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May 2002
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 available in fixed output voltages of 3.3V, 5V, 12V, and an adjustable output version.
Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation², 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 regulators. 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 output voltage under specified input voltage and output load conditions, and ±15% on the oscillator frequency. External shutdown is included, featuring typically 80 µA standby current. Self protection features include a two stage frequency reducing current limit for the output switch and an over temperature shutdown for complete protection under fault conditions.
Features
n3.3V, 5V, 12V, and adjustable output versions
nAdjustable version output voltage range, 1.2V to 37V
±4% max over line and load conditions
nAvailable in TO-220 and TO-263 packages
nGuaranteed 3A output load current
nInput voltage range up to 40V
nRequires only 4 external components
nExcellent line and load regulation specifications
n150 kHz fixed frequency internal oscillator
nTTL shutdown capability
nLow power standby mode, IQ typically 80 µA
nHigh efficiency
nUses readily available standard inductors
nThermal shutdown and current limit protection
Applications
nSimple high-efficiency step-down (buck) regulator
nOn-card switching regulators
nPositive to negative converter
Note: ²Patent Number 5,382,918.
Typical Application (Fixed Output Voltage
Versions)
01258301
SIMPLE SWITCHER® and Switchers Made Simple® are registered trademarks of National Semiconductor Corporation.
Regulator Voltage Down-Step 3A kHz 150 Converter Power SWITCHER SIMPLE LM2596
© 2002 National Semiconductor Corporation |
DS012583 |
www.national.com |
LM2596
Connection Diagrams and Ordering Information
Bent and Staggered Leads, Through Hole |
|
Package |
Surface Mount Package |
5-Lead TO-220 (T) |
5-Lead TO-263 (S) |
01258302 |
01258303 |
|
Order Number LM2596S-3.3, LM2596S-5.0, |
||
Order Number LM2596T-3.3, LM2596T-5.0, |
||
LM2596T-12 or LM2596T-ADJ |
LM2596S-12 or LM2596S-ADJ |
|
See NS Package Number T05D |
See NS Package Number TS5B |
www.national.com |
2 |
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 |
45V |
||
−0.3 |
≤ V ≤ +25V |
||
ON |
/OFF Pin Input Voltage |
||
Feedback Pin Voltage |
−0.3 |
≤ V ≤+25V |
|
Output Voltage to Ground |
|||
(Steady State) |
−1V |
||
Power Dissipation |
Internally limited |
||
Storage Temperature Range |
−65ÊC to +150ÊC |
||
ESD Susceptibility |
|||
Human Body Model (Note 2) |
2 kV |
Lead Temperature |
|
S Package |
|
Vapor Phase (60 sec.) |
+215ÊC |
Infrared (10 sec.) |
+245ÊC |
T Package (Soldering, 10 sec.) |
+260ÊC |
Maximum Junction Temperature |
+150ÊC |
Operating Conditions
Temperature Range |
−40ÊC ≤ TJ ≤ +125ÊC |
Supply Voltage |
4.5V to 40V |
LM2596-3.3
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range
LM2596-3.3 |
Units |
|||||
Symbol |
Parameter |
Conditions |
||||
Typ |
Limit |
|||||
(Limits) |
||||||
(Note 3) |
(Note 4) |
|||||
SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 |
||||||
VOUT |
Output Voltage |
