RT8855 Datasheet, PDF (1/18 Pages) Richtek Technology Corporation – 4/3/2/1-Phase PWM Controller for AMD AM2/AM2+ CPUs

RT8855
4/3/2/1-Phase PWM Controller for AMD AM2/AM2+ CPUs
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.
Applications
z Desktop CPU Core Power
z Low Voltage, High Current DC/ DC Converter
Ordering Information
RT8855
Package Type
QW : WQFN-48L 7x7 (W-Type)
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Features
z 12V Power Supply Voltage
z 4/3/2/1-Phase Power Conversion for V_CORE 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 Tables
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 V_CORE and NB 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
Pin Configurations
(TOP VIEW)
48 47 46 45 44 43 42 41 40 39 38 37
PWROK 1
RT 2
FBRTN 3
FBRTN_NB 4
FB_NB 5
COMP_NB 6
ISP_NB 7
ISN_NB 8
ADJ 9
OFS 10
COMP 11
FB 12
GND
36 BOOT_NB
35 BOOT1
34 UGATE1
33 PHASE1
32 LGATE1
31 VCC12
30 LGATE2
29 PHASE2
28 UGATE2
49
27 BOOT2
26 PWM3
25 PWM4
13 14 15 16 17 18 19 20 21 22 23 24
WQFN-48L 7x7
DS8855-01 April 2011
www.richtek.com
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