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LM1575/LM2575/LM2575HV Series SIMPLE SWITCHER 1A Step-Down Voltage Regulator
May 1999
LM1575/LM2575/LM2575HV
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 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 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
n
n
n
Simple high-efficiency step-down (buck) regulator
Efficient pre-regualtor for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
Typical Application
Versions)
(Fixed Output Voltage
01147501
Note:
Pin numbers are for the TO-220 package.
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation.
© 2001 National Semiconductor Corporation
DS011475
www.national.com
LM1575/LM2575/LM2575HV
Block Diagram and Typical Application
01147502
3.3V, R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For ADJ. Version
R1 = Open, R2 = 0Ω
Note:
Pin numbers are for the TO-220 package.
FIGURE 1.
Connection Diagrams
number.)
Straight Leads
5–Lead TO-22 (T)
(XX indicates output voltage option. See Ordering Information table for complete part
Bent, Staggered Leads
5-Lead TO-220 (T)
01147522
01147523
01147524
Top View
LM2575T-XX or LM2575HVT-XX
See NS Package Number T05A
Top View
Side View
LM2575T-XX Flow LB03 or
LM2575HVT-XX Flow LB03
See NS Package Number T05D
24-Lead Surface Mount (M)
16–Lead DIP (N or J)
01147525
Top View
LM2575N-XX or LM2575HVN-XX
See NS Package Number N16A
LM1575J-XX-QML
See NS Package Number J16A
*No Internal Connection
01147526
Top View
LM2575M-XX or LM2575HVM-XX
See NS Package Number M24B
*No Internal Connection
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2
LM1575/LM2575/LM2575HV
Connection Diagrams
number.) (Continued)
(XX indicates output voltage option. See Ordering Information table for complete part
TO-263(S)
5-Lead Surface-Mount Package
01147529
Top View
01147530
Side View
LM2575S-XX or LM2575HVS-XX
See NS Package Number TS5B
Ordering Information
Package
Type
5-Lead TO-220
Straight Leads
NSC
Package
Number
T05A
Standard
Voltage Rating
(40V)
LM2575T-3.3
LM2575T-5.0
LM2575T-12
LM2575T-15
LM2575T-ADJ
5-Lead TO-220
Bent and
Staggered Leads
T05D
LM2575T-3.3 Flow LB03
LM2575T-5.0 Flow LB03
LM2575T-12 Flow LB03
LM2575T-15 Flow LB03
LM2575T-ADJ Flow LB03
16-Pin Molded
DIP
N16A
LM2575N-5.0
LM2575N-12
LM2575N-15
LM2575N-ADJ
24-Pin
Surface Mount
M24B
LM2575M-5.0
LM2575M-12
LM2575M-15
LM2575M-ADJ
5-Lead TO-236
Surface Mount
TS5B
LM2575S-3.3
LM2575S-5.0
LM2575S-12
LM2575S-15
LM2575S-ADJ
16-Pin Ceramic
DIP
J16A
LM1575J-3.3-QML
LM1575J-5.0-QML
LM1575J-12-QML
LM1575J-15-QML
LM1575J-ADJ-QML
−55˚C
≤
T
J
≤
+150˚C
High
Voltage Rating
(60V)
LM2575HVT-3.3
LM2575HVT-5.0
LM2575HVT-12
LM2575HVT-15
LM2575HVT-ADJ
LM2575HVT-3.3 Flow LB03
LM2575HVT-5.0 Flow LB03
LM2575HVT-12 Flow LB03
LM2575HVT-15 Flow LB03
LM2575HVT-ADJ Flow LB03
LM2575HVN-5.0
LM2575HVN-12
LM2575HVN-15
LM2575HVN-ADJ
LM2575HVM-5.0
LM2575HVM-12
LM2575HVM-15
LM2575HVM-ADJ
LM2575HVS-3.3
LM2575HVS-5.0
LM2575HVS-12
LM2575HVS-15
LM2575HVS-ADJ
−40˚C
≤
T
J
≤
+125˚C
Temperature
Range
3
www.national.com
LM1575/LM2575/LM2575HV
Absolute Maximum Ratings
(Note 1)
Minimum ESD Rating
(C = 100 pF, R = 1.5 kΩ)
Lead Temperature
(Soldering, 10 sec.)
260˚C
2 kV
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Maximum Supply Voltage
LM1575/LM2575
LM2575HV
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
Operating Ratings
Temperature Range
LM1575
LM2575/LM2575HV
Supply Voltage
LM1575/LM2575
LM2575HV
40V
60V
−55˚C
≤
T
J
≤
+150˚C
−40˚C
≤
T
J
≤
+125˚C
LM1575-3.3, LM2575-3.3, LM2575HV-3.3
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range
.
Symbol
Parameter
Conditions
Typ
LM1575-3.3
Limit
(Note 2)
SYSTEM PARAMETERS
(Note 4) Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 12V, I
LOAD
= 0.2A
Circuit of
Figure 2
V
OUT
Output Voltage
LM1575/LM2575
V
OUT
Output Voltage
LM2575HV
η
Efficiency
4.75V
≤
V
IN
≤
40V, 0.2A
≤
I
LOAD
≤
1A
Circuit of
Figure 2
4.75V
≤
V
IN
≤
60V, 0.2A
≤
I
LOAD
≤
1A
Circuit of
Figure 2
V
IN
= 12V, I
LOAD
= 1A
75
3.3
3.200/3.168
3.416/3.450
3.168/3.135
3.450/3.482
3.3
3.200/3.168
3.400/3.432
3.168/3.135
3.432/3.465
3.3
3.267
3.333
3.234
3.366
V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
V(Max)
%
Units
LM2575HV-3.3 (Limits)
Limit
(Note 3)
LM2575-3.3
LM1575-5.0, LM2575-5.0, LM2575HV-5.0
Electrical Characteristics
Specifications with standard type face are for T
J
= 25˚C, and those with
boldface type
apply over
full Operating Tempera-
ture Range.
Symbol
Parameter
Conditions
Typ
LM1575-5.0
Limit
(Note 2)
SYSTEM PARAMETERS
(Note 4) Test Circuit
Figure 2
V
OUT
Output Voltage
V
IN
= 12V, I
LOAD
= 0.2A
Circuit of
Figure 2
V
OUT
Output Voltage
LM1575/LM2575
V
OUT
Output Voltage
LM2575HV
0.2A
≤
I
LOAD
≤
1A,
8V
≤
V
IN
≤
40V
Circuit of
Figure 2
0.2A
≤
I
LOAD
≤
1A,
8V
≤
V
IN
≤
60V
5.0
4.850/4.800
4.800/4.750
5.0
4.850/4.800
5.150/5.200
4.800/4.750
5.200/5.250
5.0
4.950
5.050
4.900
5.100
V
V(Min)
V(Max)
V
V(Min)
V(Max)
V
V(Min)
LM2575-5.0
LM2575HV-5.0
Limit
(Note 3)
Units
(Limits)
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