LM2575.PDF

August 2004

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 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)

01147501

Note: Pin numbers are for the TO-220 package.

SIMPLE SWITCHER ® is a registered trademark of National Semiconductor Corporation.

DS011475

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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 = 0

FIGURE 1.

Connection Diagrams (XX indicates output voltage option. See Ordering Information table for complete part

number.)

Straight Leads

5–Lead TO-220 (T)

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

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Ω

Note: Pin numbers are for the TO-220 package.

Connection Diagrams (XX indicates output voltage option. See Ordering Information table for complete part

number.) (Continued)

16–Lead DIP (N or J)

24-Lead Surface Mount (M)

01147525

*No Internal Connection

Top View

LM2575N-XX or LM2575HVN-XX

See NS Package Number N16A

LM1575J-XX-QML

See NS Package Number J16A

01147526

*No Internal Connection

Top View

LM2575M-XX or LM2575HVM-XX

See NS Package Number M24B

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

NSC

Standard

High

Temperature

Type

Package

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

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Ordering Information (Continued)

Package

NSC

Standard

High

Temperature

Type

Package

Voltage Rating

Range

Number

(40V)

(60V)

16-Pin Molded

N16A

LM2575N-5.0

LM2575HVN-5.0

−40˚C

≤

T J ≤

+125˚C

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-263

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

−55˚C

≤

T J ≤

+150˚C

LM1575J-15-QML

LM1575J-ADJ-QML

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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

LM1575/LM2575

Minimum ESD Rating

(C = 100 pF, R = 1.5 k Ω )

2 kV

Lead Temperature

(Soldering, 10 sec.)

260˚C

45V

Operating Ratings

Temperature Range

LM1575

LM2575HV

63V

ON /OFF Pin Input Voltage

−0.3V

≤

+V IN

−55˚C ≤ T J ≤ +150˚C

Output Voltage to Ground

(Steady State)

−1V

LM2575/LM2575HV

−40˚C ≤ T J ≤ +125˚C

Supply Voltage

LM1575/LM2575

Power Dissipation

Internally Limited

40V

Storage Temperature Range

−65˚C to +150˚C

LM2575HV

60V

Maximum Junction Temperature

150˚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

LM2575-3.3

Units

(Limits)

LM2575HV-3.3

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

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

≤

3.3

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 ≤

3.3

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

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

LM2575-5.0

Units

(Limits)

LM2575HV-5.0

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

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

LM1575/LM2575

≤

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

LM2575HV

≤

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)

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