RT9244

Description

The RT9244 is a multi-phase buck DC/DC controller integrated with all control functions for GHz CPU VRM. The RT9244 controls 2, 3 or 4 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.
RT9244 controls both voltage and current loops to achieve good regulation, response & power stage thermal balance. Precise current loop using R_DS(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, V_CORE initial 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.
The DAC output of RT9244 supports K8 CPU by 5-bit VID input, precise initial value & smooth V_CORE transient at VID jump. The IC monitors the V_CORE voltage for PGOOD and over-voltage protection. Soft-start, over-current protection and programmable under-voltage lockout are also provided to assure the safety of microprocessor and power system.