Richtek RT8884B Manual

Multi-Phase PWM Controller for CPU Core Power Supply
General Description
The RT8884B is a 4/3/2/1 multi-phase synchronous Buck
controller designed to meet Intel VR12.5 compatible CPU
specification with a serial VID control interface. The
RT8884B adopts G-NAVP
Richtek's proprietary topology derived from finite DC gain
of EA amplifier with current mode control, making it easy
to set the droop to meet all Intel CPU requirements of
AVP (Adaptive Voltage Positioning). Based on the G-
TM
NAVP topology, the RT8884B also features a quick
response mechanism for optimized AVP performance
during load transient. The RT8884B supports mode
transition function with various operating states. A Serial
VID (SVID) interface is built in the RT8884B to
communicate with Intel VR12.5 compliant CPU. The
RT8884B supports VID on-the-fly function with three
different slew rates : Fast, Slow and Decay. By utilizing
the G-NAVP TM topology, the operating frequency of the
RT8884B varies with VID, load current and input voltage
to further enhance the efficiency even in CCM. Besides
TM
G-NAVP , the CCRCOT (Constant Current Ripple
Constant On Time) technology provides superior output
voltage ripple over the entire input/output range.
Simplified Application Circuit
©
Copyright 2013 Richtek Technology Corporation. All rights reserved.
DS8884B-01 September 2013
®
TM
(Green Native AVP) which is
RT8884B
VR_RDY
To PCH
VR_HOT
VCLK
To CPU
VDIO
ALERT
Features
Intel VR12.5 Serial VID Interface Compatible
4/3/2/1 Phase PWM Controller
TM
G-NAVP
0.5% DAC Accuracy
Differential Remote Voltage Sensing
Built-in ADC for Platform Programming
Accurate Current Balance
System Thermal Compensated AVP
Diode Emulation Mode at Light Load Condition for
Single Phase Operation
Fast Transient Response
VR Ready Indicator
Thermal Throttling
Current Monitor Output
OVP, UVP, OCP, NVP, UVLO
External No-Load Offset Setting
DVID Enhancement
Small 32-Lead WQFN Package
RoHS Compliant and Halogen Free
Applications
VR12.5 Intel Core Power Supply
Notebook/Desktop Computer/Servers Multi-phase CPU
Core Power Supply
AVP Step-Down Converter
RT9624A
PWM1
RT9624A
PWM2
PWM3 RT9624A
PWM4
RT9624A
is a registered trademark of Richtek Technology Corporation.
RT8884B
Topology
V
CORE
www.richtek.com
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