RT9179
Adjustable, 300mA LDO Regulator with Enable
General Description
The RT9179 is a high performance linear voltage regulator
with enable high function and adjustable output with a
1.175V reference voltage. It operates from an input of 3V
to 5.5V and provides output current up to 300mA with two
external resistors to set the output voltage ranges from
1.175V to 4.5V.
The RT9179 has superior regulation over variations in line
and load. Also it provides fast respond to step changes in
load. Other features include over-current and over-
temperature protection. The device has enable pin to reduce
power consumption in shutdown mode.
The devices is available in the popular
SOT-23-5
package.
Features
300mV Dropout @ 300mA
150uA Low Ground Pin Current
Excellent Line and Load Regulation
<1uA Standby Current in Shutdown Mode
Guaranteed 300mA Output Current
Stable with 1uF Input and Output Ceramic Capacitor
Adjustable Output Voltage Ranges from 1.175V to
4.5V
Over-Temperature/Over-Current Protection
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Battery-Powered Equipment
Graphic Card
Peripheral Cards
PCMCIA Card
Ordering Information
RT9179
Package Type
B : SOT-23-5
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Note :
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.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Pin Configurations
(TOP VIEW)
VOUT
5
2
ADJ
4
3
VIN GND EN
SOT-23-5
DS9179-11 April 2011
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1
RT9179
Typical Application Circuit
RT9179
V
IN
Chip Enable
C
3
0.1uF
C
1
1uF
EN
GND
ADJ
R
2
VIN
VOUT
R
1
C
2
1uF
V
OUT
V
OUT
= 1.175 x (
1
+
R
1
) Volts
R
2
Adjustable Operation
Note: The external feedback resistors are in hundreds of OHM to hundreds of kOHM ranges.
Functional Pin Description
Pin No. Pin Name
1
2
3
VIN
GND
EN
Power Input Voltage
Ground
Chip Enable (Active High)
Adjust Output Voltage. The output voltage is set by the internal feedback resistors when
4
5
ADJ
VOUT
this pin grounded. If external feedback resistors are applied, the output voltage will be:
V
OUT
= 1.175
×
(1 +
Output Voltage
R
1
) Volts
R
2
Pin Function
Function Block Diagram
Current-Limit
and
Thermal Protection
Thermal
SHDN
+
_
Error
Amplifier
MOS
Driver
VOUT
ADJ
GND
EN
Shutdown
and
Logic Control
VIN
1.175V
V
REF
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2
DS9179-11 April 2011
RT9179
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 6V
Power Dissipation, P
D
@ T
A
= 25°C
SOT-23-5 ---------------------------------------------------------------------------------------------------------------
0.4W
Package Thermal Resistance (Note 2)
SOT-23-5,
θ
JA
--------------------------------------------------------------------------------------------------------- 250°C/W
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C
Junction Temperature ----------------------------------------------------------------------------------------------- 150°C
Storage Temperature Range ---------------------------------------------------------------------------------------
−
65°C to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V
Recommended Operating Conditions
(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------ 3V to 5.5V
Enable Input Voltage ------------------------------------------------------------------------------------------------ 0V to 5.5V
Junction Temperature Range --------------------------------------------------------------------------------------
−
40°Cto 125°C
Electrical Characteristics
(V
IN
= V
OUT
+ 0.7V, I
OUT
= 10uA, C
IN
= C
OUT
= 1uF (Ceramic), T
A
= 25° C unless otherwise specified)
Parameter
Reference Voltage Tolerance
Adjust Pin Current
Output Voltage Range
Quiescent Current
Standby Current
Current Limit
Dropout Voltage
Line Regulation
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
EN Threshold
EN Current
Logic-Low Voltage
Logic-High Voltage
(Note 7)
(Note 5)
(Note 6)
Symbol
V
REF
I
ADJ
V
OUT
I
Q
I
STBY
I
LIM
V
DROP
ΔV
LINE
T
SD
ΔT
SD
V
IL
V
IH
I
EN
Test Conditions
Min
1.163
--
1.175
Typ
1.175
--
--
150
--
--
10
300
0.001
170
40
--
--
--
Max
1.187
10
4.5
--
1
--
--
-
--
--
--
0.4
--
10
Unit
V
nA
V
μA
μA
A
mV
%/V
°C
°C
V
nA
Enabled, I
OUT
= 0mA
V
IN
= 5.5V, Shutdown
I
OUT
= 10mA
I
OUT
= 300mA
V
OUT
+ 0.7V
<
V
IN
<
5.5V
--
--
0.5
--
--
--
--
--
V
IN
= 3.3V, Shutdown
V
IN
= 3.3V, Enable
V
IN
= 5.5V, Enable
--
2.0
--
DS9179-11 April 2011
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3
RT9179
Note 1.
Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the
operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended
periods may remain possibility to affect device reliability.
Note 2.
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.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Note 5.
Quiescent, or ground current, is the difference between input and output currents. It is defined by I
Q
= I
IN
- I
OUT
under
no load condition (I
OUT
= 0mA). The total current drawn from the supply is the sum of the load current plus the ground
pin current.
Note 6.
Standby current is the input current drawn by a regulator when the output voltage is disabled by a shutdown signal
(V
EN
≤
0.4V). It is measured with V
IN
= 5.5V.
Note 7.
The dropout voltage is defined as V
IN
-V
OUT
, which is measured when V
OUT
is V
OUT(NORMAL)
−
100mV.
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DS9179-11 April 2011
RT9179
Typical Operating Characteristics
Output Voltage vs. Temperature
3.29
ADJ Pin Voltage vs. Temperature
1.2
ADJ Pin Voltage (V)
3.28
V
IN
= 5V
R1 = 1.8KΩ
R2 = 1kΩ
V
IN
= 5V
1.19
1.18
1.17
1.16
1.15
1.14
Output Voltage (V)
3.27
3.26
3.25
3.24
-50
-25
0
25
50
75
100
125
-50
-25
0
25
50
75
100
125
Temperature
(
°
C)
Temperature
(
°
C)
Quiescent Current vs. Temperature
160
Quiescent Current vs. Input Voltage
150
V
IN
= 5V
150
Quiescent Current (uA)1
Quiescent Current (uA)
140
140
130
130
120
-50
-25
0
25
50
75
100
125
120
3
3.5
4
4.5
5
5.5
Temperature
(
°
C)
Input Voltage (V)
-20
-30
PSRR
Dropout Voltage vs. Io
400
350
V
OUT
= 3.3V
T
J
= 125°C
T
J
= 25°C
-50
-60
-70
-80
-90
Dropout Voltage (mV)
-40
300
250
200
150
100
50
0
PSRR (dB)
T
J
= -40°C
V
IN
= 4V
I
L
= 10mA
C
OUT
= 1uF (X7R)
10
100
-100
1K
1000
10K
10000
100K
100000
0
50
100
150
200
250
300
Frequency (Hz)
DS9179-11 April 2011
Io (mA)
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