4.75V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A |
3.3 |
V |
||
3.168/3.135 |
V(min) |
|||||
3.432/3.465 |
V(max) |
|||||
η |
Efficiency |
VIN = 12V, ILOAD = 3A |
73 |
% |
||
LM2596-5.0
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range
LM2596-5.0 |
Units |
|||||
Symbol |
Parameter |
Conditions |
||||
Typ |
Limit |
|||||
(Limits) |
||||||
(Note 3) |
(Note 4) |
|||||
SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 |
||||||
VOUT |
Output Voltage |
7V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A |
5.0 |
V |
||
4.800/4.750 |
V(min) |
|||||
5.200/5.250 |
V(max) |
|||||
η |
Efficiency |
VIN = 12V, ILOAD = 3A |
80 |
% |
||
LM2596-12
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range
LM2596-12 |
Units |
|||||
Symbol |
Parameter |
Conditions |
||||
Typ |
Limit |
|||||
(Limits) |
||||||
(Note 3) |
(Note 4) |
|||||
SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 |
||||||
VOUT |
Output Voltage |
15V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A |
12.0 |
V |
||
11.52/11.40 |
V(min) |
|||||
12.48/12.60 |
V(max) |
|||||
η |
Efficiency |
VIN = 25V, ILOAD = 3A |
90 |
% |
||
LM2596
3 |
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LM2596
LM2596-ADJ
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range
LM2596-ADJ |
Units |
|||||
Symbol |
Parameter |
Conditions |
||||
Typ |
Limit |
|||||
(Limits) |
||||||
(Note 3) |
(Note 4) |
|||||
SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 |
||||||
VFB |
Feedback Voltage |
4.5V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A |
1.230 |
V |
||
VOUT programmed for 3V. Circuit of Figure 1 |
1.193/1.180 |
V(min) |
||||
1.267/1.280 |
V(max) |
|||||
η |
Efficiency |
VIN = 12V, VOUT = 3V, ILOAD = 3A |
73 |
% |
||
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V version. ILOAD = 500 mA
LM2596-XX |
Units |
||||||||
Symbol |
Parameter |
Conditions |
|||||||
Typ |
Limit |
||||||||
(Limits) |
|||||||||
(Note 3) |
(Note 4) |
||||||||
DEVICE PARAMETERS |
|||||||||
Ib |
Feedback Bias Current |
Adjustable Version Only, VFB = 1.3V |
10 |
nA |
|||||
50/100 |
nA (max) |
||||||||
fO |
Oscillator Frequency |
(Note 6) |
150 |
kHz |
|||||
127/110 |
kHz(min) |
||||||||
173/173 |
kHz(max) |
||||||||
VSAT |
Saturation Voltage |
IOUT = 3A (Notes 7, 8) |
1.16 |
V |
|||||
1.4/1.5 |
V(max) |
||||||||
DC |
Max Duty Cycle (ON) |
(Note 8) |
100 |
% |
|||||
Min Duty Cycle (OFF) |
(Note 9) |
0 |
|||||||
ICL |
Current Limit |
Peak Current (Notes 7, 8) |
4.5 |
A |
|||||
3.6/3.4 |
A(min) |
||||||||
6.9/7.5 |
A(max) |
||||||||
IL |
Output Leakage Current |
Output = 0V (Notes 7, 9) |
50 |
µA(max) |
|||||
Output = −1V (Note 10) |
2 |
mA |
|||||||
30 |
mA(max) |
||||||||
IQ |
Quiescent Current |
(Note 9) |
5 |
mA |
|||||
10 |
mA(max) |
||||||||
ISTBY |
Standby Quiescent Current |
ON/OFF pin = 5V (OFF) |
(Note 10) |
80 |
µA |
||||
200/250 |
µA(max) |
||||||||
θJC |
Thermal Resistance |
TO-220 or TO-263 Package, Junction to Case |
2 |
ÊC/W |
|||||
θJA |
TO-220 Package, Junction to Ambient (Note 11) |
50 |
ÊC/W |
||||||
θJA |
TO-263 Package, Junction to Ambient (Note 12) |
50 |
ÊC/W |
||||||
θJA |
TO-263 Package, Junction to Ambient (Note 13) |
30 |
ÊC/W |
||||||
θJA |
TO-263 Package, Junction to Ambient (Note 14) |
