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 A (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)
SIMPLE SWITCHER
is a registered trademark of National Semiconductor Corporation.
01147601
FIGURE 1.
August 2004
LM2576/LM2576HV
Series
SIMPLE
SWITCHER
3A
Step-Down
V
oltage
Regulator
2004 National Semiconductor Corporation
DS011476
www.national.com
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
45V
LM2576HV
63V
ON /OFF Pin Input Voltage
-0.3V
V +V
IN
Output Voltage to Ground
(Steady State)
-1V
Power Dissipation
Internally Limited
Storage Temperature Range
-65C to +150C
Maximum Junction Temperature
150C
Minimum ESD Rating
(C = 100 pF, R = 1.5 k
)
2 kV
Lead Temperature
(Soldering, 10 Seconds)
260C
Operating Ratings
Temperature Range
LM2576/LM2576HV
-40C
T
J
+125C
Supply Voltage
LM2576
40V
LM2576HV
60V
LM2576-3.3, LM2576HV-3.3
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, 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)
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
= 25C, 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)
LM2576/LM2576HV
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3
LM2576-5.0, LM2576HV-5.0
Electrical Characteristics
(Continued)
Specifications with standard type face are for T
J
= 25C, 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
Efficiency
V
IN
= 12V, I
LOAD
= 3A
77
%
LM2576-12, LM2576HV-12
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, 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)
Efficiency
V
IN
= 15V, I
LOAD
= 3A
88
%
LM2576-15, LM2576HV-15
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, 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)
Efficiency
V
IN
= 18V, I
LOAD
= 3A
88
%
LM2576/LM2576HV
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4
LM2576-ADJ, LM2576HV-ADJ
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, 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)
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
= 25C, 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
A
Current
200
A(Max)
LM2576/LM2576HV
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