supply design and tuning.