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稳压IC lm2596数据手册.pdf
LM2596
General Description
Features
Applications
Typical Application
Connection Diagrams and Ordering Information
Absolute Maximum Ratings
Operating Conditions
LM2596-3.3 Electrical Characteristics
LM2596-5.0 Electrical Characteristics
LM2596-12 Electrical Characteristics
LM2596-ADJ Electrical Characteristics
All Output Voltage Versions Electrical Characteristics
Typical Performance Characteristics
Typical Performance Characteristics
Test Circuit and Layout Guidelines
FIGURE 1. Standard Test Circuits and Layout Guides
LM2596 Series Buck Regulator Design Procedure (Fixed Output)
FIGURE 2. LM2596 Fixed Voltage Quick Design Component Selection Table
LM2596 Series Buck Regulator Design Procedure (Adjustable Output)
LM2596 Series Buck Regulator Design Procedure (Adjustable Output)
FIGURE 3. Output Capacitor and Feedforward Capacitor Selection Table
LM2596 Series Buck Regulator Design Procedure
INDUCTOR VALUE SELECTION GUIDES
FIGURE 4. LM2596-3.3
FIGURE 5. LM2596-5.0
FIGURE 6. LM2596-12
FIGURE 7. LM2596-ADJ
FIGURE 8. Inductor Manufacturers Part Numbers
FIGURE 9. Inductor Manufacturers Phone Numbers
FIGURE 10. Capacitor Manufacturers Phone Numbers
FIGURE 11. Diode Selection Table
FIGURE 12.
Application Information
PIN FUNCTIONS
EXTERNAL COMPONENTS
FEEDFORWARD CAPACITOR (Adjustable Output Voltage Version)
FIGURE 13. RMS Current Ratings for Low ESR Electrolytic Capacitors (Typical)
OUTPUT CAPACITOR
FIGURE 14. Capacitor ESR vs Capacitor Voltage Rating (Typical Low ESR Electrolytic Capacitor)
CATCH DIODE
FIGURE 15. Capacitor ESR Change vs Temperature
INDUCTOR SELECTION
FIGURE 16. (IIND) Peak-to-Peak Inductor Ripple Current (as a Percentage of the Load Current) vs
DISCONTINUOUS MODE OPERATION
FIGURE 17. Post Ripple Filter Waveform
OUTPUT VOLTAGE RIPPLE AND TRANSIENTS
FIGURE 18. Peak-to-Peak Inductor Ripple Current vs Load Current
OPEN CORE INDUCTORS
THERMAL CONSIDERATIONS
FIGURE 19. Junction Temperature Rise, TO-220
FIGURE 20. Junction Temperature Rise, TO-263
FIGURE 21. Delayed Startup
FIGURE 22. Undervoltage Lockout for Buck Regulator
DELAYED STARTUP
UNDERVOLTAGE LOCKOUT
INVERTING REGULATOR
FIGURE 23. Undervoltage Lockout for Inverting Regulator
FIGURE 24. Undervoltage Lockout with Hysteresis for Inverting Regulator
FIGURE 25. Inverting -5V Regulator with Delayed Startup
FIGURE 26. Inverting Regulator Typical Load Current
INVERTING REGULATOR SHUTDOWN METHODS
FIGURE 27. Inverting Regulator Ground Referenced Shutdown
FIGURE 28. Inverting Regulator Ground Referenced Shutdown using Opto Device
TYPICAL THROUGH HOLE PC BOARD LAYOUT, FIXED OUTPUT (1X SIZE), DOUBLE SIDED
TYPICAL THROUGH HOLE PC BOARD LAYOUT, ADJUSTABLE OUTPUT (1X SIZE), DOUBLE SIDED
FIGURE 29. PC Board Layout
Physical Dimensions
LM2596
LM2596 SIMPLE SWITCHER Power Converter 150 kHz3A Step-Down Voltage
Regulator
Literature Number: SNVS124B
May 2002
Features
n 3.3V, 5V, 12V, and adjustable output versions
n Adjustable version output voltage range, 1.2V to 37V
±4% max over line and load conditions
LM2596
SIMPLE SWITCHER® Power Converter 150 kHz
3A Step-Down Voltage Regulator
General Description
The LM2596 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 3A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, and an adjust-
able output version.
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation†, and a fixed-frequency oscillator.
The LM2596 series operates at a switching frequency of
150 kHz thus allowing smaller sized filter components than
what would be needed with lower frequency switching regu-
lators. Available in a standard 5-lead TO-220 package with
several different lead bend options, and a 5-lead TO-263
surface mount package.
A standard series of inductors are available from several
different manufacturers optimized for use with the LM2596
series. This feature greatly simplifies the design of
switch-mode power supplies.
