General Description

The RT8871A/B is a 4/3/2-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

RT8871A/B 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 RT8871A/B comes in a small footprint with WQFN48L 7x7 and WQFN-48L 6x6 packages.

Features

z 12V Power Supply Voltage

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

z 3 Embedded MOSFET Drivers (2 for CPU and 1 for

NB)

z Internal Regulated 5V Output

z Support AMD AM2 6-bit Parallel and AM2+ 7-bit

Serial VID with Dual OCP

z Support 3.4MHz High Speed I2

C

z Support Programmable Load Line for CORE and

NB Sections

z Continuous Differential Inductor DCR Current Sense

z Adjustable Frequency (Typically at 300kHz)

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

z Phase-Interleaving for VCORE Controller

z Power Good Indication

z Adjustable Over Current Protection

z Over Voltage Protection

z Small 48-Lead WQFN Package

z RoHS Compliant and Halogen Free

Applications

z Desktop CPU Core Power

z Low Voltage, High Current DC/DC Converter