FEATURES
Wide input voltage range: 3.6 V to 30 V
Adjustable and fixed (3.3 V, 5 V) output options
Integrated 1 A power switch
Uses small surface-mount components
Cycle-by-cycle current limiting
Peak input voltage (100 ms): 60 V
Configurable as a buck, buck-boost, and SEPIC
regulator
Available in 8-lead SOIC package
Supported by ADIsimPower™ design tool
FUNCTIONAL BLOCK DIAGRAM
SD
6
GND
7
BIAS
IN
3
8
FREQUENCY
AND CURRENT LIMIT
FOLDBACK
Industrial power systems
PC peripheral power systems
Preregulator for linear regulators
Distributed power systems
Automotive systems
Battery chargers
FB
CURRENT
LIMIT
200kHz
OSCILLATOR
+
APPLICATIONS
CURRENT SENSE
AMPLIFIER
2.50V
REGULATOR
4
2
BOOST
1
SWITCH
CMP
S
Q
DRIVER
R
1.2V
gm
ADP3050
00125-001
Data Sheet
200 kHz, 1 A High Voltage
Step-Down Switching Regulator
ADP3050
5
COMP
Figure 1.
GENERAL DESCRIPTION
The ADP3050 is a current mode monolithic buck (step down)
PWM switching regulator that contains a high current 1 A power
switch and all control, logic, and protection functions. It uses a
unique compensation scheme allowing the use of any type of
output capacitor (tantalum, ceramic, electrolytic, OS-CON).
Unlike some buck regulators, the design is not restricted to using
a specific type of output capacitor or ESR value.
A special boosted drive stage is used to saturate the NPN power
switch, providing a system efficiency higher than conventional
bipolar buck switchers. Further efficiency improvements are
obtained by using the low voltage regulated output to provide
the internal operating current of the device. A high switching
frequency allows the use of small external surface-mount components. A wide variety of standard off-the-shelf devices can be
used, providing a great deal of design flexibility. A complete
regulator design requires only a few external components.
The ADP3050 includes a shutdown input that places the device
in a low power mode, reducing the total supply current to under
20 µA. Internal protection features include thermal shutdown
circuitry and a cycle-by-cycle current limit for the power switch
to provide complete device protection under fault conditions.
The ADP3050 provides excellent line and load regulation,
maintaining typically less than ±3% output voltage accuracy
over temperature and under all input voltage and output
current conditions.
The ADP3050 is specified over the industrial temperature range
of −40°C to +85°C and is available in a thermally enhanced 8-lead
(not Pb-free only) SOIC package and a standard 8-lead (Pb-free
only) RoHS-compliant SOIC package.
Rev. C
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2008–2012 Analog Devices, Inc. All rights reserved.
ADP3050
Data Sheet
TABLE OF CONTENTS
Features .............................................................................................. 1
Catch Diode Selection ............................................................... 13
Applications ....................................................................................... 1
Input Capacitor Selection .......................................................... 14
Functional Block Diagram .............................................................. 1
Discontinous Mode Ringing ..................................................... 14
General Description ......................................................................... 1
Setting the Output Voltage ........................................................ 14
Revision History ............................................................................... 2
Frequency Compensation ......................................................... 14
Specifications..................................................................................... 3
Current Limit/Frequency Foldback ......................................... 15
Absolute Maximum Ratings............................................................ 4
Bias Pin Connection .................................................................. 15
ESD Caution .................................................................................. 4
Boosted Drive Stage ................................................................... 15
Pin Configuration and Function Descriptions ............................. 5
Start-Up/Minimum Input Voltage ........................................... 15
Typical Performance Characteristics ............................................. 6
Thermal Considerations............................................................ 16
Theory of Operation ...................................................................... 10
Board Layout Guidelines ............................................................... 17
Setting the Output Voltage ........................................................ 10
Typical Applications ................................................................... 17
Applications Information .............................................................. 11
Inverting (Buck Boost) Regulator ............................................ 18
ADIsimPower Design Tool ....................................................... 11
Outline Dimensions ....................................................................... 20
Inductor Selection ...................................................................... 11
Ordering Guide .......................................................................... 20
Output Capacitor Selection ....................................................... 12
REVISION HISTORY
6/12—Rev. B to Rev. C
Change to Features Section ............................................................. 1
Added ADIsimPower Design Tool Section ................................. 11
Changes to Ordering Guide .......................................................... 20
3/08—Rev. A to Rev. B
Updated Format .................................................................. Universal
Changes to General Description Section ...................................... 1
Changes to Figure 3 and Figure 5 ................................................... 6
Changes to Table 2 ............................................................................ 4
Deleted Table 4 ................................................................................ 14
Changes to Table 5 .......................................................................... 15
Deleted Table 8 ................................................................................ 15
Deleted Table 7 ................................................................................ 16
Deleted Table 9 ................................................................................ 16
Changes to Boosted Drive Stage Section and Thermal
Considerations Sections................................................................. 19
Changes to Figure 27 ...................................................................... 20
Changes to Ordering Guide .......................................................... 23
Rev. C | Page 2 of 20
Data Sheet
ADP3050
SPECIFICATIONS
VIN = 10 V, TA = −40°C to +85°C, unless otherwise noted.
