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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 Simple high-efficiency step-down (buck) regulator
n Efficient pre-regulator for linear regulators
n On-card switching regulators
n Positive to negative converter (Buck-Boost)
Typical Application (Fixed Output Voltage
Versions)
01147601
FIGURE 1.
SIMPLE SWITCHER ® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation
DS011476
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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 = 0
Ω
Patent Pending
Ordering Information
Temperature
Range
Output Voltage
NS Package Package
Type
3.3
5.0
12
15
ADJ
Number
−40˚C
≤
T A
LM2576HVS-3.3 LM2576HVS-5.0 LM2576HVS-12 LM2576HVS-15 LM2576HVS-ADJ
TS5B
TO-263
≤
125˚C
LM2576S-3.3 LM2576S-5.0 LM2576S-12 LM2576S-15 LM2576S-ADJ
LM2576HVSX-3.3 LM2576HVSX-5.0 LM2576HVSX-12 LM2576HVSX-15 LM2576HVSX-ADJ
TS5B
Tape & Reel
LM2576SX-3.3 LM2576SX-5.0 LM2576SX-12 LM2576SX-15 LM2576SX-ADJ
LM2576HVT-3.3 LM2576HVT-5.0 LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ
T05A
TO-220
LM2576T-3.3 LM2576T-5.0 LM2576T-12 LM2576T-15 LM2576T-ADJ
LM2576HVT-3.3 LM2576HVT-5.0 LM2576HVT-12 LM2576HVT-15 LM2576HVT-ADJ
T05D
Flow LB03
Flow LB03
Flow LB03
Flow LB03
Flow LB03
LM2576T-3.3
LM2576T-5.0
LM2576T-12
LM2576T-15
LM2576T-ADJ
Flow LB03
Flow LB03
Flow LB03
Flow LB03
Flow LB03
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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
LM2576
Minimum ESD Rating
(C = 100 pF, R = 1.5 k Ω )
2 kV
Lead Temperature
(Soldering, 10 Seconds)
260˚C
45V
Operating Ratings
Temperature Range
LM2576/LM2576HV
LM2576HV
63V
ON /OFF Pin Input Voltage
−0.3V
≤
V
≤
+V IN
−40˚C ≤ T J ≤ +125˚C
Output Voltage to Ground
(Steady State)
−1V
Supply Voltage
LM2576
40V
Power Dissipation
Internally Limited
LM2576HV
60V
Storage Temperature Range
−65˚C to +150˚C
Maximum Junction Temperature
150˚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
LM2576-3.3
Units
(Limits)
LM2576HV-3.3
Typ
Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V OUT
Output Voltage
V IN = 12V, I LOAD = 0.5A
3.3
V
Circuit of Figure 2
3.234
V(Min)
3.366
V(Max)
V OUT
Output Voltage
6V
≤
V IN
≤
40V, 0.5A
≤
I LOAD
≤
3A
3.3
V
LM2576
Circuit of Figure 2
3.168/ 3.135
V(Min)
3.432/ 3.465
V(Max)
V OUT
Output Voltage
6V
≤
V IN ≤
60V, 0.5A
≤
I LOAD ≤
3A
3.3
V
LM2576HV
Circuit of Figure 2
3.168/ 3.135
V(Min)
3.450/ 3.482
V(Max)
η
Efficiency
V IN = 12V, I LOAD =3A
75
%
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
LM2576-5.0
Units
(Limits)
LM2576HV-5.0
Typ
Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V OUT
Output Voltage
V IN = 12V, I LOAD = 0.5A
5.0
V
Circuit of Figure 2
4.900
V(Min)
5.100
V(Max)
V OUT
Output Voltage
0.5A
≤
I LOAD ≤
3A,
5.0
V
LM2576
8V
≤
V IN ≤
40V
4.800/ 4.750
V(Min)
Circuit of Figure 2
5.200/ 5.250
V(Max)
V OUT
Output Voltage
0.5A ≤ I LOAD ≤ 3A,
5.0
V
LM2576HV
8V
≤
V IN
≤
60V
4.800/ 4.750
V(Min)
Circuit of Figure 2
5.225/ 5.275
V(Max)
3
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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
