RT8857 Datasheet, PDF (1/26 Pages) Richtek Technology Corporation – 4/3/2/1-Phase PWM Controller with Embedded Drivers for CPU Core Power Supply

RT8857/A
4/3/2/1-Phase PWM Controller with Embedded Drivers
for CPU Core Power Supply
General Description
The RT8857/A is a 4/3/2/1-phase synchronous buck
controller with 2 integrated MOSFET drivers for Intel
VR11.1/VR10.x and AMD K8/K8_M2 CPUs power
application. RT8857/A uses differential inductor DCR
current sense to achieve phase current balance and active
voltage positioning. Other features include adjustable
operating frequency, adjustable soft start, power good
indication, external error-amp compensation, over voltage
protection, over current protection, VRHOT sensing and
IMON for various applications. RT8857/A comes to a small
footprint with WQFN-48L 7x7 package
Ordering Information
RT8857/A
Package Type
QW : WQFN-48L 7x7 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Support V_IN : 5/12V
Support V_IN : 12V
z VIN is the input voltage of MOSFET power stage.
z 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.
Applications
z Desktop CPU Core Power
z Low Voltage, High Current DC/ DC Converter
Features
z 12V Power Supply Voltage
z 4/3/2/1-Phase Power Conversion
z 2 Embedded MOSFET Drivers
z Internal Regulated 5V Output
z VID table for INTEL VR11.1/VR10.x and AMD K8/
K8_M2 CPUs
z Continuous Differential Inductor DCR Current Sense
z Adjustable Soft Start
z Adjustable Frequency
z Power Good Indication
z Adjustable Over Current Protection
z Over Voltage Protection
z VRHOT Sensing with External Thermistor
z IMON Output Current Indication
z Power State Indicator (PSI)
z Support MOSFET Power Stage Input Voltage (V_IN)
Down to 5V (RT8857A Only)
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
FBRTN 1
QR1 2
QR2 3
SS/EN 4
COMP 5
FB 6
OFS 7
RT 8
ADJ 9
IMAX 10
IMAXPSI 11
IMONFB 12
GND
36 PWRGD
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
DS8857/A-01 April 2011
www.richtek.com
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