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LM2576/LM2576HV Series SIMPLE SWITCHER 3A Step-Down Voltage Regulator
August 2004
LM2576/LM2576HV Series
SIMPLE SWITCHER
®
3A Step-Down Voltage Regulator
General Description
The LM2576 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving 3A load with
excellent line and load regulation. These devices are avail-
able in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable 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 LM2576 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially re-
duces the size of the heat sink, and in some cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2576 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power supplies.
Other features include a guaranteed
±
4% tolerance on out-
put voltage within specified input voltages and output load
conditions, and
±
10% on the oscillator frequency. External
shutdown is included, featuring 50 µA (typical) standby cur-
rent. The output switch includes cycle-by-cycle current limit-
ing, as well as thermal shutdown for full protection under
fault conditions.
Features
n
3.3V, 5V, 12V, 15V, and adjustable output versions
n
Adjustable version output voltage range,
1.23V to 37V (57V for HV version)
±
4% max over
line and load conditions
n
Guaranteed 3A output current
n
Wide input voltage range, 40V up to 60V for
HV version
n
Requires only 4 external components
n
52 kHz fixed frequency internal oscillator
n
TTL shutdown capability, low power standby mode
n
High efficiency
n
Uses readily available standard inductors
n
Thermal shutdown and current limit protection
n
P+ Product Enhancement tested
Applications
n
n
n
n
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
Typical Application
Versions)
(Fixed Output Voltage
01147601
FIGURE 1.
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation
DS011476
www.national.com
LM2576/LM2576HV
Block Diagram
01147602
3.3V R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For ADJ. Version
R1 = Open, R2 = 0Ω
Patent Pending
Ordering Information
Temperature
Range
Output Voltage
3.3
5.0
LM2576HVS-5.0
LM2576S-5.0
LM2576SX-5.0
LM2576HVT-5.0
LM2576T-5.0
LM2576HVT-5.0
Flow LB03
LM2576T-5.0
Flow LB03
12
LM2576S-12
LM2576SX-12
LM2576T-12
Flow LB03
LM2576T-12
Flow LB03
15
LM2576S-15
LM2576SX-15
LM2576T-15
Flow LB03
LM2576T-15
Flow LB03
ADJ
LM2576S-ADJ
LM2576SX-ADJ
LM2576T-ADJ
T05D
Flow LB03
LM2576T-ADJ
Flow LB03
TS5B
Tape & Reel
T05A
TO-220
LM2576HVS-12 LM2576HVS-15 LM2576HVS-ADJ
NS Package Package
Type
Number
TS5B
TO-263
−40˚C
≤
T
A
LM2576HVS-3.3
≤
125˚C LM2576S-3.3
LM2576SX-3.3
LM2576HVT-3.3
LM2576T-3.3
LM2576HVT-3.3
Flow LB03
LM2576T-3.3
Flow LB03
LM2576HVSX-3.3 LM2576HVSX-5.0 LM2576HVSX-12 LM2576HVSX-15 LM2576HVSX-ADJ
LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ
LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ
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2
LM2576/LM2576HV
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
LM2576
LM2576HV
ON /OFF Pin Input Voltage
Output Voltage to Ground
(Steady State)
Power Dissipation
Storage Temperature Range
Maximum Junction Temperature
−1V
Internally Limited
−65˚C to +150˚C
150˚C
45V
63V
−0.3V
≤
V
≤
+V
IN
Minimum ESD Rating
(C = 100 pF, R = 1.5 kΩ)
Lead Temperature
(Soldering, 10 Seconds)
260˚C
2 kV
Operating Ratings
Temperature Range
LM2576/LM2576HV
Supply Voltage
LM2576
LM2576HV
40V
60V
−40˚C
≤
T
J
≤
+125˚C
LM2576-3.3, LM2576HV-3.3
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over full Operating Temperature
Range.
