RT9041A/B

®
RT9041A/B
500mA, Low Voltage, LDO Regulator with External Bias
Supply
General Description
Features
The RT9041A/B are low voltage, low dropout linear
regulators with an external bias supply input. The bias
supply drives the gate of the internal N-Channel pass
transistor, making these devices ideal for applications that
require low voltage outputs from low voltage inputs.
RT9041A and RT9041B provide the fixed version from 1V
to 2V with 0.1V increment. Besides, RT9041B provides
more feature by using external resistors as adjustable
output voltage. The RT9041A/B include a current limit and
thermal shutdown that protects the regulator in the event
of a fault condition.

The RT9041A/B is available in a SOT-23-6 package.









RT9041
-
Output Voltage
Fixed Only (RT9041A)
Fixed & Adjustable (RT9041B)
10 : 1.0V/Adj
11 : 1.1V/Adj
:
19 :1.9V/Adj
20 : 2.0V/Adj
Note :
A : Fixed with PGOOD
B : Fixed/Adjustable
Richtek products are :

RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.




Package Type
E : SOT-23-6
Lead Plating System
G : Green (Halogen Free and Pb Free)
Suitable for use in SnPb or Pb-free soldering processes.
No Minimum Load Current Required
1V to 5.5V Input Supply Voltage
3V to 5.5V Input Bias Supply Voltage
PGOOD Open-Drain Output (RT9041A)
Support both Fixed/Adjustable Mode (RT9041B)
Low Supply Current
5μ
μA (max) Shutdown Supply Current
RoHS Compliant and Halogen Free
Applications

Ordering Information
±2% Output Voltage Accuracy
Notebook Computers
VID Power Supplies
PDAs
Cell Phones
Low Dropout Regulators with External Bias Supply
Pin Configurations
(TOP VIEW)
VIN VOUT PGOOD
6
5
4
2
3
VDD GND EN
RT9041A
VIN VOUT ADJ
6
5
4
2
3
VDD GND EN
RT9041B
SOT-23-6
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS9041A/B-04 November 2014
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RT9041A/B
Typical Application Circuit
RT9041A
VDD
3V to 5.5V
1
VIN
VDD
CVDD
0.1µF 2
GND
3
Chip Enable
VOUT
6
CIN
10µF
5
COUT
10µF
VIN
1V to 5.5V
VOUT
PGOOD 4
EN
100k
RT9041B
VDD
3V to 5.5V
1
CVDD
0.1µF
VIN 6
CIN
10µF
2 GND
3
Chip Enable
VDD
VOUT 5
VIN
1V to 5.5V
VOUT
EN
R1
ADJ 4
R2
COUT
10µF
Function Pin Description
Pin No.
Pin Name
Pin Function
RT9041A
RT9041B
1
1
VDD
Supply Voltage of Control Circuitry.
6
6
VIN
Supply Input Voltage.
5
5
VOUT
Output Voltage.
3
3
EN
Chip Enable (Active-High).
2
2
GND
Ground.
4
--
PGOOD
Power Good Open Drain Output.
--
4
ADJ
Set the output voltage by the internal feedback resistors when ADJ is
grounded. If external feedback resistors is used, VOUT = VREF x (R1 + R2)/R2.
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DS9041A/B-04 November 2014
RT9041A/B
Function Block Diagram
VOUT
VIN
Driver
OTP
+
VIN
EN
POR
VDD
-
OCP
Error
Amplifier
PGOOD
0.8V
-
0.7V
+
GND
RT9041A
VOUT
VIN
Driver
OTP
+
VIN
EN
POR
VDD
-
OCP
Error
Amplifier
0.8V
Mode
ADJ
GND
RT9041B
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RT9041A/B
Absolute Maximum Ratings









(Note 1)
Supply Input Voltage, VDD ---------------------------------------------------------------------------------------------Input Voltage, VIN --------------------------------------------------------------------------------------------------------Other Input/Output Pins ------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C
SOT-23-6 -------------------------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
SOT-23-6, θJA --------------------------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note3)
HBM (Human Body Model) ----------------------------------------------------------------------------------------------
Recommended Operating Conditions




