®
RT2558
36V, 2μ
μA, IQ, 100mA Low Dropout Voltage Linear Regulator
General Description
Features
The RT2558 is a high voltage linear regulator offering the
benefits of high input voltage, low dropout voltage, low
quiescent current and low external components.
The feature of low quiescent current as low as 2μA is ideal
for powering the battery equipment to a longer service
life. The RT2558 is stable with the ceramic output capacitor
over its wide input range from 3.5V to 36V and the entire
range of output load current (0mA to 100mA).
Ordering Information
RT2558-
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
AEC-Q100 Grade 3 Certification
2μ
μA Quiescent Current
±2% Output Accuracy
100mA Output Current
3.5V to 36V Input Voltage Range
Dropout Voltage : 0.55V at 10mA
Fixed Output Voltage : 2.5V, 3.3V, 5V, 12V
Stable with Ceramic or Tantalum Capacitor
Current Limit Protection
Over-Temperature Protection
SOP-8 (Exposed Pad) Package
RoHS Compliant and Halogen Free
Applications
Lead Plating System
G : Green (Halogen Free and Pb Free)
Output Voltage
25 : 2.5V
33 : 3.3V
50 : 5V
C0 : 12V
Portable, Battery Powered Equipment
Ultra Low Power Microcontrollers
Notebook Computers
Pin Configurations
Note :
(TOP VIEW)
Richtek products are :
RoHS compliant and compatible with the current require-
8
VCC
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
NC
2
VOUT
3
NC
4
GND
NC
7
GND
6
NC
5
NC
9
SOP-8 (Exposed Pad)
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
Simplified Application Circuit
RT2558
VCC
VCC
VOUT
VOUT
GND
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS2558-02 April 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1
RT2558
Functional Pin Description
Pin No.
1
Pin Name
Pin Function
VCC
Supply Voltage Input.
NC
No Internal Connection.
3
VOUT
Regulator Output.
7, 9 (Exposed Pad)
GND
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
2, 4, 5, 6, 8
Function Block Diagram
VOUT
VCC
Bandgap
Reference
R1
-
+
OCP
OTP
GND
R2
Operation
The RT2558 is a high input voltage linear regulator designed
specially for low external components system. The input
voltage range is from 3.5V to 36V.
Output Transistor
The RT2558 builds in a P-MOSFET output transistor which
provides a low switch-on resistance for low dropout voltage
applications.
Error Amplifier
The Error Amplifier compares the internal reference voltage
with the output feedback voltage from the internal divider,
and controls the Gate voltage of P-MOSFET to support
good line regulation and load regulation at output voltage.
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2
Current Limit
The RT2558 provides current limit function to prevent the
device from damages during over-load or short-circuit
condition. This current is detected by an internal sensing
transistor.
Over-Temperature Protection
The over-temperature protection function will turn off the
P-MOSFET when the junction temperature exceeds
150°C (typ.). Once the junction temperature cools down
by approximately 20°C, the regulator will automatically
resume operation.
is a registered trademark of Richtek Technology Corporation.
DS2558-02 April 2014
RT2558
Absolute Maximum Ratings
(Note 1)
VCC to GND --------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C
SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2)
SOP-8 (Exposed Pad), θJA --------------------------------------------------------------------------------------------SOP-8 (Exposed Pad), θJC -------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------------------Junction Temperature ---------------------------------------------------------------------------------------------------Storage Temperature Range ------------------------------------------------------------------------------------------ESD Susceptibility (Note 3)
HBM (Human Body Model) ---------------------------------------------------------------------------------------------
Recommended Operating Conditions
−0.3V to 40V
2.041W
49°C/W
8°C/W
260°C
150°C
−65°C to 150°C
2kV
(Note 4)
Supply Input Voltage, VCC --------------------------------------------------------------------------------------------- 3.5V to 36V
Junction Temperature Range ------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range ------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
((VOUT + 1V) < VCC < 36V, TA = −40°C to 85°C, unless otherwise specified.)
