General Description

The RT8855 is a 4/3/2/1-phase synchronous buck controller with two integrated MOSFET drivers for CPU power application and a single-phase buck with integrated MOSFET driver for North-Bridge (NB) chipset.The RT8855 uses differential inductor DCR current sense to achieve phase current balance and active voltage positioning. Other features include adjustable operating frequency, power good indication, external error-amp compensation, over voltage protection, over current protection and enable/shutdown for various applications. The RT8855 comes to a small footprint with WQFN-48L 7x7 package.

Features

12V Power Supply Voltage

4/3/2/1-Phase Power Conversion for VCORE Power

3 Embedded MOSFET Drivers (2 for CPU and 1 for NB)

Internal Regulated 5V Output

Support AMD AM2 6-bit Parallel and AM2+ 7-bit Serial VID Tables

Continuous Differential Inductor DCR Current Sense

Adjustable Frequency (Typically at 300kHz)

Selectable 1 or 2 Phase in Power-Saving (PS) Mode

Phase-Interleaving for VCORE and NB Controller

Power Good Indication

Adjustable Over Current Protection

Over Voltage Protection

Small 48-Lead WQFN Package

RoHS Compliant and Halogen Free

Applications

Desktop CPU Core Power

Low Voltage, High Current DC/ DC Converter