RT9173B
2A Bus Termination Regulator
General Description
The RT9173B regulator is designed to convert voltage
supplies ranging from 1.7V to 6V into a desired output
voltage of which adjusted by two external voltage divider
resistors. The regulator is capable of sourcing or sinking
up to 2A of current while regulating an output voltage to
within 40mV.
The RT9173B, used in conjunction with series termination
resistors, provides an excellent voltage source for active
termination schemes of high speed transmission lines as
those seen in high speed memory buses and distributed
backplane designs. The voltage output of the regulator can
be used as a termination voltage for DDR SDRAM.
Current limits in both sourcing and sinking mode, plus on-
chip thermal shutdown make the circuit tolerant of the
output fault conditions.
The RT9173B are available in the popular 5-lead TO-252
and fused SOP-8 (the multiple V
CNTL
pins on the SOP-8
package are internally connected but lowest thermal
resistance) surface mount packages.
Features
Support Both DDR I (1.25V
TT
) and DDR II (0.9V
TT
)
Requirements
SOP-8 and TO-252-5 Packages
Capable of Sourcing and Sinking Current
Current-limiting Protection
Thermal Protection
Integrated Power MOSFETs
Generates Termination Voltages for SSTL-2
High Accuracy Output Voltage at Full-Load
Adjustable V
OUT
by External Resistors
Minimum External Components
Shutdown for Standby or Suspend Mode Operation
with High-impedance Output
RoHS Compliant and 100% Lead (Pb)-Free
Applications
DDR Memory Termination Supply
Active Termination Buses
Desktop PC/AGP Graphics
Set Top Box/IPC
Supply Splitter
Ordering Information
RT9173B
Package Type
S : SOP-8
L5 : TO-252-5
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
Pin Configurations
(TOP VIEW)
VIN
GND
REFEN
VOUT
2
3
4
8
7
6
5
VCNTL
VCNTL
VCNTL
VCNTL
Note :
RichTek Pb-free and Green 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.
100%matte tin (Sn) plating.
SOP-8
5
4
3
2
1
VOUT
REFEN
VCNTL (TAB)
GND
VIN
TO-252-5
DS9173B-09 March 2007
www.richtek.com
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