The RT9248 is a multi-phase buck DC/DC controller
integrated with all control functions for GHz CPU VRM.
The RT9248 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.
RT9248 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 RT9248 supports VRM9 & VRD10 by
VID125 multi-level input, precise initial value & smooth
VCORE transient at VID 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.