NSC LM2574HVM-ADJ, LM2574HVM-5.0, LM2574HVM-3.3, LM2574HVM-12, LM2574HVN-3.3 Datasheet

LM2574/LM2574HV
SIMPLE SWITCHER

™

0.5A Step-Down Voltage Regulator

General Description

The LM2574 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 0.5A load
with excellent line and load regulation. These devices are
available in fixed output voltages of 3.3V, 5V, 12V, 15V, and
an adjustable output version.

Requiring aminimumnumber of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.

The LM2574 series offers a high-efficiency replacement for
popular three-terminal linear regulators. Because of its high
efficiency, the copper traces on the printed circuit board are
normally the only heat sinking needed.

A standard series of inductors optimized for use with the
LM2574 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 out­put voltage within specified input voltages and output load
conditions, and

±

10%on the oscillator frequency. External
shutdown is included, featuring 50 µA (typical) standby cur­rent. The output switch includes cycle-by-cycle current limit­ing, 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 0.5A 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

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)

Patent Pending
SIMPLE SWITCHER

™

is a trademark of National Semiconductor Corporation

DS011394-1

Note: Pin numbers are for 8-pin DIP package.

June 1999

LM2574/LM2574HV SIMPLE SWITCHER 0.5A Step-Down Voltage Regulator

© 1999 National Semiconductor Corporation DS011394 www.national.com

Connection Diagrams

8-Lead DIP

DS011394-2

* No internal connection, but should be soldered to PC board for best heat
transfer.

Top View

Order Number LM2574-3.3HVN, LM2574HVN-5.0,

LM2574HVN-12, LM2574HVN-15, LM2574HVN-ADJ,

LM2574N-3.3, LM2574N-5.0, LM2574N-12,

LM2574N-15 or LM2574N-ADJ

See NS Package Number N08A

14-Lead Wide

Surface Mount (WM)

DS011394-3

Top View

Order Number LM2574HVM-3.3, LM2574HVM-5.0,

LM2574HVM-12, LM2574HVM-15, LM2574HVM-ADJ,

LM2574M-3.3 LM2574M-5.0, LM2574M-12,

LM2574M-15 or LM2574M-ADJ

See NS Package Number M14B

www.national.com 2

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

LM2574 45V
LM2574HV 63V

ON /OFF Pin Input Voltage

−0.3V ≤ V ≤ +V

IN

Output Voltage to Ground

(Steady State) −1V

Minimum ESD Rating

(C=100 pF, R=1.5 kΩ)2kV

Storage Temperature Range −65˚C to +150˚C

Lead Temperature

(Soldering, 10 seconds) 260˚C
Maximum Junction Temperature 150˚C
Power Dissipation Internally Limited

Operating Ratings

Temperature Range

LM2574/LM2574HV −40˚C ≤ T

J

≤ +125˚C

Supply Voltage

LM2574 40V

LM2574HV 60V

LM2574-3.3, LM2574HV-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 LM2574-3.3 Units

(Limits)

LM2574HV-3.3

Typ Limit

(Note 2)

SYSTEM PARAMETERS (Note 3) Test Circuit

Figure 2

V

OUT

Output Voltage V

IN

=

12V, I

LOAD

=

100 mA 3.3 V

3.234 V(Min)

3.366 V(Max)

V

OUT

Output Voltage 4.75V ≤ VIN≤ 40V, 0.1A ≤ I

LOAD

≤ 0.5A 3.3 V

LM2574 3.168/3.135 V(Min)

3.432/3.465 V(Max)

V

OUT

Output Voltage 4.75V ≤ VIN≤ 60V, 0.1A ≤ I

LOAD

≤ 0.5A 3.3

LM2574HV 3.168/3.135 V(Min)

3.450/3.482 V(Max)

η Efficiency V

IN

=

12V, I

LOAD

=

0.5A 72

%

LM2574-5.0, LM2574HV-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 LM2574-5.0 Units

(Limits)

LM2574HV-5.0

Typ Limit

(Note 2)

SYSTEM PARAMETERS (Note 3) Test Circuit

Figure 2

V

OUT

Output Voltage V

IN

=

12V, I

LOAD

=

100 mA 5 V

4.900 V(Min)

5.100 V(Max)

V

OUT

Output Voltage 7V ≤ VIN≤ 40V, 0.1A ≤ I

LOAD

≤ 0.5A 5 V

LM2574 4.800/4.750 V(Min)

5.200/5.250 V(Max)

V

OUT

Output Voltage 7V ≤ VIN≤ 60V, 0.1A ≤ I

LOAD

≤ 0.5A 5

LM2574HV 4.800/4.750 V(Min)

5.225/5.275 V(Max)