6V
6V
6V
0.4W
250°C/W
260°C
150°C
−65°C to 150°C
2kV
(Note 4)
Supply Input Voltage, VIN ----------------------------------------------------------------------------------------------- 1V to 5.5V
Control Voltage, VDD ----------------------------------------------------------------------------------------------------- 3V to 5.5V
Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 1.8V, ILOAD = 1mA, COUT = 10μF, TA = 25°C unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
VOUT
1
--
2
V
VOUT
0.8
--
2.5
V
--
2.7
--
V
Input
Output Voltage Range
(for RT9041A only)
Output Voltage Range
(for RT9041B only)
Bias Input Under Voltage Lockout
ISHDN
IQ
ISHDN
1V < VIN < 5.5V, VIN = VOUT + 0.6V
--
1
5
A
3V < VDD < 5.5V
--
160
250
A
3V < VDD < 5.5V
--
1
5
A
Line Regulation
VOUT / VIN
0.15
--
0.15
%/V
Load Regulation
VOUT / IIN
IOUT = 10mA, 1.5V < VIN < 5.5V,
VIN = VOUT + 0.6V
VIN = VOUT + 0.6V,
IOUT = 1mA to 500mA
--
0.2
1
%
Output Voltage Accuracy
(RT9041A)
Output Voltage Accuracy
(RT9041B)
VOUT
VIN = VOUT + 0.6V, IOUT = 10mA
2
--
2
%
VOUT
VIN = VOUT + 0.6V, IOUT = 10mA,
Short ADJ to GND
2
--
2
%
0.784
0.8
0.816
V
ILOAD = 300mA, VDDVOUT  2.1V
--
200
300
mV
ILOAD = 500mA, VDDVOUT  2.1V
--
300
500
mV
VIN Shutdown Current
Quiescent Current
VDD Shutdown Current
Regulator Characteristics
Reference Voltage (RT9041B)
Dropout Voltage
IOUT = 10mA
VDROP
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DS9041A/B-04 November 2014
RT9041A/B
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
550
700
1400
mA
--
160
--
°C
--
20
--
°C
--
0.2
--
V
% of regulated output voltage
--
88
--
%
(Note 5)
--
10
--
mV
Current Limit
ILIM
RLOAD = 0
Thermal-Shutdown Temp
TSD
3V < VBIAS < 5.5V
Thermal-Shutdown Hysteresis
TSD
ADJ
ADJ Pin Threshold (RT9041B)
PGOOD Comparator
Comparator Threshold
Comparator Hysteresis
VHYST
Logic and I/O
EN Input Voltage
Logic-High
VIH
1.6
--
--
V
Logic-Low
VIL
--
--
0.8
V
VEN = 5V
--
12
--
A
PGOOD sinking 1mA
--
--
0.1
V
0 < VPGOOD < VIN
1
--
1
A
Rising edge within 5% of
regulation level
1
--
5
ms
EN Current
PGOOD Output Low Voltage
(RT9041A)
PGOOD Output High Leakage
Current (RT9041A)
Dynamics
PGOOD Propagation Delay
(RT9041A)
IEN
tPGOOD
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. Guaranteed by design.
Copyright © 2013 Richtek Technology Corporation. All rights reserved.
DS9041A/B-04 November 2014
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RT9041A/B
Typical Operating Characteristics
Reference Voltage vs. Temperature
0.84
2.15
0.83
Reference Voltage (V)
Output Voltage (V)
Output Voltage vs. Temperature
2.20
2.10
2.05
2.00
1.95
1.90
0.82
0.81
0.80
0.79
0.78
0.77
1.85
VDD = 5V, VIN = 3.3V, VOUT = 2V, IOUT = 0mA
1.80
-50
-25
0
25
50
75
100
VDD = 5V, VIN = 3.3V, VADJ = 0.8V, IOUT = 0mA
0.76
-50
125
-25
0
25
210
0.90
200
0.85
190
0.80
Current Limit (A)
Quiescent Current (μA)1
75
100
125
Current Limit vs. Temperature
Quiescent Current vs. Temperature
180
170
160
150
140
0.75
0.70
0.65
0.60
0.55
VDD = 5V, VIN = 3.3V, VOUT = 2V, IOUT = 0mA
130
-50
-25
0
25
50
75
100
VDD = 5V, VIN = 3.3V, VOUT = 2V, IOUT = 0mA
0.50
125
-50
-25
0
25
50
75
100
125
Temperature (°C)
Temperature (°C)
Dropout Voltage vs. Output Current
EN Threshold Voltage vs. Temperature
1.6
600
125°C
400
25°C
300
−40°C
200
100
Threshold Voltage (V)
1.5
500
Dropout Voltage (mV)
50
Temperature (°C)
Temperature (°C)
Rising
1.4
1.3
Falling
1.2
1.1
1.0
0.9
VDD = 5V
0
0
100
200
300
400
Output Current (mA)
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500
VDD = 5V, VOUT = 1V
0.8
-50
-25
0
25
50
75
100
125
Temperature (°C)
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DS9041A/B-04 November 2014
RT9041A/B
VDD UVLO vs. Temperature