LM2576-5.0
Units
(Limits)
LM2576HV-5.0
Typ
Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
η
Efficiency
V IN = 12V, I LOAD =3A
77
%
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
LM2576-12
Units
(Limits)
LM2576HV-12
Typ
Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V OUT
Output Voltage
V IN = 25V, I LOAD = 0.5A
12
V
Circuit of Figure 2
11.76
V(Min)
12.24
V(Max)
V OUT
Output Voltage
0.5A
≤
I LOAD
≤
3A,
12
V
LM2576
15V
≤
V IN ≤
40V
11.52/ 11.40
V(Min)
Circuit of Figure 2
12.48/ 12.60
V(Max)
V OUT
Output Voltage
0.5A
≤
I LOAD ≤
3A,
12
V
LM2576HV
15V ≤ V IN ≤ 60V
11.52/ 11.40
V(Min)
Circuit of Figure 2
12.54/ 12.66
V(Max)
η
Efficiency
V IN = 15V, I LOAD =3A
88
%
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
LM2576-15
Units
(Limits)
LM2576HV-15
Typ
Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V OUT
Output Voltage
V IN = 25V, I LOAD = 0.5A
15
V
Circuit of Figure 2
14.70
V(Min)
15.30
V(Max)
V OUT
Output Voltage
0.5A
≤
I LOAD ≤
3A,
15
V
LM2576
18V ≤ V IN ≤ 40V
14.40/ 14.25
V(Min)
Circuit of Figure 2
15.60/ 15.75
V(Max)
V OUT
Output Voltage
0.5A
≤
I LOAD
≤
3A,
15
V
LM2576HV
18V
≤
V IN ≤
60V
14.40/ 14.25
V(Min)
Circuit of Figure 2
15.68/ 15.83
V(Max)
η
Efficiency
V IN = 18V, I LOAD =3A
88
%
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LM2576-ADJ, LM2576HV-ADJ
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
LM2576-ADJ
Units
(Limits)
LM2576HV-ADJ
Typ
Limit
(Note 2)
SYSTEM PARAMETERS (Note 3) Test Circuit Figure 2
V OUT
Feedback Voltage
V IN = 12V, I LOAD = 0.5A
1.230
V
V OUT = 5V,
1.217
V(Min)
Circuit of Figure 2
1.243
V(Max)
V OUT
Feedback Voltage
0.5A
≤
I LOAD ≤
3A,
1.230
V
LM2576
8V ≤ V IN ≤ 40V
1.193/ 1.180
V(Min)
V OUT = 5V, Circuit of Figure 2
1.267/ 1.280
V(Max)
V OUT
Feedback Voltage
0.5A
≤
I LOAD
≤
3A,
1.230
V
LM2576HV
8V
≤
V IN ≤
60V
1.193/ 1.180
V(Min)
V OUT = 5V, Circuit of Figure 2
1.273/ 1.286
V(Max)
η
Efficiency
V IN = 12V, I LOAD = 3A, V OUT =5V
77
%
All Output Voltage Versions
Electrical Characteristics
Specifications with standard type face are for T J = 25˚C, and those with boldface type apply over full Operating Temperature
Range. Unless otherwise specified, V IN = 12V for the 3.3V, 5V, and Adjustable version, V IN = 25V for the 12V version, and V IN
= 30V for the 15V version. I LOAD = 500 mA.
Symbol
Parameter
Conditions
LM2576-XX
Units
(Limits)
LM2576HV-XX
Typ
Limit
(Note 2)
DEVICE PARAMETERS
I b
Feedback Bias Current
V OUT = 5V (Adjustable Version Only)
50
100/ 500
nA
f O
Oscillator Frequency
(Note 11)
52
kHz
47/ 42
kHz
(Min)
58/ 63
kHz
(Max)
V SAT
Saturation Voltage
I OUT = 3A (Note 4)
1.4
V
1.8/ 2.0
V(Max)
DC
Max Duty Cycle (ON)
(Note 5)
98
%
93
%(Min)
I CL
Current Limit
(Notes 4, 11)
5.8
A
4.2/ 3.5
A(Min)
6.9/ 7.5
A(Max)
I L
Output Leakage Current
(Notes 6, 7): Output = 0V
2
mA(Max)
Output = −1V
7.5
mA
Output = −1V
30
mA(Max)
I Q
Quiescent Current
(Note 6)
5
mA
10
mA(Max)
I STBY
Standby Quiescent
ON /OFF Pin = 5V (OFF)
50
µA
Current
200
µA(Max)
5
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