RT9038

®
RT9038
300mA, Low Dropout, Low Noise Ultra-Fast Without
Bypass Capacitor CMOS LDO Regulator
General Description
Features
The RT9038 is a high-performance, 300mA LDO regulator,
offering extremely high PSRR and ultra-low dropout. The
RT9038 is Ideal for portable RF and wireless applications
with demanding performance and space requirements.
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The RT9038 consumes typical 0.7μA in shutdown mode
and has fast turn-on time to be less than 40μs. The other
features include ultra-low dropout voltage, high output
accuracy, current limiting protection, and high ripple
rejection ratio. The RT9038 is available in the WDFN-8L
2x2 package.
Ordering Information
RT9038 Package Type
QW : WDFN-8L 2x2 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Fixed Output Voltage
12 : 1.2V
13 : 1.3V
:
34 : 3.4V
35 : 3.5V
1B : 1.25V
1H : 1.85V
2H : 2.85V
Applications
CDMA/GSM Cellular Handsets
 Portable Information Appliances
 Laptop, Palmtops, Notebook Computers
 Hand-Held Instruments
 Mini PCI & PCI-Express Cards
PCMCIA & New Cards

Pin Configurations
(TOP VIEW)
NC
VOUT
VOUT
VOUT
1
2
3
4
GND
The RT9038 provides quiescent current as low to as 25μA,
further prolonging the battery life. The RT9038 also works
with low-ESR ceramic capacitors, reducing the amount of
board space necessary for power applications, which is
critical in hand-held wireless devices.

Wide Operating Voltage Range : 2.2V to 5.5V
Low Dropout : 125mV at 300mA
Ultra-Low-Noise for RF Application
Ultra-Fast in Line/Load Transient Response
Current Limiting Protection
Thermal Shutdown Protection
High Power Supply Rejection Ratio
Only 1μ
μF Output Capacitor Required for Stability
TTL-Logic-Controlled Shutdown Input
RoHS Compliant and Halogen Free
9
8
7
6
5
GND
EN
VIN
VIN
WDFN-8L 2x2
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Note :
Richtek products are :

RoHS compliant and compatible with the current require-

Suitable for use in SnPb or Pb-free soldering processes.
ments of IPC/JEDEC J-STD-020.
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DS9038-02 July 2015
is a registered trademark of Richtek Technology Corporation.
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RT9038
Typical Application Circuit
VIN
VIN
CIN
1uF
VOUT
COUT
1uF
VOUT
RT9038
Chip Enable
NC
EN
Rpull_down
GND
100k
Functional Pin Description
Pin No.
1
Pin Name
Pin Function
NC
No Internal Connection.
VOUT
Regulator Output.
5, 6
VIN
Supply Input.
7
EN
Chip Enable (Active High). It is recommended to add a 100k resistor between
the EN and GND.
GND
Common Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
2, 3, 4
8,
9 (Exposed Pad)
Function Block Diagram
EN
Current
Limit
POR
OTP
VIN
VREF
+
MOS
Driver
VOUT
GND
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is a registered trademark of Richtek Technology Corporation.
DS9038-02 July 2015
RT9038
Absolute Maximum Ratings
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(Note 1)
Supply Input Voltage -----------------------------------------------------------------------------------------------------EN Input Voltage ----------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C
WDFN-8L 2x2 -------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
WDFN-8L 2x2 -------------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3)
HBM -------------------------------------------------------------------------------------------------------------------------MM ----------------------------------------------------------------------------------------------------------------------------
Recommended Operating Conditions



