RT8855应用电路及参数

4/3/2/1-Phase PWM Controller for AMD AM2/AM2+ CPUs

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 

Application

• Desktop CPU Core Power
• Low Voltage, High Current DC/ DC Converter

Typical Applications Circuit