RT9178
200mA, Ultra-Low Noise, Ultra-Fast CMOS LDO Regulator
General Description
The RT9178 is designed for portable RF and wireless
applications with demanding performance and space
requirements.
The RT9178’ s performance is optimized for battery-
powered systems to deliver ultra low noise and low
quiescent current. A noise bypass pin is also available for
further reduction of output noise. Regulator ground current
increases only slightly in dropout, further prolonging the
battery life. The RT9178 also works with low-ESR ceramic
capacitors, reducing the amount of board space necessary
for power applications, critical in hand-held wireless
devices.
The RT9178 consumes less than 0.01uA in shutdown mode
and has fast turn-on time less than 100us. The other
features include ultra low dropout voltage, high output
accuracy, current limiting protection, and high ripple
rejection ratio. Available in the SOT-23-5 package.
Features
Ultra-Low-Noise for RF Application
Ultra-Fast Response in Line/Load Transient
Quick Start-Up (Typically 100us)
< 0.01uA Quiescent Current When Shutdown
Low Dropout : 200mV at 200mA
Wide Operating Voltage Ranges : 2.5V to 6V
TTL-Logic-Controlled Shutdown Input
Low Temperature Coefficient
Current Limiting Protection
Thermal Shutdown Protection
Only 1uF Output Capacitor Required for Stability
High Power Supply Rejection Ratio
Custom Voltage Available
RoHS Compliant and 100% Lead (Pb)-Free
Applications
CDMA/GSM Cellular Handsets
Battery-Powered Equipment
Laptop, Palmtops, Notebook Computers
Hand-Held Instruments
PCMCIA Cards
Portable Information Appliances
Ordering Information
RT9178-
Package Type
B : SOT-23-5
BR : SOT-23-5 (R-Type)
Marking Information
Note :
For marking information, contact our sales representative
Lead Plating System
P : Pb Free
directly or through a Richtek distributor located in your
G : Green (Halogen Free and Pb Free)
area.
Output Voltage
24 : 2.4V
Pin Configurations
25 : 2.5V
:
(TOP VIEW)
31 : 3.1V
32 : 3.2V
BP
EN
VOUT
BP
2H : 2.85V
5
2
4
3
5
2
4
3
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.
VIN GND EN
VOUT GND VIN
SOT-23-5
R-Type
SOT-23-5
DS9178-18 April 2011
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1
RT9178
Typical Application Circuit
RT9178
V
IN
C
IN
1uF
VIN
GND
EN
BP
VOUT
C
OUT
2.2uF
V
OUT
+
+
Chip Enable
C
BP
10nF
Functional Pin Description
Pin No.
SOT-23-5
1
5
2
3
4
SOT-23-5 (R-Type)
3
1
2
4
5
VIN
VOUT
GND
EN
BP
Power Input Voltage
Output Voltage
Ground
Enable Input Logic, Active Low. If the Shutdown Feature is not
Required, Connect EN to VIN.