20 |
ÊC/W |
||||||
ON/OFF CONTROL Test Circuit Figure 1 |
|||||||||
ON |
/OFF Pin Logic Input |
1.3 |
V |
||||||
VIH |
Threshold Voltage |
Low (Regulator ON) |
0.6 |
V(max) |
|||||
VIL |
High (Regulator OFF) |
2.0 |
V(min) |
||||||
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4 |
All Output Voltage Versions Electrical Characteristics (Continued)
Specifications with standard type face are for TJ = 25ÊC, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V version. ILOAD = 500 mA
LM2596-XX |
Units |
|||||||
Symbol |
Parameter |
Conditions |
||||||
Typ |
Limit |
|||||||
(Limits) |
||||||||
(Note 3) |
(Note 4) |
|||||||
IH |
VLOGIC = 2.5V |
(Regulator OFF) |
5 |
µA |
||||
ON |
/OFF Pin Input Current |
|||||||
15 |
µA(max) |
|||||||
IL |
VLOGIC = 0.5V |
(Regulator ON) |
0.02 |
µA |
||||
5 |
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 25ÊC 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 Figure 1 test 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 |
LM2596
5 |
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LM2596
Typical Performance Characteristics (Circuit of Figure 1) (Continued)
Switch Saturation |
||
Voltage |
Switch Current Limit |
Dropout Voltage |
01258307 |
01258308 |
01258309 |
Operating |
Shutdown |
Minimum Operating |
Quiescent Current |
Quiescent Current |
Supply Voltage |
01258310 01258311 01258312
ON /OFF Threshold |
ON /OFF Pin |
||||
Voltage |
Current (Sinking) |
Switching Frequency |
|||
01258313 |
01258314 |
01258315 |
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6 |
Typical Performance Characteristics (Circuit of Figure 1) (Continued)
Feedback Pin
Bias Current
01258316
LM2596
7 |
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LM2596
Typical Performance Characteristics
Continuous Mode Switching Waveforms |
Discontinuous Mode Switching Waveforms |
VIN = 20V, VOUT = 5V, ILOAD = 2A |
VIN = 20V, VOUT = 5V, ILOAD = 500 mA |
L = 32 µH, C OUT = 220 µF, C OUT ESR = 50 mΩ |
L = 10 µH, C OUT = 330 µF, C OUT ESR = 45 mΩ |
01258317 |
01258318 |
|
Horizontal Time Base: 2 µs/div. |
||
Horizontal Time Base: 2 µs/div. |
||
A: Output Pin Voltage, 10V/div. |
A: Output Pin Voltage, 10V/div. |
|
B: Inductor Current 1A/div. |
B: Inductor Current 0.5A/div. |
|
C: Output Ripple Voltage, 50 mV/div. |
C: Output Ripple Voltage, 100 mV/div. |
|
Load Transient Response for Continuous Mode |
Load Transient Response for Discontinuous Mode |
|
VIN = 20V, VOUT = 5V, ILOAD = 500 mA to 2A |
VIN = 20V, VOUT = 5V, ILOAD = 500 mA to 2A |
|
L = 32 µH, C OUT = 220 µF, C OUT ESR = 50 mΩ |
L = 10 µH, C OUT = 330 µF, C OUT ESR = 45 mΩ |
01258320
Horizontal Time Base: 200 µs/div.
01258319
Horizontal Time Base: 100 µs/div. |
A: Output Voltage, 100 mV/div. (AC) |
|
B: 500 mA to 2A Load Pulse |
||
A: Output Voltage, 100 mV/div. (AC) |
||
B: 500 mA to 2A Load Pulse |
Test Circuit and Layout Guidelines
Fixed Output Voltage Versions
01258322
CIN |
Ð 470 µF, 50V, Aluminum Electrolytic Nichicon ªPL Seriesº |
COUT Ð 220 µF, 25V Aluminum Electrolytic, Nichicon ªPL Seriesº |
|
D1 |
Ð 5A, 40V Schottky Rectifier, 1N5825 |
L1 |
Ð 68 µH, L38 |
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8 |