Parameter
DC Output Voltage
Dropout Voltage
Symbol
VOUT
VDROP
Test Conditions
IOUT = 10mA
Min
Typ
Max
VOUT = 3.3V
3.234
--
3.366
VOUT = 2.5V
2.45
--
2.55
VOUT = 5V
4.9
--
5.1
VOUT = 12V
11.79
--
12.24
--
0.32
0.55
--
2
3.5
--
3.5
5
--
0.04
0.5
%
0.5
--
0.5
%
115
175
300
mA
IOUT = 10mA
Unit
V
V
VOUT = 3.3V
VCC Quiescent Current
IQ
IOUT = 0mA, VCC = 12V
VOUT = 5V
IOUT = 0mA, VCC = 24V
Line Regulation
VLINE
VOUT = 2.5V
VOUT = 12V
IOUT = 10mA
A
VOUT = 3.3V
Load Regulation
VLOAD
0mA < IOUT < 50mA,
VCC = 12V
VOUT = 5V
0mA < IOUT < 50mA,
VCC = 24V
Output Current Limit
ILIM
VOUT = 2.5V
VOUT = 12V
VOUT = 3.3V
VOUT = 0.5 x VOUT(normal),
VOUT = 2.5V
VCC = 12V
VOUT = 5V
VOUT = 0.5 x VOUT(normal),
VOUT = 12V
VCC = 24V
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS2558-02 April 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3
RT2558
Parameter
Symbol
Thermal Shutdown
Temperature
(Junction Temperature)
TSD
Thermal Shutdown
Hysteresis
TSD
Test Conditions
IOUT = 30mA
Min
Typ
Max
Unit
--
150
--
C
--
20
--
C
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 high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is
measured at the exposed pad of the package. The PCB copper area with exposed pad is 70mm2.
Note 3. Devices are ESD sensitive. Handling precaution is recommended.
Note 4. The device is not guaranteed to function outside its operating conditions.
Typical Application Circuit
RT2558
VCC
1
VCC
1µF
VOUT
3
VOUT
1µF
GND
7, 9 (Exposed Pad)
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is a registered trademark of Richtek Technology Corporation.
DS2558-02 April 2014
RT2558
Typical Operating Characteristics
Output Voltage vs. Input Voltage
3.320
3.33
3.315
3.32
3.310
Output Voltage (V)
Output Voltage (V)
Output Voltage vs. Temperature
3.34
3.31
3.30
VCC = 24V
VCC = 12V
3.29
3.28
3.305
3.300
3.295
3.290
3.27
3.285
VOUT = 3.3V
VOUT = 3.3V, IOUT = 0.01A
3.26
3.280
-50
-25
0
25
50
75
100
125
4
8
12
Temperature (°C)
3.5
2.15
3.0
2.5
VCC = 36V
VCC = 12V
VCC = 4V
1.0
0.5
28
32
36
2.10
2.05
2.00
1.95
1.90
1.85
VOUT = 3.3V
VOUT = 3.3V, IOUT = 0A
0.0
1.80
-50
-25
0
25
50
75
100
125
4
8
12
Temperature (°C)
16
20
24
28
32
36
Input Voltage (V)
Output Current Limit vs. Temperature
Output Current Limit vs. Input Voltage
300
Output Current Limit (mA)
300
Output Current Limit (mA)
24
Quiescent Current vs. Input Voltage
2.20
Quiescent Current (µA)
Quiescent Current (µA)
Quiescent Current vs. Temperature
1.5
20
Input Voltage (V)
4.0
2.0
16
250
200
VCC = 24V
VCC = 12V
150
100
50
250
200
150
100
50
VOUT = 3.3V
0
VOUT = 3.3V
0
-50
-25
0
25
50
75
100
Temperature (°C)
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS2558-02 April 2014
125
4
8
12
16
20
24
28
32
36
Input Voltage (V)
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RT2558
PSRR vs. Frequency
Dropout Voltage vs. Load Current
0
5
4
-20
TA = 125°C
TA = 25°C
TA = −40°C
3
-30
PSRR (dB)
Dropout Voltage (V)
-10
2
-40
-50
IOUT = 25mA
IOUT = 10mA
-60
-70
-80
1
VOUT = 3.3V
-90
VCC = 12V, VOUT = 3.3V
-100
0
0
10
20
30
40
50
60
70
80
90
100
10000
100000
Load Transient Response
Load Transient Response
1000000
VOUT
(50mV/Div)
VCC = 12V, VOUT = 3.3V, IOUT = 0 to 100mA
IOUT
(50mA/Div)
VCC = 12V, VOUT = 3.3V, IOUT = 0 to 50mA
Time (1ms/Div)
Time (1ms/Div)
Power On from VCC
Power Off from VCC
V CC
(5V/Div)
VOUT
(2V/Div)
VOUT
(2V/Div)
VCC = 12V, VOUT = 3.3V, IOUT = 100mA
Time (5ms/Div)
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1000
Frequency (Hz)
V CC
(5V/Div)
IOUT
(100mA/Div)
100
Load Current (mA)
VOUT
(50mV/Div)
IOUT
(50mA/Div)
10
IOUT
(100mA/Div)
VCC = 12V, VOUT = 3.3V, IOUT = 100mA
Time (25ms/Div)
is a registered trademark of Richtek Technology Corporation.
DS2558-02 April 2014
RT2558
Ground Current vs. Load Current
Ground Current (µA)
200
150
100
50
Rising, TA = 25°C
Rising, TA = −40°C
Rising, TA = 125°C
Falling, TA = 25°C
Falling, TA = −40°C
Falling, TA = 125°C
VCC = 12V,
VOUT = 3.3V
0
0.001
0.01
0.1
1
10
100
1000
Load Current (mA)
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS2558-02 April 2014
is a registered trademark of Richtek Technology Corporation.
