Termination Regulator. RT9173B Datasheet

RT9173B Regulator. Datasheet pdf. Equivalent

RT9173B Datasheet
Recommendation RT9173B Datasheet
Part RT9173B
Description 2A Bus Termination Regulator
Feature RT9173B; RT9173B 2A Bus Termination Regulator General Description The RT9173B regulator is designed to conv.
Manufacture Richtek
Datasheet
Download RT9173B Datasheet




Richtek RT9173B
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 VCNTL pins on the SOP-8
package are internally connected but lowest thermal
resistance) surface mount packages.
Ordering Information
RT9173B
Package Type
S : SOP-8
L5 : TO-252-5
Note :
Lead Plating System
P : Pb Free
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 Support Both DDR I (1.25VTT) and DDR II (0.9VTT)
Requirements
z SOP-8 and TO-252-5 Packages
z Capable of Sourcing and Sinking Current
z Current-limiting Protection
z Thermal Protection
z Integrated Power MOSFETs
z Generates Termination Voltages for SSTL-2
z High Accuracy Output Voltage at Full-Load
z Adjustable VOUT by External Resistors
z Minimum External Components
z Shutdown for Standby or Suspend Mode Operation
with High-impedance Output
z RoHS Compliant and 100% Lead (Pb)-Free
Applications
z DDR Memory Termination Supply
z Active Termination Buses
z Desktop PC/AGP Graphics
z Set Top Box/IPC
z Supply Splitter
Pin Configurations
(TOP VIEW)
VIN
GND
REFEN
VOUT
8
27
36
45
SOP-8
VCNTL
VCNTL
VCNTL
VCNTL
5
4
3
2
1
TO-252-5
VOUT
REFEN
VCNTL (TAB)
GND
VIN
DS9173B-10 April 2011
www.richtek.com
1



Richtek RT9173B
RT9173B
Typical Application Circuit
VCNTL = 3.3V
CCNTL
2N7002
EN
R1 VCNTL
VIN
RT9173B
REFEN
VOUT
R2 GND
VIN = 2.5V
CIN
RTT
COUT RDUMMY
R1 = R2 = 100kΩ, RTT = 50Ω / 33Ω / 25Ω
COUT(MIN) = 10μF (Ceramic) + 1000μF under the worst case testing condition
RDUMMY = 1kΩ as for VOUT discharge when VIN is not present but VCNTL is present
CIN = 470μF (Low ESR), CCNTL = 47μF
Test Circuit
3.3V
2.5V
1.25V
VCNTL
VIN
RT9173B
REFEN
VOUT
GND
VOUT
COUT V
IL
Figure 1. Output Voltage Tolerance, ΔVOUT
1.25V
0.2V
3.3V
A 2.5V
VCNTL
VIN
RT9173B
REFEN
VOUT
GND
VOUT 1.25V
0V
RL COUT V
RL and COUT
Time deleay
Figure 2. Current in Shutdown Mode, ΙSHDN
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2
DS9173B-10 April 2011



Richtek RT9173B
1.25V
3.3V
2.5V
VCNTL
VIN
RT9173B
REFEN
VOUT
GND
VOUT
A
IL
COUT V
Figure 3. Current Limit for High Side, ΙCLHIGH
1.25V
3.3V
Power Supply
with Current Limit
2.5V
VCNTL
VIN
RT9173B
REFEN
VOUT
GND
A
IL
VOUT
COUT V
RT9173B
Figure 4. Current Limit for Low Side, ΙCLLOW
3.3V
2.5V
1.25V
VREFEN 0.2V
1.25V
VOUT
0V
RL and COUT
Time deleay
VCNTL
VIN
RT9173B
REFEN
VOUT
GND
RL
VOUT would be low if VREFEN < 0.2V
VOUT would be high if VREFEN > 0.6V
VOUT
COUT V
Figure 5. REFEN Pin Shutdown Threshold, VTRIGGER
DS9173B-10 April 2011
www.richtek.com
3







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