DS2517B 01

®
RT2517B
1A, 6V, Ultra-Low Dropout Linear Regulator
General Description
Features
The RT2517B is a high performance positive voltage
regulator designed for use in applications requiring ultralow input voltage and ultra-low dropout voltage at up to
1A. The feature of ultra-low dropout voltage is ideal for the
application where output voltage is very close to input
voltage. The input voltage can be as low as 2.2V and the
output voltage is adjustable by an external resistive divider.
The RT2517B provides an excellent output voltage
regulation over variations in line, load and temperature.
Current limit and thermal shutdown protection functions
are provided. Additionally, an enable pin is designed to
further reduce power consumption while shutdown and
the shutdown current is as low as 1.5μA.

AEC-Q100 Grade3 Certification

Input Voltage Range : 2.2V to 6V
VOUT Range from 1.2V to VIN − VDROP
Reference Voltage : 1.2V ±2% over −40°°C to 85°°C
Ultra-Low Dropout Voltage : 200mV at 1A over
−40°°C to 85°°C
Low Quiescent 1.5μ
μA in Shutdown Mode
Soft Discharge Functionality
Thermal Shutdown and Current Limit
RoHS Compliant and Halogen Free
The RT2517B is available in the SOP-8 (Exposed Pad)
package.
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Applications
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Ordering Information
Automotive Audio, Navigation, & Info systems
Industrial Grade General Purpose Point of Load
Digital Set top Boxes
Vehicle Electronics
Marking Information
RT2517B
RT2517BGSP : Product Number
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
RT2517B
GSPYMDNN
YMDNN : Date Code
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Pin Configurations
Richtek products are :

