®
RT8859M
Multi-Phase PWM Controller for CPU Core Power Supply
General Description
The RT8859M is a VR12/IMVP7 compliant CPU power
controller which includes two voltage rails : a 4/3/2/1 phase
synchronous buck controller, the CORE VR, and a single
phase buck controller, the AXG VR. The RT8859M adopts
G-NAVP
TM
(Green Native AVP), which is Richtek's
proprietary topology derived from finite DC gain
compensator with current mode control, making it an easy
setting PWM controller, meeting all Intel CPU
requirements of AVP (Active Voltage Positioning). Based
on the G-NAVP
TM
topology, the RT8859M also features a
quick response mechanism for optimized AVP performance
during load transient. The RT8859M supports mode
transition function with various operating states. A serial
VID (SVID) interface is built in the RT8859M to
communicate with Intel VR12/IMVP7 compliant CPU. The
RT8859M 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
RT8859M varies with VID, load and input voltage to further
enhance the efficiency even in CCM. The built-in high
accuracy DAC converts
the SVID code ranging from 0.25V
to 1.52V with 5mV per step. The RT8859M integrates a
high accuracy ADC for platform setting functions, such as
no-load offset or over-current level. The RT8859M provides
VR ready output signals of both CORE VR
and AXG VR.
It also features complete fault protection functions
including over voltage, under voltage, negative voltage, over
current and under voltage lockout. The RT8859M is
available in a WQFN-56L 7x7 small foot print package.
Features
4/3/2/1 + 1 Phase PWM Controller
G-NAVP
TM
Topology
Serial VID Interface
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
Multiple and Single Phase
Fast Transient Response
VR12 / IMVP7 Compatible Power Management
States
VR Ready Indicator
Thermal Throttling
Current Monitor Output
Switching Frequency up to 1MHz per Phase
OVP, UVP, OCP, NVP, UVLO
Slew Rate Setting/Address Flip Function
External No-Load Offset Setting for both Rails
DVID Improvement
Small 56-Lead WQFN Package
RoHS Compliant and Halogen Free
Ordering Information
RT8859M
Package Type
QW : WQFN-56L 7x7 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Note :
Richtek products are :
RoHS compliant and compatible with the current
requirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Applications
VR12 / IMVP7 Intel Core Supply
Notebook/ Desktop Computer/ Servers Multi-phase CPU
Core Supply
AVP Step-Down Converter
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8859M-05 July 2012
www.richtek.com
1
Mobile and portable
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