LM1575/LM2575/LM2575HV Series
SIMPLE SWITCHER
1A Step-Down Voltage Regulator
General Description
The LM2575 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 1A 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 LM2575 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially re-
duces the size of the heat sink, and in many cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2575 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 1A 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-regualtor 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.
DS011475-1
Note: Pin numbers are for the TO-220 package.
May 1999
LM1575/LM2575/LM2575HV
Series
SIMPLE
SWITCHER
1A
Step-Down
V
oltage
Regulator
1999 National Semiconductor Corporation
DS011475
www.national.com
Block Diagram and Typical Application
Connection Diagrams
(XX indicates output voltage option. See Ordering Information table for complete part
number.)
DS011475-2
3.3V, R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For ADJ. Version
R1 = Open, R2 = 0
Note: Pin numbers are for the TO-220 package.
FIGURE 1.
Straight Leads
5Lead TO-22 (T)
DS011475-22
Top View
LM2575T-XX or LM2575HVT-XX
See NS Package Number T05A
Bent, Staggered Leads
5-Lead TO-220 (T)
DS011475-23
Top View
DS011475-24
Side View
LM2575T-XX Flow LB03 or
LM2575HVT-XX Flow LB03
See NS Package Number T05D
16Lead DIP (N or J)
DS011475-25
*No Internal Connection
Top View
LM2575N-XX or LM2575HVN-XX
See NS Package Number N16A
LM1575J-XX-QML
See NS Package Number J16A
24-Lead Surface Mount (M)
DS011475-26
*No Internal Connection
Top View
LM2575M-XX or LM2575HVM-XX
See NS Package Number M24B
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2
Connection Diagrams
(XX indicates output voltage option. See Ordering Information table for complete part
number.) (Continued)
Ordering Information
Package
NSC
Standard
High
Temperature
Type
Package
Voltage Rating
Voltage Rating
Range
Number
(40V)
(60V)
5-Lead TO-220
T05A
LM2575T-3.3
LM2575HVT-3.3
Straight Leads
LM2575T-5.0
LM2575HVT-5.0
LM2575T-12
LM2575HVT-12
LM2575T-15
LM2575HVT-15
LM2575T-ADJ
LM2575HVT-ADJ
5-Lead TO-220
T05D
LM2575T-3.3 Flow LB03
LM2575HVT-3.3 Flow LB03
Bent and
LM2575T-5.0 Flow LB03
LM2575HVT-5.0 Flow LB03
Staggered Leads
LM2575T-12 Flow LB03
LM2575HVT-12 Flow LB03
LM2575T-15 Flow LB03
LM2575HVT-15 Flow LB03
LM2575T-ADJ Flow LB03
LM2575HVT-ADJ Flow LB03
16-Pin Molded
N16A
LM2575N-5.0
LM2575HVN-5.0
-40C
T
J
+125C
DIP
LM2575N-12
LM2575HVN-12
LM2575N-15
LM2575HVN-15
LM2575N-ADJ
LM2575HVN-ADJ
24-Pin
M24B
LM2575M-5.0
LM2575HVM-5.0
Surface Mount
LM2575M-12
LM2575HVM-12
LM2575M-15
LM2575HVM-15
LM2575M-ADJ
LM2575HVM-ADJ
5-Lead TO-236
TS5B
LM2575S-3.3
LM2575HVS-3.3
Surface Mount
LM2575S-5.0
LM2575HVS-5.0
LM2575S-12
LM2575HVS-12
LM2575S-15
LM2575HVS-15
LM2575S-ADJ
LM2575HVS-ADJ
16-Pin Ceramic
J16A
LM1575J-3.3-QML
DIP
LM1575J-5.0-QML
LM1575J-12-QML
-55C
T
J
+150C
LM1575J-15-QML
LM1575J-ADJ-QML
TO-263(S)
5-Lead Surface-Mount Package
DS011475-29
Top View
DS011475-30
Side View
LM2575S-XX or LM2575HVS-XX
See NS Package Number TS5B
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3
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
LM1575/LM2575
45V
LM2575HV
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 sec.)
260C
Operating Ratings
Temperature Range
LM1575
-55C
T
J
+150C
LM2575/LM2575HV
-40C
T
J
+125C
Supply Voltage
LM1575/LM2575
40V
LM2575HV
60V
LM1575-3.3, LM2575-3.3, LM2575HV-3.3
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, and those with boldface type apply over full Operating Tempera-
ture Range .