6V
6V
0.606W
165°C/W
260°C
150°C
−65°C to 150°C
2kV
200V
(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------------ 2.2V to 5.5V
Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = VOUT + 0.5V, VEN = VIN, CIN = COUT = 1uF (Ceramic), TA = 25°C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
2.2
--
5.5
V
Input Voltage Range
VIN
Output Noise Voltage
VON
VOUT = 1.5V, COUT = 1F, IOUT =
0mA
--
30
--
VRMS
Output Voltage Accuracy
(Fixed Output Voltage)
VOUT
IOUT = 10mA
2
0
+2
%
Quiescent Current
IQ
VEN = 5V, IOUT = 0mA
--
25
50
A
Standby Current
ISTBY
VEN = 0V
--
0.7
1.5
A
Current Limit
ILIM
RLOAD = 0, 2.2V  VIN < 5.5V
300
400
600
mA
VDROP
IOUT = 300mA
--
125
240
mV
VLOAD
1mA < IOUT < 300mA
2.2V  VIN  5.5V
--
--
1
%
Logic-Low Voltage VIL
0
--
0.6
Logic-High Voltage VIH
1.6
--
5.5
--
0.1
1
A
--
40
--
dB
Dropout Voltage
(Note 5)
(Note 6)
Load Regulation (Note 7)
(Fixed Output Voltage)
EN Threshold
Enable Pin Current
IEN
Power Supply Rejection Rate
PSRR
IOUT = 100mA, f = 100kHz
Line Regulation
VLINE
VIN = (VOUT + 0.5) to 5.5V,
IOUT = 1mA
Thermal Shutdown Temperature
TSD
--
170
--
Thermal Shutdown Hysteresis
TSD
--
30
--
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DS9038-02 July 2015
--
0.01
0.2
V
%/V
C
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RT9038
Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and 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 may
affect device reliability.
Note 2. θJA is measured at TA = 25°C on a low effective thermal conductivity single-layer test board per JEDEC 51-3.
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 IQ = IIN - IOUT under no
load condition (IOUT = 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 VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) - 100mV.
Note 7. Regulation is measured at constant junction temperature by using a 2ms current pulse. Devices are tested for load
regulation in the load range from 10mA to 300mA.
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DS9038-02 July 2015
RT9038
Typical Operating Characteristics
(CIN = COUT = 1μ/X7R, unless otherwise specified)
Output Voltage vs. Temperature
Quiescent Current vs. Temperature
30
1.60
VIN = 2.5V
1.58
Quiescent Current (μA)
Output Voltage (V)
1.56
1.54
1.52
1.50
1.48
1.46
1.44
26
24
22
20
18
16
14
12
1.42
10
1.40
-50
-25
0
25
50
75
100
-50
125
0
25
50
75
100
Temperature (°C)
Dropout Voltage vs. Load Current
EN Pin Shutdown Response
160
25°C
140
120
100
−40°C
80
60
40
20
VOUT = 2.5V
0
50
100
150
200
250
EN Pin Voltage
(V)
125°C
Output Voltage
(V)
180
0
-25
Temperature (°C)
200
Dropout Voltage (mV)
VIN = 2.5V
28
125
VIN = 2.5V, ILOAD = 50mA
4 VOUT = 1.5V
2
0
2
1
0
300
Time (100μs/Div)
Load Current (mA)
2
0
1.0
0.5
0
Time (5μs/Div)
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DS9038-02 July 2015
Input Voltage
Deviation (V)
4
VIN = 2.5V, ILOAD = 75mA
VOUT = 1.5V
Line Transient Response
Output Voltage
Deviation (mV)
Output Voltage
(V)
EN Pin Voltage
(V)
Start Up
VIN = 2.6V to 3.6V, ILOAD = 10mA
VOUT = 1.5V
3.6
2.6
20
0
-20
Time (100μs/Div)
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RT9038
VIN = 3.0V (By Battery), No Load
300 VOUT = 1.5V
VIN = 2.6V to 3.6V, ILOAD = 100mA
VOUT = 1.5V
3.6
200
Noise (μV)
2.6
20
100
0
-100
0
-200
-20
-300
Time (100μs/Div)
Time (10ms/Div)
Noise
Load Transient Response
VIN = 3.0V (By Battery), ILOAD = 10mA
300 VOUT = 1.5V
200
100
VIN = 2.5V, ILOAD = 10mA to 100mA
100 VOUT = 1.5V
50
0
0
Output Voltage
Deviation (mV)
Noise (μV)
Noise
Load Current
(mA)
Output Voltage
Deviation (mV)
Input Voltage
Deviation (V)
Line Transient Response
-100
-200
-300
Time (10ms/Div)
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50
0
-50
Time (100μs/Div)
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DS9038-02 July 2015
RT9038
Applications Information
Like any low-dropout regulator, the external capacitors used
with the RT9038 must be carefully selected for regulator
stability and performance. Using a capacitor whose value
is > 1μF on the RT9038 input and the amount of
capacitance can be increased without limit. The input
capacitor must be located at a distance of not more than
0.5 inch from the input pin of the IC and returned to a
clean analog ground. Any good quality ceramic can be
used for this capacitor. The capacitor with larger value and
lower ESR (equivalent series resistance) provides better
PSRR and line-transient response.
The output capacitor must meet both requirements for
minimum amount of capacitance and ESR in all LDOs
application. The RT9038 is designed specifically to work
with low ESR ceramic output capacitor in space-saving
and performance consideration. Using a ceramic capacitor
whose value is at least 1μF with ESR is > 20mΩ on the
RT9038 output ensures stability. The RT9038 still works
well with output capacitor of other types due to the wide
stable ESR range. Figure 1. shows the curves of allowable
ESR range as a function of load current for various output
capacitor values. Output capacitor of larger capacitance
can reduce noise and improve load transient response,
stability, and PSRR. The output capacitor should be located
not more than 0.5 inch from the VOUT pin of the RT9038
and returned to a clean analog ground.
Region of Stable COUT ESR vs. Load Current
RegionofofStable
StableCCOUT
OUT ESR
Region
ESR (Ω)
(Ω)
100
1
0.01
Unstable Range
0.001
0
50
100
150
200
250
Load Current (mA)
Figure 1
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DS9038-02 July 2015
is CMOS logic and cannot be left floating.
PSRR
The power supply rejection ratio (PSRR) is defined as the
gain from the input to output divided by the gain from the
supply to the output. The PSRR is found to be


