RT9172
3A Fixed Output Voltage LDO Regulator
General Description
The RT9172 series of low-dropout linear regulators operate
from a +2.25V to +6.0V input supply. A wide range of preset
output voltage options is available. These low dropout linear
regulators respond very fast to step changes in load, which
are suitable for low voltage microprocessor applications.
The RT9172 uses an internal PMOS as the pass device,
which does not cause extra GND current in heavy load
and dropout condition. The shutdown mode of low operation
current makes the IC suitable for power-saving systems.
The other features include current limiting and over
temperature protection.
Features
Low Dropout Voltage
Low Ground Pin Current
Load Regulation of 0.4% at 3A
0.5mA Quiescent Current in Shutdown Mode
Guaranteed Output Current of 3A DC
Available in TO-263 and TO-220 Packages
Output Voltage Accuracy
±
1.5%
Error Flag Indicates Output Status
Sense Option Improves Better Load Regulation
Extremely Low Output Capacitor Requirements
Over-Temperature/Over- Current Protection
RoHS Compliant and 100% Lead (Pb)-Free
Ordering Information
RT9172
-
Applications
Microprocessor Power Supplies
GTL, GTL+, BTL, and SSTL Bus Terminators
Power Supplies for DSPs
SCSI Terminator
Post Regulators
High Efficiency Linear Regulators
Battery Chargers
Other Battery Powered Applications
Package Type
T5 : TO-220-5
M5 : TO-263-5
T : TO-220
M : TO-263
G : SOT-223
S : SOP-8
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
Output Voltage
15 : 1.5V
16 : 1.6V
:
32 : 3.2V
33 : 3.3V
S : Pin Out Exchange
N : Pin 5 bond SENSE
F : Pin 5 bond FLG
Pin Configurations
(TOP VIEW)
VIN GND VOUT
(TAB)
2
3
1
2
3
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.
1
2
TO-220
1
VIN GND VOUT
(TAB)
TO-263
3
VOUT
SENSE
GND
NC
2
3
4
8
7
6
5
VIN
GND
GND
EN
VIN GND VOUT
(TAB)
SOP-8
SOT-223
DS9172-14 March 2007
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1
RT9172
5
4
3
2
1
SENSE/FLG
VOUT
GND (TAB)
VIN
EN
5
4
3
2
1
SENSE/FLG
VOUT
GND (TAB)
VIN
EN
TO-220-5
RT9172N-
CT5
RT9172F-
CT5
TO-263-5
RT9172N-
CM5
RT9172F-
CM5
5
4
3
2
1
VOUT
SENSE
GND (TAB)
EN
VIN
5
4
3
2
1
VOUT
SENSE
GND (TAB)
EN
VIN
TO-220-5
RT9172S-
CT5
TO-263-5
RT9172S-
CM5
Functional Pin Description
Pin No.
RT9172-
RT9172F
RT9172N
RT9172S
RT9172-
RT9172-
1
2
3
4
5
--
1
2
3
4
--
5
2
1
3
5
--
4
--
1
2
3
--
--
CT
CM
CG
EN
VIN
GND
VOUT
FLG
SENSE
Chip Enable (Active Hight)
Power Input Voltage
Ground
Output Voltage
ERROR Flag
Remote Sense
Pin Name
Pin Function
Typical Application Circuit
RT9172-25
V
IN
= 3.3V
C
IN
10uF
VIN
VOUT
GND
V
OUT
2.5V, 3A
+
+
C
OUT
Figure 1
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2
DS9172-14 March 2007
RT9172
RT9172N-25
V
IN
= 3.3V
C
IN
10uF
VIN
10K
EN
SENSE
GND
VOUT
I
LOAD
L
O
A
D
+
+
Trace resistance = R
t
V
LOAD
= 2.5V
C
OUT
Figure 2
RT9172F-25
V
IN
= 3.3V
C
IN
10uF
VIN
10K
EN
GND
FLG
VOUT
+
Trace resistance = R
t
V
OUT
= 2.5V
V
LOAD
= 2.5V -I
LOAD
R
t
I
LOAD
L
O
A
D
+
10K
C
OUT
Figure 3
Recommend C
OUT
: Please note that the part must be paralleled with the least a 100μF electrolytic capacitor when
using a 10μF (or greater) ceramic type as the output capacitor to prevent the output oscillating.