Other features include a guaranteed ±4% tolerance on out-
put voltage under specified input voltage and output load
conditions, and ±15% on the oscillator frequency. External
shutdown is included, featuring typically 80 µA standby cur-
rent. Self protection features include a two stage frequency
reducing current
for the output switch and an over
temperature shutdown for complete protection under fault
conditions.
n Available in TO-220 and TO-263 packages
n Guaranteed 3A output load current
n Input voltage range up to 40V
n Requires only 4 external components
n Excellent line and load regulation specifications
n 150 kHz fixed frequency internal oscillator
n TTL shutdown capability
n Low power standby mode, IQ typically 80 µA
n High efficiency
n Uses readily available standard inductors
n Thermal shutdown and current limit protection
Applications
n Simple high-efficiency step-down (buck) regulator
n On-card switching regulators
n Positive to negative converter
Note: †Patent Number 5,382,918.
limit
Typical Application (Fixed Output Voltage
Versions)
01258301
SIMPLE SWITCHER® and SwitchersMadeSimple® are registered trademarks of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
DS012583
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Connection Diagrams and Ordering Information
Bent and Staggered Leads, Through Hole
Package
5-Lead TO-220 (T)
Surface Mount Package
5-Lead TO-263 (S)
Order Number LM2596T-3.3, LM2596T-5.0,
LM2596T-12 or LM2596T-ADJ
See NS Package Number T05D
01258302
Order Number LM2596S-3.3, LM2596S-5.0,
LM2596S-12 or LM2596S-ADJ
See NS Package Number TS5B
01258303
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Maximum Supply Voltage
ON /OFF Pin Input Voltage
Feedback Pin Voltage
Output Voltage to Ground
(Steady State)
Power Dissipation
Storage Temperature Range
ESD Susceptibility
45V
−0.3 £ V £ +25V
−0.3 £ V £ +25V
−1V
Internally limited
−65˚C to +150˚C
Human Body Model (Note 2)
2 kV
Lead Temperature
S Package
Vapor Phase (60 sec.)
Infrared (10 sec.)
T Package (Soldering, 10 sec.)
Maximum Junction Temperature
+215˚C
+245˚C
+260˚C
+150˚C
Operating Conditions
Temperature Range
Supply Voltage
−40˚C £ TJ £ +125˚C
4.5V to 40V
LM2596-3.3
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range
Symbol
Parameter
Conditions
SYSTEM PARAMETERS (Note 5) Test Circuit Figure1
VOUT
4.75V £ VIN £ 40V, 0.2A £
Output Voltage
ILOAD £ 3A
Efficiency
VIN = 12V, ILOAD = 3A
LM2596-3.3
Typ
(Note 3)
Limit
(Note 4)
3.3
73
3.168/3.135
3.432/3.465
Units
(Limits)
V
V(min)
V(max)
%
LM2596-5.0
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range
Symbol
Parameter
Conditions
SYSTEM PARAMETERS (Note 5) Test Circuit Figure1
7V £ VIN £ 40V, 0.2A £
VOUT
Output Voltage
ILOAD £ 3A
Efficiency
VIN = 12V, ILOAD = 3A
LM2596-5.0
Typ
(Note 3)
Limit
(Note 4)
5.0
80
4.800/4.750
5.200/5.250
Units
(Limits)
V
V(min)
V(max)
%
LM2596-12
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range
Symbol
Parameter
Conditions
SYSTEM PARAMETERS (Note 5) Test Circuit Figure1
VOUT
15V £ VIN £ 40V, 0.2A £
Output Voltage
ILOAD £ 3A
Efficiency
VIN = 25V, ILOAD = 3A
LM2596-12
Typ
(Note 3)
Limit
(Note 4)
12.0
90
11.52/11.40
12.48/12.60
Units
(Limits)
V
V(min)
V(max)
%
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LM2596-ADJ
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range
Symbol
Parameter
Conditions
SYSTEM PARAMETERS (Note 5) Test Circuit Figure1
VFB
Feedback Voltage
4.5V £ VIN £ 40V, 0.2A £
VOUT programmed for 3V. Circuit of Figure1
ILOAD £ 3A
LM2596-ADJ
Typ
(Note 3)
1.230
Limit
(Note 4)
1.193/1.180
1.267/1.280
Efficiency
VIN = 12V, VOUT = 3V, ILOAD = 3A
73
Units
(Limits)
V
V(min)
V(max)
%
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V ver-
sion. ILOAD = 500 mA
LM2596-XX
Typ
Limit
(Note 3)
(Note 4)
Symbol
Parameter
Conditions
DEVICE PARAMETERS
Ib
Feedback Bias Current
Adjustable Version Only, VFB = 1.3V
fO
Oscillator Frequency
(Note 6)
VSAT
Saturation Voltage
IOUT = 3A (Notes 7, 8)
DC
ICL
IL
IQ
Max Duty Cycle (ON)
Min Duty Cycle (OFF)
Current Limit
(Note 8)
(Note 9)
Peak Current (Notes 7, 8)
Output Leakage Current
Output = 0V (Notes 7, 9)
Output = −1V (Note 10)
Quiescent Current
