General Description

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.

Features

 4/3/2/1-Phase (VDD) + 2/1/0-Phase (VDDNB) PWM

Controller

 G-NAVPTM Topology

 Support Dynamic Load-Line and Zero Load-Line

 Diode Emulation Mode at Light Load Condition

 SVI2 Interface to Comply AMD Power Management

Protocol

 Build-in ADC for VOUT and IOUT Reporting

 Immediate OV, UV and NV Protections and UVLO

 Programmable Dual OCP Mechanism

 0.5% DAC Accuracy

 Fast Transient Response

 Power Good Indicator

 Over-Current Indicator

 52-Lead WQFN Package

 RoHS Compliant and Halogen Free

Applications

 AMD SVI2 CPU

 Desktop Computer