Reference Noise Bypass
Pin Name
Pin Function
Function Block Diagram
EN
Quick
Start
BP
V
REF
+
-
Error
Amplifier
Shutdown
and
Logic Control
VIN
MOS Driver
VOUT
Current-Limit
and
Thermal
Protection
GND
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2
DS9178-18 April 2011
RT9178
Absolute Maximum Ratings
(Note 1)
Supply Input Voltage ----------------------------------------------------------------------------------------------- 7V
Enable Input Voltage ----------------------------------------------------------------------------------------------- 7V
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 ----------------------------------------------------------------------------------------------- 2.5V to 6V
Enable Input Voltage ----------------------------------------------------------------------------------------------- 0V to 6V
Junction Temperature Range --------------------------------------------------------------------------------------
−
40°C to 125°C
Electrical Characteristics
(V
IN
= V
OUT
+ 1V, C
IN
=C
OUT
= 1μF, C
BP
= 1nF, T
A
= 25° C unless otherwise specified)
Parameter
Output Voltage Accuracy
Current Limit
Quiescent Current
Dropout Voltage
Line Regulation
Load Regulation
Standby Current
(Note 7)
(Note 8)
(Note 5)
(Note 6)
Symbol
ΔV
OUT
I
LIM
I
Q
V
DROP
ΔV
LINE
Test Conditions
I
OUT
= 1mA
R
LOAD
= 1Ω
V
EN
>
1.0V, I
OUT
= 0mA
I
OUT
= 200mA
V
IN
= (V
O UT
+ 0.3V) to 6.0V,
I
OUT
= 1mA
Min
−2
--
--
--
--
--
--
--
--
1.0
--
--
--
--
Typ
--
400
90
200
--
7
0.01
0
--
--
50
−70
−40
150
Max
+2
--
150
300
6
20
1
100
0.4
--
--
--
--
--
Unit
%
mA
μA
mV
mV/V
mV
μA
nA
V
μV
RMS
dB
°C
ΔV
LOA D
1mA
<
I
O UT
<
200mA
I
STBY
I
IBSD
V
IL
V
EN
= GND, Shutdown
V
EN
= GND or VIN
V
IN
= 3V to 5.5V, Shutdown
V
IN
= 3V to 5.5V, Start-Up
10Hz to 100kHz, I
OUT
= 200mA
C
OUT
= 10μF
C
OUT
= 10μF, I
OUT
= 200mA
EN Input Bias Current
Logic-Low Voltage
EN Threshold
Logic-High Voltage V
IH
e
NO
f = 100Hz
f = 10kHz
PSRR
T
SD
Output Noise Voltage
Power Supply
Rejection Rate
Thermal Shutdown Temperature
DS9178-18 April 2011
www.richtek.com
3
RT9178
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.
The dropout voltage is defined as V
IN
-V
OUT
, which is measured when V
OUT
is V
OUT(NORMAL)
−
100mV.
Note 7.
Regulation is measured at constant junction temperature by using a 20ms current pulse. Devices are tested for load
regulation in the load range from 1mA to 200mA.
Note 8.
Standby current is the input current drawn by a regulator when the output voltage is disabled by a shutdown signal
(V
EN
= GND). It is measured with V
IN
= 6V.
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4
DS9178-18 April 2011
RT9178
Typical Operating Characteristics
Output Voltage vs. Temperature
3.5
100
95
Quiescent Current vs. Temperature
Quiescent Current (uA)
Output Voltage (V)
3.3
90
85
80
75
70
3.1
2.9
2.7
V
IN
= 4V
C
BP
= 10nF
C
IN
= 1uF
C
OUT
= 1uF
-35
-15
5
25
45
65
85
105
125
2.5
V
IN
= 4V
C
BP
= 10nF
C
IN
= 1uF
C
OUT
= 1uF
-35
-15
5
25
45
65
85
105
125
Temperature
(
°
C)
Temperature
(
°
C)
0
-10
-20
PSRR
0
-10
-20
PSRR
PSRR(dB)
PSRR (dB)
-30
-40
-50
-60
-70
-80
-90
0.01
0.1
1
100mA
-30
-40
-50
-60
-70
-80
-90
0.01
0.1
1
10
100mA
1mA
1mA
V
IN
= 4V
C
BP
= 10nF
C
IN
= 1uF
C
OUT
= 1uF
T
A
= 25°C
10
100
1000
V
IN
= 4V
C
BP
= 10nF
C
IN
= 1uF
C
OUT
= 1uF
T
A
= -35°C
100
1000
Frequency (kHz)
Frequency (kHz)
Dropout Voltage vs. Load Current
0.3
0.25
Line Transient Response
Input Voltage
Deviation(V)
V
IN
= 3.2 to 3.8V
C
BP
= 10nF
3.8
3.2
C
IN
= 1uF
C
OUT
= 10uF
T
J
= 125°C
Dropout Voltage (V)
0.2
T
J
= 25°C
0.15
Output Voltage
Deviation(mV)
0.1
0.05
0
0
25
50
75
100
125
T
J
= -35°C
V
IN
= 4V
C
BP
= 10nF
C
IN
= 1uF
C
OUT
= 1uF
150
175
200
20
0
-20
Time (500us/Div)
Load Current (mA)
DS9178-18 April 2011
www.richtek.com
5
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