(Note 9)
ISTBY
Standby Quiescent Current ON/OFF pin = 5V (OFF)
(Note 10)
Thermal Resistance
q JC
q JA
q JA
q JA
q JA
ON/OFF CONTROL Test Circuit Figure1
TO-220 or TO-263 Package, Junction to Case
TO-220 Package, Junction to Ambient (Note 11)
TO-263 Package, Junction to Ambient (Note 12)
TO-263 Package, Junction to Ambient (Note 13)
TO-263 Package, Junction to Ambient (Note 14)
ON /OFF Pin Logic Input
Threshold Voltage
VIH
VIL
Low (Regulator ON)
High (Regulator OFF)
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1.16
100
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4.5
2
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80
2
50
50
30
20
1.3
Units
(Limits)
nA
50/100
nA (max)
127/110
173/173
kHz
kHz(min)
kHz(max)
V
1.4/1.5
V(max)
%
A
A(min)
A(max)
µA(max)
mA
mA(max)
mA
mA(max)
µA
3.6/3.4
6.9/7.5
50
30
10
200/250
µA(max)
˚C/W
˚C/W
˚C/W
˚C/W
˚C/W
V
V(max)
V(min)
0.6
2.0
h
All Output Voltage Versions
Electrical Characteristics (Continued)
Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera-
ture Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V ver-
sion. ILOAD = 500 mA
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Symbol
Parameter
Conditions
IH
IL
ON /OFF Pin Input Current VLOGIC = 2.5V (Regulator OFF)
VLOGIC = 0.5V (Regulator ON)
LM2596-XX
Typ
Limit
(Note 3)
(Note 4)
5
0.02
15
5
Units
(Limits)
µA
µA(max)
µA
µA(max)
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.
Note 2: The human body model is a 100 pF capacitor discharged through a 1.5k resistor into each pin.
Note 3: Typical numbers are at 25˚C and represent the most likely norm.
Note 4: All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100%
production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to
calculate Average Outgoing Quality Level (AOQL).
Note 5: External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator
system performance. When the LM2596 is used as shown in the Figure1test circuit, system performance will be as shown in system parameters section of Electrical
Characteristics.
Note 6: The switching frequency is reduced when the second stage current limit is activated.
Note 7: No diode, inductor or capacitor connected to output pin.
Note 8: Feedback pin removed from output and connected to 0V to force the output transistor switch ON.
Note 9: Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version, and 15V for the 12V version, to force the output transistor
switch OFF.
Note 10: VIN = 40V.
Note 11: Junction to ambient thermal resistance (no external heat sink) for the TO-220 package mounted vertically, with the leads soldered to a printed circuit board
with (1 oz.) copper area of approximately 1 in2.
Note 12: Junction to ambient thermal resistance with the TO-263 package tab soldered to a single printed circuit board with 0.5 in2 of (1 oz.) copper area.
Note 13: Junction to ambient thermal resistance with the TO-263 package tab soldered to a single sided printed circuit board with 2.5 in2 of (1 oz.) copper area.
Note 14: Junction to ambient thermal resistance with the TO-263 package tab soldered to a double sided printed circuit board with 3 in2 of (1 oz.) copper area on
the LM2596S side of the board, and approximately 16 in2 of copper on the other side of the p-c board. See Application Information in this data sheet and the thermal
model in Switchers Made Simple™ version 4.3 software.
Typical Performance Characteristics (Circuit of Figure 1)
Normalized
Output Voltage
Line Regulation
Efficiency
01258304
01258305
01258306
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Typical Performance Characteristics (Circuit of Figure 1) (Continued)
Switch Saturation
Voltage
Switch Current Limit
Dropout Voltage
01258307
01258308
01258309
Operating
Quiescent Current
Shutdown
Quiescent Current
Minimum Operating
Supply Voltage
01258310
01258311
01258312
ON /OFF Threshold
Voltage
ON /OFF Pin
Current (Sinking)
Switching Frequency
01258313
01258314
01258315
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Typical Performance Characteristics (Circuit of Figure 1) (Continued)
Feedback Pin
Bias Current
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