Symbol
Parameter
Conditions
Typ
SYSTEM PARAMETERS
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 12V, I
LOAD
= 0.5A
Circuit of
Figure 2
V
OUT
Output Voltage
LM2576
V
OUT
Output Voltage
LM2576HV
η
Efficiency
6V
≤
V
IN
≤
40V, 0.5A
≤
I
LOAD
≤
3A
Circuit of
Figure 2
6V
≤
V
IN
≤
60V, 0.5A
≤
I
LOAD
≤
3A
Circuit of
Figure 2
V
IN
= 12V, I
LOAD
= 3A
75
3.3
3.168/3.135
3.450/3.482
3.3
3.168/3.135
3.432/3.465
3.3
3.234
3.366
V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
V(Max)
%
LM2576-3.3
LM2576HV-3.3
Limit
(Note 2)
Units
(Limits)
LM2576-5.0, LM2576HV-5.0
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
Figure 2
boldface type
apply over full Operating Tem-
perature Range.
Symbol
Parameter
Conditions
Typ
SYSTEM PARAMETERS
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 12V, I
LOAD
= 0.5A
Circuit of
Figure 2
V
OUT
Output Voltage
LM2576
V
OUT
Output Voltage
LM2576HV
0.5A
≤
I
LOAD
≤
3A,
8V
≤
V
IN
≤
40V
Circuit of
Figure 2
0.5A
≤
I
LOAD
≤
3A,
8V
≤
V
IN
≤
60V
Circuit of
Figure 2
5.0
4.800/4.750
5.225/5.275
5.0
4.800/4.750
5.200/5.250
5.0
4.900
5.100
V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
V(Max)
LM2576-5.0
LM2576HV-5.0
Limit
(Note 2)
Units
(Limits)
3
www.national.com
LM2576/LM2576HV
LM2576-5.0, LM2576HV-5.0
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
= 25˚C, and those with
Figure 2
boldface type
apply over full Operating Tem-
perature Range.
Symbol
Parameter
Conditions
Typ
SYSTEM PARAMETERS
(Note 3)
Test Circuit
Figure 2
η
Efficiency
V
IN
= 12V, I
LOAD
= 3A
77
%
LM2576-5.0
LM2576HV-5.0
Limit
(Note 2)
Units
(Limits)
LM2576-12, LM2576HV-12
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over full Operating Temperature
Range.
Symbol
Parameter
Conditions
Typ
SYSTEM PARAMETERS
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 25V, I
LOAD
= 0.5A
Circuit of
Figure 2
V
OUT
Output Voltage
LM2576
V
OUT
Output Voltage
LM2576HV
η
Efficiency
0.5A
≤
I
LOAD
≤
3A,
15V
≤
V
IN
≤
40V
Circuit of
Figure 2
0.5A
≤
I
LOAD
≤
3A,
15V
≤
V
IN
≤
60V
Circuit of
Figure 2
V
IN
= 15V, I
LOAD
= 3A
88
12
11.52/11.40
12.54/12.66
12
11.52/11.40
12.48/12.60
12
11.76
12.24
V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
V(Max)
%
LM2576-12
LM2576HV-12
Limit
(Note 2)
Units
(Limits)
LM2576-15, LM2576HV-15
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over full Operating Temperature
Range.
Symbol
Parameter
Conditions
Typ
SYSTEM PARAMETERS
(Note 3)
Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 25V, I
LOAD
= 0.5A
Circuit of
Figure 2
V
OUT
Output Voltage
LM2576
V
OUT
Output Voltage
LM2576HV
η
Efficiency
0.5A
≤
I
LOAD
≤
3A,
18V
≤
V
IN
≤
40V
Circuit of
Figure 2
0.5A
≤
I
LOAD
≤
3A,
18V
≤
V
IN
≤
60V
Circuit of
Figure 2
V
IN
= 18V, I
LOAD
= 3A
88
15
14.40/14.25
15.68/15.83
15
14.40/14.25
15.60/15.75
15
14.70
15.30
V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
V(Max)
%
LM2576-15
LM2576HV-15
Limit
(Note 2)
Units
(Limits)
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