PSRR  20  log ∆Gain Error 
 ∆Supply 
Note that in heavy load measuring, Δsupply will cause
Δtemperature. And Δtemperature will cause Δoutput
voltage. So the temperature effect is include in heavy load
PSRR measuring.
Current limit
The RT9038 contains an independent current limiter, which
monitors and controls the pass transistor's gate voltage,
limiting the output current to 0.4A (typ.). The output can
be shorted to ground indefinitely without damaging the
part.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The
power dissipation definition in the device is calculated as
follows :
0.1
VIN = 5V
CIN = COUT = 1uF/X7R
The RT9038 goes into sleep mode when the EN pin is in
a logic low condition. During this condition, the RT9038
has an EN pin to turn on or turn off the regulator, When
the EN pin is logic hight the regulator will be turned on.
The supply current to 0.7μA typical. The EN pin may be
directly tied to VIN to keep the part on. The Enable input
Thermal protection limits power dissipation in the RT9038.
When the operation junction temperature exceeds 170°C,
the OTP circuit starts the thermal shutdown function and
turns the pass element off. The pass element will be turned
on again after the junction temperature cools by 30°C.
Unstable Range
10
Enable
300
PD = (VIN − VOUT) x IOUT + VIN x IQ
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
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RT9038
junction to ambient. The maximum power dissipation can
be calculated by following formula :
PD(MAX) = ( TJ(MAX) − TA ) /θJA
Where T J(MAX) is the maximum operation junction
temperature, TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For recommended operating conditions specification,
where TJ(MAX) is the maximum junction temperature of the
die (125°C) and TA is the operated ambient temperature.
The junction to ambient thermal resistance for WDFN-8L
2x2 package is 165°C/W on the standard JEDEC 51-3
single-layer thermal test board. The maximum power
dissipation at TA = 25°C can be calculated by following
formula :
PD(MAX) = (125°C − 25°C) / (165°C/W) = 0.606W for
WDFN-8L 2x2 packages
The maximum power dissipation depends on operating
ambient temperature for fixed T J(MAX) and thermal
resistance θJA. The Figure 2 of derating curve allow the
designer to see the effect of rising ambient temperature
on the maximum power allowed.
0.8
Single Layer PCB
Power Dissipation (W)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 2. Derating Curve of Maximum Power Dissipation
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DS9038-02 July 2015
RT9038
Outline Dimension
D2
D
L
E
E2
1
e
SEE DETAIL A
b
2
1
2
1
A
A1
A3
DETAIL A
Pin #1 ID and Tie Bar Mark Options
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
0.700
0.800
0.028
0.031
A1
0.000
0.050
0.000
0.002
A3
0.175
0.250
0.007
0.010
b
0.200
0.300
0.008
0.012
D
1.950
2.050
0.077
0.081
D2
1.000
1.250
0.039
0.049
E
1.950
2.050
0.077
0.081
E2
0.400
0.650
0.016
0.026
e
L
0.500
0.300
0.020
0.400
0.012
0.016
W-Type 8L DFN 2x2 Package
Richtek Technology Corporation
14F, No. 8, Tai Yuen 1st Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789
Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should
obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot
assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be
accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries.
DS9038-02 July 2015
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