(TOP VIEW)
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

IC
Suitable for use in SnPb or Pb-free soldering processes.
8
EN
2
VIN
3
VIN
4
GND
GND
7
ADJ
6
VOUT
5
VOUT
9
SOP-8 (Exposed Pad)
Simplified Application Circuit
VIN
VIN
RT2517B
VOUT
EN
ADJ
C1
Enable
R1
GND
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DS2517B-01 March 2015
VOUT
C2
R2
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RT2517B
Functional Pin Description
Pin No.
Pin Name
Pin Function
1
IC
Internal Connection. Leave floating and do not make connection to this pin.
2
EN
Chip Enable (Active High). This pin will be pulled up by internal circuit if this pin is
open.
3,4
VIN
Supply Voltage Input. Connect a minimum 10F ceramic capacitor at this pin.
5,6
VOUT
Output Voltage. A minimum 10F capacitor should be placed directly at this pin.
ADJ
Feedback Voltage Input. Connect an external resistor divider to this pin for output
voltage setting. If this pin is connected to the VOUT pin, the output voltage will be
set at 1.2V.
7
8,
GND
9 (Exposed pad)
Ground. The exposed pad must be soldered to a large PCB and connected to GND
for maximum the power dissipation.
Function Block Diagram
RSENSE
VOUT
VIN
VPUMP
-
-
+
+
ADJ
VIN
EN
VIN
Thermal
Shutdown
VOUT
+
VIN
-
GND
Reverse Voltage
Shutdown
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Reference
Generator
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DS2517B-01 March 2015
RT2517B
Operation
The RT2517B is a linear regulator designed specially for
ultra-low dropout voltage. The input voltage range is from
2.2V to 6V.
Output Transistor
The RT2517B builds in a 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 MOSFET to support good
line regulation and load regulation at output voltage.
Reference Generator
The RT2517B provides a reference voltage by internal
reference generator circuit. The reference voltage can be
used to determine the output voltage.
Thermal Shutdown
The thermal shutdown function will turn off the MOSFET
when the junction temperature exceeds 160°C (typ.).
Once the junction temperature cools down by
approximately 10°C, the regulator will automatically
resume operation.
Current Limit
The RT2517B 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
device
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RT2517B
Absolute Maximum Ratings
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(Note 1)
Supply Voltage, VIN -----------------------------------------------------------------------------------------------------Other Pins ------------------------------------------------------------------------------------------------------------------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
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−0.3V to 7V
−0.3V to 6V
2.041W
49°C/W
8°C/W
260°C
150°C
−65°C to 150°C
2kV
(Note 4)
Supply Input Voltage, VIN ----------------------------------------------------------------------------------------------- 2.2V to 6V
Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C
Electrical Characteristics
(VIN = 2.2V to 6V, IOUT = 10μA to 1A, VADJ = VOUT , −40°C ≤ TA ≤ 85°C, unless otherwise specified)
Parameter
Symbol
Test Conditions
Min
Typ
Max
Unit
--
1
10
A
Shutdown Supply Current
I SHDN
VIN = 3.3V, VEN = 0V
Quiescent Current
IQ
VIN = 3.3V, IOUT = 0A
--
0.7
1.5
mA
Line Regulation
VLINE
IOUT = 10mA
--
--
0.4
%/V
Load Regulation
VLOAD
IOUT = 10mA to 1A
--
--
1
%
Current Limit
I LIM
VIN = 3.3V
1.05
--
2.8
A
Current Foldback Threshold
VFold
VIN = 3.3V
0.3
--
0.5
V
Dropout Voltage
VDROP
IOUT = 1A,
--
--
400
mV
ADJ Reference Voltage
VADJ
VIN = 3.3V, VADJ = VOUT , IOUT = 10mA 1.176
1.2
1.224
V
ADJ Pin Current
I ADJ
VIN = 3.3V
--
--
400
nA
Logic-High
VIH
VIN = 3.3V
1.6
--
--
Logic-Low
VIL
VIN = 3.3V
--
--
0.4
I EN
VIN = 6V, VEN = 0V
--
--
1
A
--
160
--
C
--
10
--
C
EN Input Voltage
Enable Pin Current
Thermal Shutdown Temperature T SD
Thermal Shutdown Hysteresis
TSD
V
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.
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DS2517B-01 March 2015
RT2517B
Typical Application Circuit
RT2517B
VIN
3, 4
VIN
VOUT
C1
10µF
Enable
R1
10k
2
ADJ 7
EN
VOUT
1.8V/1A
5, 6
C2
10µF
R2
20k
GND
8,
9 (Exposed Pad)
Figure 1. 1.8V Output Voltage Operation Circuit
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RT2517B
Typical Operating Characteristics
Quiescent Current vs. Temperature
Reference Voltage vs. Temperature
1.15
Quiescent Current (mA)
Reference Voltage (V)
1.210
1.205
VIN = 5V
VIN = 3.3V
1.200
1.195
1.190
0.95
VIN = 5V
0.75
VIN = 3.3V
0.55
VOUT = 1.8V
VOUT = 1.8V
0.35
1.185
-50
-25
0
25
50
75
100
-50
125
-25
0
50
75
Shutdown Current vs. Temperature
