RT9243 pdf ,RT9243 datasheet (

The RT9243 is a multi-phase buck DC/DC controller
integrated with all control functions for GHz CPU VRM.
The RT9243 controls 2, 3 or 4 buck switching stages
operating in interleaved phase set automatically. The multiphase
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.
RT9243 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 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 RT9243 supports VRD10.x by 6-bit
VID input, precise initial value & smooth VCORE transient
at VIID jump. The IC monitors the VCORE 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.