VIN UVLO vs. Temperature
1.0
3.0
0.9
0.8
Rising
2.6
2.4
UVLO (V)
UVLO (V)
2.8
Falling
2.2
0.7
0.6
Falling
0.5
VDD = 5V, VOUT = 1V
2.0
-50
-25
0
25
50
75
100
VDD = 5V, VOUT = 1V
0.4
125
-50
-25
0
25
50
75
Temperature (°C)
Temperature (°C)
PGOOD Timing vs. Temperature
PGOOD Response
5
PGOOD Timing (ms)
Rising
100
125
Rising
VEN
(5V/Div)
4
3
VOUT
(1V/Div)
2
1
VDD = 5V, VIN = 3.3V, VOUT = 1V
0
-50
-25
0
25
50
75
100
PGOOD
(1V/Div)
VDD = 5V, VIN = 4V, IOUT = 40mA
Time (2.5ms/Div)
125
Temperature (°C)
Load Transient Response
VDD = 5V, VIN = 3.3V, VOUT = 2V
IOUT = 10mA to 0.5A
Line Transient Response
4
VIN
(V) 3
IOUT
(500mA/Div)
VOUT
(50mV/Div)
VOUT
(5mV/Div)
VDD = 5V, VIN = 3V to 4V, VOUT = 1V, IOUT = 10mA
Time (100μs/Div)
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DS9041A/B-04 November 2014
Time (500μs/Div)
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RT9041A/B
Line Transient Response
EN Response
VDD = 5V, VIN = 3.3V, VOUT = 1V, IOUT = 0.5A
4
VIN
(V) 3
VEN
(5V/Div)
VOUT
(5mV/Div)
VDD = 5V, VIN = 3V to 4V, VOUT = 1V, IOUT = 100mA
0
VOUT
(500mV/Div)
Time (500μs/Div)
Time (500μs/Div)
PSRR
Noise
VDD = VIN = 4.5V (By Battery),
VOUT = 1V, IOUT = 1mA
VDD = 5V, VIN = 3.3V to 3.4V, CIN = 1μF, COUT = 10μF
PSRR (dB)
-20
-40
VOUT
(200μV/Div)
IOUT = 10mA
IOUT = 100mA
-60
-80
-100
10
10
100
100
1000
1k
10000
10k
100000
100k
1000000
1M
Time (10ms/Div)
Frequency (Hz)
Noise
VDD = VIN = 4.5V (By Battery),
VOUT = 1V, IOUT = 10mA
VOUT
(200μV/Div)
Time (10ms/Div)
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DS9041A/B-04 November 2014
RT9041A/B
Application Information
The RT9041A/B is a low voltage, low dropout linear
regulator with an external bias supply input, capable of
supporting an input voltage range from 1V to 5.5V with a
fixed output voltage from 1V to 2V in 0.1V increments.
Supply Voltage Setting
The bias supply voltage (VDD) operates from 3V to 5.5V.
For better efficiency, it is suggested to operate VDD at 5V
when the output voltage is higher than 1V. Figure 1 shows
the curves of the recommended VDD − VOUT range vs. the
dropout voltage (VIN − VOUT) values.
Dropout Voltage vs. VDD - VOUT
Dropout Voltage (mV)
400
350
IO = 500mA
250
200
IO = 300mA
100
50
0
2.0
2.2
2.4
2.6
2.8
3.0
3.2
3.4
error amplifier, and band gap are all turned off, reducing
the supply current to 1μA (typ.). The EN pin can be directly
tied to VIN to keep the part on.
Current Limit
The RT9041A/B contains an independent current limit
circuitry, which monitors and controls the pass transistor’s
gate voltage, limiting the output current to 0.7A (typ.).
Like any low dropout regulator, the external capacitors of
the RT9041A/B must be carefully selected for regulator
stability and performance. Using a capacitor of at least
10μF is suitable. The input capacitor must be located at a
distance of not more than 0.5 inch from the input pin of
the IC. Any good quality ceramic capacitor can be used.
However, a capacitor with larger value and lower ESR
(Equivalent Series Resistance) is recommended since it
will provide better PSRR and line transient response.
450
150
The RT9041A/B goes into sleep mode when the EN pin is
in a logic low condition. In this condition, the pass transistor,
CIN and COUT Selection
500
300
Chip Enable Operation
3.6
3.8
4.0
VDD - VOUT (V)
Figure 1. Dropout Voltage vs. VDD − VOUT
Output Voltage Setting
The RT9041B output voltage is also adjustable from 0.8V
to 2.5V via the external resistive voltage divider. The voltage
divider resistors can have values up to 800kΩ because of
the very high impedance and low bias current of the sense
comparator. The output voltage is set according to the
following equation :
VOUT = VREF x  1 + R1 