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RT2558
Application Information
Capacitor Selection
Like any low dropout linear regulator, the RT2558’s
external input and output capacitors must be properly
selected for stability and performance. Use a 1μF or larger
input capacitor and place it close to the IC's VCC and
GND pins. Any output capacitor met the minimum 1mΩ
ESR (Equivalent Series Resistance) requirement may be
used. Place the output capacitor close to the IC's VOUT
and GND pins. Increasing capacitance and decreasing ESR
can improve the circuit's PSRR and line transient response.
Over-Temperature Protection
Thermal protection limits power dissipation to prevent IC
overheat. When the operation junction temperature
exceeds 150°C, the over-temperature protection circuit
starts the thermal shutdown function and turns the
regulator off. The regulator turns on again after the junction
temperature cools down by 20°C.
Power Dissipation
For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The
power dissipation definition in device is :
PD = (VIN − VOUT) x IOUT + VIN x IQ
The maximum power dissipation at TA = 25°C can be
calculated by following formula :
P D(MAX) = (125°C − 25°C) / (75°C/W) = 1.33W
(SOP-8 Exposed Pad on the minimum layout)
P D(MAX) = (125°C − 25°C) / (49°C/W) = 2.04W
(SOP-8 Exposed Pad on the 70mm2 copper area layout)
Layout Considerations
The thermal resistance θJA of SOP-8 (Exposed Pad) is
determined by the package design and the PCB design.
However, the package design had been designed. If
possible, it's useful to increase thermal performance by
the PCB design. The thermal resistance θJA can be
decreased by adding a copper under the exposed pad of
SOP-8 (Exposed Pad) package.
As shown in Figure 1, the amount of copper area to which
the SOP-8 (Exposed Pad) is mounted affects thermal
performance. When mounted to the standard SOP-8
(Exposed Pad) pad (Figure 1.a), θJA is 75°C/W. Adding
copper area of pad under the SOP-8 (Exposed Pad) (Figure
1.b) reduces the θJA to 64°C/W. Even further, increasing
the copper area of pad to 70mm2 (Figure 1.e) reduces the
θJA to 49°C/W.
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junctions to ambient. The maximum power dissipation can
be calculated by following formula :
PD(MAX) = (TJ(MAX) − TA) / θJA
(a) Copper Area = (2.3 x 2.3) mm2, θJA = 75°C/W
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, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance for SOP-8 (Exposed Pad)
package is 75°C/W on the standard JEDEC 51-7 (4 layers,
2S2P) thermal test board. The copper thickness is 2oz.
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(b) Copper Area = 10mm2, θJA = 64°C/W
is a registered trademark of Richtek Technology Corporation.
DS2558-02 April 2014
RT2558
The maximum power dissipation depends on operating
ambient temperature for fixed T J(MAX) and thermal
resistance θJA. The Figure 2 of derating curves allows the
designer to see the effect of rising ambient temperature
on the maximum power allowed.
(C) Copper Area = 30mm2, θJA = 54°C/W
2.2
(d) Copper Area = 50mm2, θJA = 51°C/W
Power Dissipation (W)
2.0
1.8
Copper Area
70mm2
50mm2
30mm2
10mm2
Min. Layout
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
JEDEC 4-Layer PCB
0.0
0
20
40
60
80
100
120
140
Ambient Temperature (°C)
Figure 2. Derating Curve for Package
(e) Copper Area = 70mm2, θJA = 49°C/W
Figure 1. Thermal Resistance vs. Copper Area Layout
Thermal Design
Copyright © 2014 Richtek Technology Corporation. All rights reserved.
DS2558-02 April 2014
is a registered trademark of Richtek Technology Corporation.
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RT2558
Outline Dimension
H
A
M
EXPOSED THERMAL PAD
(Bottom of Package)
Y
J
X
B
F
C
I
D
Dimensions In Millimeters
Dimensions In Inches
Symbol
Min
Max
Min
Max
A
4.801
5.004
0.189
0.197
B
3.810
4.000
0.150
0.157
C
1.346
1.753
0.053
0.069
D
0.330
0.510
0.013
0.020
F
1.194
1.346
0.047
0.053
H
0.170
0.254
0.007
0.010
I
0.000
0.152
0.000
0.006
J
5.791
6.200
0.228
0.244
M
0.406
1.270
0.016
0.050
X
2.000
2.300
0.079
0.091
Y
2.000
2.300
0.079
0.091
X
2.100
2.500
0.083
0.098
Y
3.000
3.500
0.118
0.138
Option 1
Option 2
8-Lead SOP (Exposed Pad) Plastic 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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DS2558-02 April 2014
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