Symbol
Parameter
Conditions
Typ
LM1575-3.3
LM2575-3.3
Units
(Limits)
LM2575HV-3.3
Limit
Limit
(Note 2)
(Note 3)
SYSTEM PARAMETERS (Note 4) Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 12V, I
LOAD
= 0.2A
3.3
V
Circuit of
Figure 2
3.267
3.234
V(Min)
3.333
3.366
V(Max)
V
OUT
Output Voltage
4.75V
V
IN
40V, 0.2A
I
LOAD
1A
3.3
V
LM1575/LM2575
Circuit of
Figure 2
3.200/3.168
3.168/3.135
V(Min)
3.400/3.432
3.432/3.465
V(Max)
V
OUT
Output Voltage
4.75V
V
IN
60V, 0.2A
I
LOAD
1A
3.3
V
LM2575HV
Circuit of
Figure 2
3.200/3.168
3.168/3.135
V(Min)
3.416/3.450
3.450/3.482
V(Max)
Efficiency
V
IN
= 12V, I
LOAD
= 1A
75
%
LM1575-5.0, LM2575-5.0, LM2575HV-5.0
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, and those with boldface type apply over full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
Typ
LM1575-5.0
LM2575-5.0
Units
(Limits)
LM2575HV-5.0
Limit
Limit
(Note 2)
(Note 3)
SYSTEM PARAMETERS (Note 4) Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 12V, I
LOAD
= 0.2A
5.0
V
Circuit of
Figure 2
4.950
4.900
V(Min)
5.050
5.100
V(Max)
V
OUT
Output Voltage
0.2A
I
LOAD
1A,
5.0
V
LM1575/LM2575
8V
V
IN
40V
4.850/4.800
4.800/4.750
V(Min)
Circuit of
Figure 2
5.150/5.200
5.200/5.250
V(Max)
V
OUT
Output Voltage
0.2A
I
LOAD
1A,
5.0
V
LM2575HV
8V
V
IN
60V
4.850/4.800
4.800/4.750
V(Min)
Circuit of
Figure 2
5.175/5.225
5.225/5.275
V(Max)
Efficiency
V
IN
= 12V, I
LOAD
= 1A
77
%
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LM1575-12, LM2575-12, LM2575HV-12
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, and those with boldface type apply over full Operating Tempera-
ture Range .
Symbol
Parameter
Conditions
Typ
LM1575-12
LM2575-12
Units
(Limits)
LM2575HV-12
Limit
Limit
(Note 2)
(Note 3)
SYSTEM PARAMETERS (Note 4) Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 25V, I
LOAD
= 0.2A
12
V
Circuit of
Figure 2
11.88
11.76
V(Min)
12.12
12.24
V(Max)
V
OUT
Output Voltage
0.2A
I
LOAD
1A,
12
V
LM1575/LM2575
15V
V
IN
40V
11.64/11.52
11.52/11.40
V(Min)
Circuit of
Figure 2
12.36/12.48
12.48/12.60
V(Max)
V
OUT
Output Voltage
0.2A
I
LOAD
1A,
12
V
LM2575HV
15V
V
IN
60V
11.64/11.52
11.52/11.40
V(Min)
Circuit of
Figure 2
12.42/12.54
12.54/12.66
V(Max)
Efficiency
V
IN
= 15V, I
LOAD
= 1A
88
%
LM1575-15, LM2575-15, LM2575HV-15
Electrical Characteristics
Specifications with standard type face are for T
J
= 25C, and those with boldface type apply over full Operating Tempera-
ture Range .
Symbol
Parameter
Conditions
Typ
LM1575-15
LM2575-15
Units
(Limits)
LM2575HV-15
Limit
Limit
(Note 2)
(Note 3)
SYSTEM PARAMETERS (Note 4) Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 30V, I
LOAD
= 0.2A
15
V
Circuit of
Figure 2
14.85
14.70
V(Min)
15.15
15.30
V(Max)
V
OUT
Output Voltage
0.2A
I
LOAD
1A,
15
V
LM1575/LM2575
18V
V
IN
40V
14.55/14.40
14.40/14.25
V(Min)
Circuit of
Figure 2
15.45/15.60
15.60/15.75
V(Max)
V
OUT
Output Voltage
0.2A
I
LOAD
1A,
15
V
LM2575HV
18V
V
IN
60V
14.55/14.40
14.40/14.25
V(Min)
Circuit of
Figure 2
15.525/15.675
15.68/15.83
V(Max)
Efficiency
V
IN
= 18V, I
LOAD
= 1A
88
%
LM1575-ADJ, LM2575-ADJ, LM2575HV-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
Typ
LM1575-ADJ
LM2575-ADJ
Units
(Limits)
LM2575HV-ADJ
Limit
Limit
(Note 2)
(Note 3)
SYSTEM PARAMETERS (Note 4) Test Circuit
Figure 2
V
OUT
Feedback Voltage
V
IN
= 12V, I
LOAD
= 0.2A
1.230
V
V
OUT
= 5V
1.217
1.217
V(Min)
Circuit of
Figure 2
1.243
1.243
V(Max)
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