Function Block Diagram
RT9172F
VIN
VOUT
Buffer
Amlifier
Thermal
Current
Limiting
Sensor
-
V
REF
GND
EN
+
-
+
FLG
DS9172-14 March 2007
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3
RT9172
RT9172N/RT9172S
VIN
VOUT
Buffer
Amlifier
Thermal
SENSE
Current
Limiting
Sensor
-
V
REF
-
EN
+
GND
RT9172
VIN
VOUT
Buffer
Amlifier
Thermal
Current
Limiting
Sensor
V
REF
+
GND
Absolute Maximum Ratings
Input Voltage ------------------------------------------------------------------------------------------------------------ 6V
Power Dissipation, P
D
@ T
A
= 25°C
SOT-223 ----------------------------------------------------------------------------------------------------------------- 0.741W
SOP-8 -------------------------------------------------------------------------------------------------------------------- 0.625W
TO-263 ------------------------------------------------------------------------------------------------------------------- 2.222W
TO-220 ------------------------------------------------------------------------------------------------------------------- 1.820W
Package Thermal Resistance (Note 4)
SOT-223,
θ
JC
----------------------------------------------------------------------------------------------------------- 23°C/W
SOT-223,
θ
JA
------------------------------------------------------------------------------------------------------------ 135°C/W
SOP-8,
θ
JC
-------------------------------------------------------------------------------------------------------------- 45°C/W
SOP-8,
θ
JA
-------------------------------------------------------------------------------------------------------------- 160°C/W
TO-263,
θ
JC
------------------------------------------------------------------------------------------------------------- 7.8°C/W
TO-263,
θ
JA
------------------------------------------------------------------------------------------------------------- 45°C/W
TO-220,
θ
JC
------------------------------------------------------------------------------------------------------------- 15°C/W
TO-220,
θ
JA
------------------------------------------------------------------------------------------------------------- 55°C/W
ESD Rating ------------------------------------------------------------------------------------------------------------- 3 kV
Storage Temperature Range ----------------------------------------------------------------------------------------
−
65°C to 150°C
Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260°C
Junction Temperature Range ----------------------------------------------------------------------------------------
−
40°C to +125°C
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DS9172-14 March 2007
RT9172
Electrical Characteristics
(Limits in standard typeface are for T
A
= 25°C, unless otherwise specified: V
IN
= V
O(NOM)
+ 1.0V, I
L
= 10mA,
C
OUT
= 10μF(Electrolytic), V
EN
= V
IN
)
Parameter
Output Voltage Tolerance
Input Voltage Range
Line Regulation
Load Regulation
Symbol
Test Conditions
Min
-1.5
Typ
0
--
0.35
0.4
0.1
0.1
400
1.2
0.5
5
5
170
10
V
IN
0
0.1
1
--
Max
+1.5
5.5
1
1
0.4
0.4
700
3
5
--
--
--
--
--
0.4
--
--
--
Units
%
V
%
%
V
IN
ΔV
LINE
ΔV
LOAD
V
DROP
I
Q
I
GSD
I
O(PEAK)
I
LIMIT
T
SD
Guaranteed by design
Guaranteed by design
Output = High
Output = Low
V
EN
= V
IN
I
LEAKAGE
V
FLG
= 0.5V
V
EN
= 0V
V
OUT
+ 0.4V
<
V
IN
<
5.5V
Note 1
Note 2
Note 3
2.25
--
--
--
--
--
--
--
3.5
3.5
--
--
1.2
--
--
--
2
Dropout Voltage
Quiescent Current
Shutdown Supply Current
Peak Output Current
Short Circuit Protection
Current Limit
Over Temperature Protection
Shutdown Threshold
Thermal Shutdown Hysteresis
Shutdown Function
EN Pin Shutdown Threshold
EN Input Current
FLG Pin Leakage Current
FLG Pin Sink Current
I
L
= 3A
mV
mA
μA
A
A
°C
°C
V
EN
V
nA
nA
mA
Note 1.
RT9172-CX, RT9172F-XXCX5, 10mA < I
L
< 3A
Note 2.
RT9172S-XXCX5, RT9172N-XXCX5, 10mA < I
L
< 3A
Note 3.
RT9172CS, 10mA < I
L
< 1.5A
Note 4.
θ
JA
is measured in the natural convection at T
A
= 25°C on a low effective thermal conductivity test board of
JEDEC 51-3 thermal measurement standard. The case point of
θ
JC
is on the center of the exposed pad. The pad size
is 125mm
2
on TO-263 packages.
DS9172-14 March 2007
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