Table 1.
Parameter 1
FEEDBACK
Feedback Voltage
ADP3050
ADP3050-3.3
ADP3050-5
Line Regulation
Load Regulation
Symbol
Conditions
VFB
Over line and temperature
Input Bias Current
ERROR AMPLIFIER
Transconductance 2
Voltage Gain2
Output Current
ADP3050
ADP3050-3.3
ADP3050-5
OSCILLATOR
Oscillator Frequency 3
Minimum Duty Cycle
Maximum Duty Cycle
SWITCH
Average Output Current Limit 4
ADP3050
ADP3050-3.3
ADP3050-5
Peak Switch Current Limit 5
Saturation Voltage
Leakage Current
SHUTDOWN
Input Voltage Low
Input Voltage High
SUPPLY
Input Voltage Range 6
Minimum BIAS Voltage
Minimum BOOST Voltage
IN Supply Current
Normal Mode
Shutdown Mode
BIAS Supply Current
BOOST Supply Current
IFB
VIN = 10 V to 30 V, no load
ILOAD = 100 mA to 1 A, ADP3050AR only
ADP3050AR-3.3, ADP3050AR-5
ADP3050AR only
Min
Typ
Max
Unit
1.16
3.20
4.85
1.20
3.30
5.00
0.005
+0.1
+0.1
0.65
1.24
3.40
5.15
V
V
V
%/V
%/A
%/A
μA
−1.0
−0.5
gm
AVOL
COMP = 1.0 V, FB = 1.1 V to 1.3 V
COMP = 1.0 V, FB = 3.0 V to 3.6 V
COMP = 1.0 V, FB = 4.5 V to 5.5 V
fOSC
DMIN
DMAX
+1.0
+0.5
2
1250
300
μMho
V/V
±115
±120
±135
μA
μA
μA
170
200
10
90
240
kHz
%
%
1.0
1.0
1.0
1.5
1.25
1.25
1.25
1.7
0.65
50
1.5
1.5
1.5
2.1
0.95
A
A
A
A
V
nA
0.4
V
V
30
3.0
3.0
V
V
V
1.5
40
6.0
mA
μA
mA
mA
mA
ICL(AVG)
BOOST = 15 V, FB = 1.1 V
BOOST = 15 V, FB = 3.0 V
BOOST = 15 V, FB = 4.5 V
ICL(PEAK)
BOOST = 15 V, ILOAD = 1 A
2.0
VIN
VBIAS
VBOOST
IQ
IBIAS
IBOOST
3.6
BIAS = 5.0 V
SD = 0 V, VIN ≤ 30 V
BIAS = 5.0 V
BOOST = 15 V, ISW = 0.5 A
BOOST = 15 V, ISW = 1.0 A
0.7
15
4.0
18
20
40
All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC).
Transconductance and voltage gain measurements refer to the internal amplifier without the voltage divider. To calculate the transconductance and gain of the fixed
voltage parts, divide the values shown by FB/1.20.
3
The switching frequency is reduced when the feedback pin is lower than 0.8 × FB.
4
See Figure 24 for typical application circuit.
5
Switch current limit is measured with no diode, no inductor, and no output capacitor.
6
Minimum input voltage is not measured directly, but is guaranteed by other tests. The actual minimum input voltage needed to keep the output in regulation
depends on output voltage and load current.
1
2
Rev. C | Page 3 of 20
ADP3050
Data Sheet
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
IN Voltage
Continuous
Peak (
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