Multi-Phase PWM Controller for CPU Core Power Supply


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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.

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 NAVPTM 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.


  • IMVP6.5 Core Supply
  • Multi-phase CPU Core Supply
  • AVP Step-Down Converter
  • Notebook/ Desktop Computer/ Servers
  • Notebooks
Key Spec.
Status Active
VID Table Support IMVP6.5
Number of Phases 2
Vcc (typ) (V) 5
Vin (min) (V) 7
Vin (max) (V) 24
Accuracy (Vout>=1V) (+/- %) 0.8
Freq (typ) (kHz) 300
Built-in DAC Generator Yes
Number of MOSFET Drivers 2
Features Adjustable Frequency;Adjustable Soft-Start;DCR Current Sense;Droop Control;Enable Input;OCP;OVP;Power Good;SCP;Voltage Mode Control
Package Type WQFN6x6-40
  • 1/2 Phase PWM Controller with 2 Integrated 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
  • Power Good
  • Clock Enable Output
  • Thermal Throttling
  • Current Monitor Output
  • Switching Frequency up to 1MHz Per Phase
  • 40-Lead WQFN Package
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
Multi-Phase PWM Controller for CPU Core Power Supply2009/12/01
Title Last Update ShareDownload
Multi-Phase PWM Controller for CPU Core Power Supply 2015/05/19
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT8856GQWWQFN6x6-402500 Not available Buy from Distributor