®
RT8856
Multi-Phase PWM Controller for CPU Core Power Supply
General Description
Features
1/2 Phase PWM Controller with 2 Integrated
The RT8856 is a single/dual phase PWM controller with
two integrated MOSFET drivers. Moreover, it is compliant
with Intel IMVP6.5 Voltage Regulator Specification to fulfill
its mobile CPU Vcore power supply requirements. The
RT8856 adopts NAVPTM (Native AVP) which is Richtek's
proprietary topology derived from finite DC gain
compensator peak current mode, making it an easy setting
PWM controller that meets all Intel AVP (Active Voltage
Positioning) mobile CPU requirements.
MOSFET Drivers
IMVP6.5 Compatible Power Management States
(DPSRLVR, PSI, Extended Deeper Sleep Mode)
NAVP (Native AVP) Topology
7-bit DAC
0.8% DAC Accuracy
Fixed VBOOT (1.1V)
Differential Remote Voltage Sensing
Programmable Output Transition Slew Rate Control
Accurate Current and Thermal Balance
System Thermal Compensation AVP
Ringing Free Mode at Light Load Conditions
Fast Transient Response
The output voltage of the RT8856 is set by 7-bit VID code.
The built-in high accuracy DAC converts the VID code
ranging from 0V to 1.5V with 12.5mV per step. The system
accuracy of the controller can reach 1.5%. The part
supports VID on-the-fly and mode change on-the-fly
functions that are fully compliant with IMVP6.5
specification. It operates in single phase, dual phase and
RFM. It can reach up to 90% efficiency in different modes
according to different loading conditions. The droop load
line can be easily programmed by setting the DC gain of
the error amplifier. With proper compensation, the load
transient can achieve optimized AVP performance. This
chip controls soft-start and output transition slew rate via
a capacitor. It supports both DCR and sense resistor
current sensing. The current modeNAVPTM topology with
high accuracy current sensing amplifier well balances the
RT8856's channel currents.
Power Good
Clock Enable Output
Thermal Throttling
Current Monitor Output
Switching Frequency up to 1MHz Per Phase
OVP, UVP, NVP, OCP, OTP, UVLO
40-Lead WQFN Package
RoHS Compliant and Halogen Free
Ordering Information
RT8856
Package Type
QW : WQFN-40L 6X6 (W-Type)
(Exposed Pad-Option 1)
The RT8856 provides power good, clock enabling and
thermal throttling output signals for IMVP6.5 specification.
It also features complete fault protection functions
including over voltage, under voltage, negative voltage, over
current, thermal shutdown, and under voltage lockout.
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
The RT8856 is available in a WQFN-40L 6x6 small foot
print package.
Applications
IMVP6.5 Core Supply
Multi-phase CPU Core Supply
AVP Step-Down Converter
Notebook/Desktop Computer/ Servers
Copyright 2015 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS8856-05 July 2015
www.richtek.com
1