η Efficiency V

IN

=

12V, I

LOAD

=

0.5A 77

%

www.national.com3

LM2574-12, LM2574HV-12
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 LM2574-12 Units

(Limits)

LM2574HV-12

Typ Limit

(Note 2)

SYSTEM PARAMETERS (Note 3) Test Circuit

Figure 2

V

OUT

Output Voltage V

IN

=

25V, I

LOAD

=

100 mA 12 V

11.76 V(Min)

12.24 V(Max)

V

OUT

Output Voltage 15V ≤ VIN≤ 40V, 0.1A ≤ I

LOAD

≤ 0.5A 12 V

LM2574 11.52/11.40 V(Min)

12.48/12.60 V(Max)

V

OUT

Output Voltage 15V ≤ VIN≤ 60V, 0.1A ≤ I

LOAD

≤ 0.5A 12

LM2574HV 11.52/11.40 V(Min)

12.54/12.66 V(Max)

η Efficiency V

IN

=

15V, I

LOAD

=

0.5A 88

%

LM2574-15, LM2574HV-15
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 LM2574-15 Units

(Limits)

LM2574HV-15

Typ Limit

(Note 2)

SYSTEM PARAMETERS (Note 3) Test Circuit

Figure 2

V

OUT

Output Voltage V

IN

=

30V, I

LOAD

=

100 mA 15 V

14.70 V(Min)

15.30 V(Max)

V

OUT

Output Voltage 18V ≤ VIN≤ 40V, 0.1A ≤ I

LOAD

≤ 0.5A 15 V

LM2574 14.40/14.25 V(Min)

15.60/15.75 V(Max)

V

OUT

Output Voltage 18V ≤ VIN≤ 60V, 0.1A ≤ I

LOAD

≤ 0.5A 15

LM2574HV 14.40/14.25 V(Min)

15.68/15.83 V(Max)

η Efficiency V

IN

=

18V, I

LOAD

=

0.5A 88

%

LM2574-ADJ, LM2574HV-ADJ
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. Unless otherwise specified, V

IN

=

12V, I

LOAD

=

100 mA.

Symbol Parameter Conditions LM2574-ADJ Units

(Limits)

LM2574HV-ADJ

Typ Limit

(Note 2)

SYSTEM PARAMETERS (Note 3) Test Circuit

Figure 2

V

FB

Feedback Voltage V

IN

=

12V, I

LOAD

=

100 mA 1.230 V

1.217 V(Min)

1.243 V(Max)

www.national.com 4

LM2574-ADJ, LM2574HV-ADJ
Electrical Characteristics

(Continued)

Specifications with standard type face are for T

J

=

25˚C, and those with boldface type apply over full Operating Tempera-

ture Range. Unless otherwise specified, V

IN

=

12V, I

LOAD

=

100 mA.

Symbol Parameter Conditions LM2574-ADJ Units

(Limits)

LM2574HV-ADJ

Typ Limit

(Note 2)

SYSTEM PARAMETERS (Note 3) Test Circuit

Figure 2

V

FB

Feedback Voltage 7V ≤ VIN≤ 40V, 0.1A ≤ I

LOAD

≤ 0.5A 1.230 V

LM2574 V

OUT

Programmed for 5V. Circuit of

Figure 2

1.193/1.180 V(Min)

1.267/1.280 V(Max)

V

FB

Feedback Voltage 7V ≤ VIN≤ 60V, 0.1A ≤ I

LOAD

≤ 0.5A 1.230

LM2574HV V

OUT

Programmed for 5V. Circuit of

Figure 2

1.193/1.180 V(Min)

1.273/1.286 V(Max)

η Efficiency V

IN

=

12V, V

OUT

=

5V, I

LOAD

=

0.5A 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 Tempera-

ture 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

=

100 mA.

Symbol Parameter Conditions LM2574-XX Units

(Limits)

LM2574HV-XX

Typ Limit

(Note 2)

DEVICE PARAMETERS

I

b

Feedback Bias
Current

Adjustable Version Only, V

OUT

=

5V 50 100/500 nA

f

O

Oscillator Frequency (see Note 10) 52 kHz

47/42 kHz(Min)
58/63 kHz(Max)

V

SAT

Saturation Voltage I

OUT

=

0.5A (Note 4) 0.9 V

1.2/1.4 V(max)

DC Max Duty Cycle

(ON)

(Note 5) 98

%

93

%

(Min)

I

CL

Current Limit Peak Current, (Notes 4, 10) 1.0 A

0.7/0.65 A(Min)

1.6/1.8 A(Max)

I

L

Output Leakage (Notes 6, 7) Output=0V 2 mA(Max)
Current 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)

θ

JA

Thermal Resistance N Package, Junction to Ambient (Note 8) 92

θ

JA

N Package, Junction to Ambient (Note 9) 72 ˚C/W

θ

JA

M Package, Junction to Ambient (Note 8) 102

θ

JA

M Package, Junction to Ambient (Note 9) 78

www.national.com5

All Output Voltage Versions
Electrical Characteristics

(Continued)

Specifications with standard type face are for T

J

=

25˚C, and those with boldface type apply over full Operating Tempera-

ture 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

=

100 mA.

