The RT8877D is a 4 + 2 phases PWM controller, and is compliant with AMD SVI2 Voltage Regulator Specification to support both CPU core (VDD) and Northbridge portion of the CPU (VDDNB). The RT8877D features CCRCOT (Constant Current Ripple Constant On-Time) with the G-NAVP (Green-Native AVP), which is Richtek's proprietary topology. The G-NAVP makes it an easy setting controller to meet all AMD AVP (Active Voltage Positioning) VDD/VDDNB requirements. The droop is easily programmed by setting the DC gain of the error amplifier. With proper compensation, the load transient response can achieve optimized AVP performance. The controller also uses the interface to issue VOTF Complete and to send digitally encoded voltage and current values for the VDD and VDDNB domains. It can operate in single phase and diode emulation mode and reach up to 90% efficiency in different modes according to different loading conditions. The RT8877D provides special purpose offset capabilities by pin setting. The RT8877D also provides power good indication, over-current indication (OCP_L) and dual OCP mechanism for AMD SVI2 CPU core and NB. It also features fault protection functions, including over-voltage, under voltage and negative voltage protections.