125
UVLO vs. Temperature
1.8
1.7
1.4
1.6
UVLO (V)
Rising
1.0
VIN = 5V
VIN = 3.3V
0.6
1.5
1.4
Falling
VOUT = 1.8V
VEN = 5V
0.2
1.3
-50
-20
10
40
70
100
130
-50
-25
0
Temperature (°C)
25
50
75
100
125
Temperature (°C)
EN Threshold Voltage vs. Temperature
Dropout Voltage vs. IOUT
1.3
EN Threshold Voltage (V)
180
Dropout Voltage (mV)
100
Temperature (°C)
Temperature (°C)
Shutdown Current (µA)1
25
150
120
90
60
125°C
25°C
−40°C
30
1.2
Rising
1.1
1.0
Falling
0.9
0.8
VIN = 5V
IOUT = 1A
0.7
0
0
0.2
0.4
0.6
0.8
I OUT (A)
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1
-50
-25
0
25
50
75
100
125
Temperature (°C)
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DS2517B-01 March 2015
RT2517B
Line Transient Response
Load Transient Response
VOUT
(10mV/Div)
VIN
(1V/Div)
IOUT
(1A/Div)
VOUT
(10mV/Div)
VIN = 3.3V to 4.3V, VOUT = 1.8V, IOUT = 1A
VIN = 3.3V, VOUT = 1.8V, IOUT = 0 to 1A
Time (100μs/Div)
Time (500μs/Div)
Power On from EN
Power Off from EN
VEN
(2V/Div)
VEN
(2V/Div)
VOUT
(1V/Div)
VOUT
(1V/Div)
I IN
(1A/Div)
I IN
(1A/Div)
VIN = 2.5V, VOUT = 1.5V, IOUT = 1A
VIN = 2.5V, VOUT = 1.5V, IOUT = 1A
Time (100μs/Div)
Time (100μs/Div)
PSRR vs. Frequency
0
-10
IOUT = 300mA
PSRR (dB)
-20
-30
IOUT = 100mA
-40
IOUT = 1mA
-50
-60
-70
VIN = 3.25V to 3.35V, VOUT = 1.8V
-80
100
1000
10000
100000
1000000
Frequency (Hz)
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RT2517B
Application Information
The RT2517B is a low voltage, low dropout linear regulator
with an external bias supply input capable of supporting
an input voltage range from 2.2V to 6V with a fixed output
voltage from 1V to 2V in 0.1V increments.
Output Voltage Setting
The RT2517B output voltage is adjustable from 2.2V to
6V via the external resistive voltage divider. The voltage
divider resistors can have values of 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  VADJ   1 R1 
 R2 
where VADJ is the reference voltage with a typical value of
1.2V.
Chip Enable Operation
The RT2517B goes into sleep mode when the EN pin is in
a logic low condition. In this condition, the pass transistor,
error amplifier, and band gap are all turned off, reducing
the supply current to only 10μA (max.). The EN pin can
be directly tied to VIN to keep the part on.
CIN and COUT Selection
Like any low dropout regulator, the external capacitors of
the RT2517B 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.
The RT2517B is designed specifically to work with low
ESR ceramic output capacitor for space saving and
performance consideration. Using a ceramic capacitor with
capacitance of at least 10μF and ESR larger than 1mΩ on
the RT2517B output ensures stability. Nevertheless, the
RT2517B 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 RT2517B.
UVLO Protection
Region of Stable COUT ESR vs. Load Current
100
Unstable Range
10
COUT ESR (Ω)
The RT2517B provides an input Under Voltage Lockout
protection (UVLO). When the input voltage exceeds the
UVLO rising threshold voltage (1.2V typ.), the device
resets the internal circuit and prepares for operation. If
the input voltage falls below the UVLO falling threshold
voltage during normal operation, the device will be shut
down. A hysteresis (140mV typ.) between the UVLO rising
and falling threshold voltage is designed to avoid noise.
1
Stable Range
0.1
0.01
Current Limit
The RT2517Bcontains an independent current limit
circuitry, which controls the pass transistor's gate voltage,
limiting the output current to 1A (typ.).
VIN = 3.3V, VOUT = 2.5V, COUT = 10μF / X7R
0.001
0.0
0.3
0.5
0.8
1.0
Load Current (A)
Figure 2
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RT2517B
Thermal Considerations
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.
2.4
Maximum Power Dissipation (W)1
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 :
Four-Layer PCB
2.0
1.6
1.2
0.8
0.4
0.0
0
For recommended operating condition specifications, the
maximum junction temperature is 125°C. The junction to
ambient thermal resistance, θJA, is layout dependent. For
SOP-8 (Exposed Pad) package, the thermal resistance,
θJA, is 49°C/W on a standard JEDEC 51-7 four-layer
25
50
75
100
125
Ambient Temperature (°C)
Figure 3. Derating Curve of Maximum Power Dissipation
thermal test board. The maximum power dissipation at TA
= 25°C can be calculated by the following formula :
PD(MAX) = (125°C − 25°C) / (49°C/W) = 2.041W for
SOP-8 (Exposed Pad) package
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.
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RT2517B
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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DS2517B-01 March 2015