R2 
The RT9041A/B is designed specifically to work with low
ESR ceramic output capacitor for space saving and
performance consideration. Using a ceramic capacitor with
value at least 10μF and ESR larger than 2mΩ on the
RT9041A/B output ensures stability. Nevertheless, the
RT9041A/B can still work well with other types of output
capacitors due to its wide range of stable ESR. Figure 2
shows the allowable ESR range as a function of load
current for various output capacitance. Output capacitors
with larger capacitance can reduce noise and improve load
transient response, stability, and PSRR. The output
capacitor should be located at a distance of not more than
0.5 inch from the output pin of the RT9041A/B.
where VREF is the reference voltage with a typical value of
0.8V.
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RT9041A/B
Region of Stable COUT ESR vs. Load Current
Unstable Range
10.000
Stable Range
1.000
0.45
0.100
VDD = 5V, VIN = 2.5V, VOUT = 1V,
CVDD = 0.1μF, CIN = COUT = 10μF/X7R
0.010
Simulation Verify
0.001
0
100
200
300
400
500
Load Current (mA)
Figure 2. Region of Stable COUT ESR vs. Load Current
Maximum Power Dissipation (W)1
(Ω)
Region of Stable COUT ESR (Ω)
100.000
The maximum power dissipation depends on the operating
ambient temperature for fixed T J(MAX) and thermal
resistance, θJA. The derating curve in Figure 3 allows the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
Four-Layer PCB
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
Thermal Considerations
For continuous operation, do not exceed absolute
maximum junction temperature. The maximum power
dissipation depends on the thermal resistance of the IC
package, PCB layout, rate of surrounding airflow, and
difference between junction and ambient temperature. The
maximum power dissipation can be calculated by the
following formula :
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 3. Derating Curve of Maximum Power Dissipation
PD(MAX) = (TJ(MAX) − TA) / θJA
where TJ(MAX) is the maximum junction temperature, TA is
the ambient temperature, and θJA is the junction to ambient
thermal resistance.
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
SOT-23-6 packages, the thermal resistance, θJA, is 250°C/
W on a standard JEDEC 51-3 single-layer thermal test
board. The maximum power dissipation at TA = 25°C can
be calculated by the following formula :
PD(MAX) = (125°C − 25°C) / (250°C/W) = 0.400W for
SOT-23-6 package
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DS9041A/B-04 November 2014
RT9041A/B
Outline Dimension
H
D
L
C
B
b
A
A1
e
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
0.889
1.295
0.031
0.051
A1
0.000
0.152
0.000
0.006
B
1.397
1.803
0.055
0.071
b
0.250
0.560
0.010
0.022
C
2.591
2.997
0.102
0.118
D
2.692
3.099
0.106
0.122
e
0.838
1.041
0.033
0.041
H
0.080
0.254
0.003
0.010
L
0.300
0.610
0.012
0.024
SOT-23-6 Surface Mount 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.
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