RT8856 Datasheet, PDF (1/23 Pages) Richtek Technology Corporation – Multi-Phase PWM Controller for CPU Core Power Supply

RT8856
Multi-Phase PWM Controller for CPU Core Power Supply
General Description
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 NAVP^TM (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.
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 mode NAVP^TM topology with
high accuracy current sensing amplifier well balances the
RT8856's channel currents.
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.
The RT8856 is available in a WQFN-40L 6x6 small foot
print package.
Applications
z IMVP6.5 Core Supply
z Multi-phase CPU Core Supply
z AVP Step-Down Converter
z Notebook/ Desktop Computer/ Servers
Features
z 1/2 Phase PWM Controller with 2 Integrated
MOSFET Drivers
z IMVP6.5 Compatible Power Management States
(DPSRLVR, PSI, Extended Deeper Sleep Mode)
z NAVP (Native AVP) Topology
z 7-bit DAC
z 0.8% DAC Accuracy
z Fixed V_BOOT (1.1V)
z Differential Remote Voltage Sensing
z Programmable Output Transition Slew Rate Control
z Accurate Current and Thermal Balance
z System Thermal Compensation AVP
z Ringing Free Mode at Light Load Conditions
z Fast Transient Response
z Power Good
z Clock Enable Output
z Thermal Throttling
z Current Monitor Output
z Switching Frequency up to 1MHz Per Phase
z OVP, UVP, NVP, OCP, OTP, UVLO
z 40-Lead WQFN Package
z RoHS Compliant and Halogen Free
Ordering Information
RT8856
Package Type
QW : WQFN-40L 6x6 (W-Type)
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.
Marking Information
RT8856GQW : Product Number
RT8856
GQW
YMDNN
YMDNN : Date Code
DS8856-03 June 2011
www.richtek.com
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