Symbol Parameter Conditions LM2574-XX Units

(Limits)

LM2574HV-XX

Typ Limit

(Note 2)

ON /OFF CONTROL Test Circuit

Figure 2

V

IH

ON /OFF Pin Logic V

OUT

=

0V 1.4 2.2/2.4 V(Min)

V

IL

Input Level V

OUT

=

Nominal Output Voltage 1.2 1.0/0.8 V(Max)

I

H

ON /OFF Pin Input ON /OFF Pin=5V (OFF) 12 µA
Current 30 µA(Max)

I

IL

ON /OFF Pin=0V (ON) 0µA

10 µA(Max)

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.Operating Ratings indicate conditions for which the device is in­tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: All limits guaranteed at room temperature (Standard type face) and at temperature extremes (bold type face). All room temperature limits are 100%produc-
tion tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate
Average Outgoing Quality Level.

Note 3: External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2574
is used as shown in the

Figure 2

test circuit, system performance will be as shown in system parameters section of Electrical Characteristics.

Note 4: Output pin sourcing current. No diode, inductor or capacitor connected to output pin.
Note 5: Feedback pin removed from output and connected to 0V.
Note 6: Feedback pin removed from output and connected to +12V for the Adjustable, 3.3V,and 5V versions, and +25V for the 12V and 15V versions, to force the

output transistor OFF.
Note 7: V

IN

=

40V (60V for high voltage version).

Note 8: Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional copper area will
lower thermal resistance further. See application hints in this data sheet and the thermal model in Switchers Made Simple software.

Note 9: Junction to ambient thermal resistance with approximately 4 square inches of 1 oz. (0.0014 in. thick) printed circuit board copper surrounding the leads. Ad­ditional copper area will lower thermal resistance further. (See Note 8.)

Note 10: The oscillator frequency reduces to approximately 18 kHz in the event of an output short or an overload which causes the regulated output voltage to drop
approximately 40%from the nominal output voltage. This self protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycle
from 5%down to approximately 2%.

Typical Performance Characteristics (Circuit of

Figure 2

)

Normalized Output Voltage

DS011394-27

Line Regulation

DS011394-28

Dropout Voltage

DS011394-29

www.national.com 6

Typical Performance Characteristics (Circuit of

Figure 2

) (Continued)

Current Limit

DS011394-30

Supply Current

DS011394-31

Standby
Quiescent Current

DS011394-32

Oscillator Frequency

DS011394-33

Switch Saturation
Voltage

DS011394-34

Efficiency

DS011394-35

Minimum Operating Voltage

DS011394-36

Supply Current
vs Duty Cycle

DS011394-37

Feedback Voltage
vs Duty Cycle

DS011394-38

www.national.com7

Typical Performance Characteristics (Circuit of

Figure 2

) (Continued)

Feedback
Pin Current

DS011394-39

Junction to Ambient
Thermal Resistance

DS011394-40

Continuous Mode Switching Waveforms
V

OUT

=

5V, 500 mA Load Current, L=330 µH

DS011394-6

Notes:

A: Output Pin Voltage, 10V/div
B: Inductor Current, 0.2 A/div
C: Output Ripple Voltage, 20 mV/div,
AC-Coupled
Horizontal Time Base: 5 µs/div

Discontinuous Mode Switching Waveforms
V

OUT

=

5V, 100 mA Load Current, L=100 µH

DS011394-7

Notes:

A: Output Pin Voltage, 10V/div
B: Inductor Current, 0.2 A/div
C: Output Ripple Voltage, 20 mV/div,
AC-Coupled
Horizontal Time Base: 5 µs/div

500 mA Load Transient Response for Continuous
Mode Operation. L=330 µH, C

OUT

=

300 µF

DS011394-8

Notes:

A: Output Voltage, 50 mV/div.
AC Coupled
B: 100 mA to 500 mA Load Pulse
Horizontal Time Base: 200 µs/div

250 mA Load Transient Response for Discontinuous
Mode Operation. L=68 µH, C

OUT

=

470 µF

DS011394-9

Notes:

A: Output Voltage, 50 mV/div.
AC Coupled
B: 50 mA to 250 mA Load Pulse
Horizontal Time Base: 200 µs/div

www.national.com 8