LM2575T-ADJ_技术文档

LM2575, NCV2575

1.0 A, Adjustable Output

Voltage, Step-Down

Switching Regulator

The LM2575 series of regulators are monolithic integrated circuits

ideally suited for easy and convenient design of a step−down

switching regulator (buck converter). All circuits of this series are

capable of driving a 1.0 A load with excellent line and load regulation.

These devices are available in fixed output voltages of 3.3 V, 5.0 V,

12 V, 15 V, and an adjustable output version.

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TO−220

These regulators were designed to minimize the number of external

components to simplify the power supply design. Standard series of

inductors optimized for use with the LM2575 are offered by several

different inductor manufacturers.

Since the LM2575 converter is a switch−mode power supply, its

efficiency is significantly higher in comparison with popular

three−terminal linear regulators, especially with higher input voltages.

In many cases, the power dissipated by the LM2575 regulator is so

low, that no heatsink is required or its size could be reduced

dramatically.

The LM2575 features include a guaranteed 4% tolerance on output

voltage within specified input voltages and output load conditions, and

10% on the oscillator frequency ( 2% over 0°C to 125°C). External

shutdown is included, featuring 80 mA typical standby current. The

output switch includes cycle−by−cycle current limiting, as well as

thermal shutdown for full protection under fault conditions.

TV SUFFIX

CASE 314B

1

5

Heatsink surface connected to Pin 3

TO−220

T SUFFIX

CASE 314D

1

5

Pin 1.

V

in

2. Output

Features

3. Ground

4. Feedback

5. ON/OFF

• 3.3 V, 5.0 V, 12 V, 15 V, and Adjustable Output Versions

• Adjustable Version Output Voltage Range of 1.23 V to 37 V 4%

Maximum Over Line and Load Conditions

• Guaranteed 1.0 A Output Current

• Wide Input Voltage Range: 4.75 V to 40 V

• Requires Only 4 External Components

• 52 kHz Fixed Frequency Internal Oscillator

• TTL Shutdown Capability, Low Power Standby Mode

• High Efficiency

• Uses Readily Available Standard Inductors

• Thermal Shutdown and Current Limit Protection

• Moisture Sensitivity Level (MSL) Equals 1

• Pb−Free Packages are Available*

2

D PAK

D2T SUFFIX

CASE 936A

1

5

Heatsink surface (shown as terminal 6 in

case outline drawing) is connected to Pin 3

ORDERING INFORMATION

See detailed ordering and shipping information in the package

dimensions section on page 25 of this data sheet.

Applications

• Simple and High−Efficiency Step−Down (Buck) Regulators

• Efficient Pre−Regulator for Linear Regulators

• On−Card Switching Regulators

DEVICE MARKING INFORMATION

See general marking information in the device marking

section on page 27 of this data sheet.

• Positive to Negative Converters (Buck−Boost)

• Negative Step−Up Converters

• Power Supply for Battery Chargers

*For additional information on our Pb−Free strategy and soldering details, please

download the ON Semiconductor Soldering and Mounting Techniques

Reference Manual, SOLDERRM/D.

1

Publication Order Number:

September, 2008 − Rev. 10

LM2575/D

LM2575, NCV2575

Typical Application (Fixed Output Voltage Versions)

Feedback

4

L1

330 mH

7.0 V - 40 V

Unregulated

DC Input

+V

in

LM2575

Output

2

1

5.0 V Regulated

Output 1.0 A Load

C

in

100 mF

D1

1N5819

C

out

330 mF

3

GND 5 ON/OFF

Representative Block Diagram and Typical Application

Unregulated

DC Input

+V

in

ON/OFF

5

3.1 V Internal

Regulator

Output

Voltage Versions

R2

(W)

ON/OFF

1

C

in

3.3 V

5.0 V

12 V

15 V

1.7 k

3.1 k

8.84 k

11.3 k

4

Feedback

Current

Limit

For adjustable version

R1 = open, R2 = 0 W

R2

Fixed Gain

Error Amplifier

Comparator

Driver

Regulated

Output

R1

1.0 k

Latch

Freq

Shift

L1

V

out

Output

18 kHz

1.0 Amp

Switch

2

GND

1.235 V

Band-Gap

Reference

C

out

D1

Thermal

Shutdown

52 kHz

Oscillator

3

Reset

Load

This device contains 162 active transistors.

Figure 1. Block Diagram and Typical Application

ABSOLUTE MAXIMUM RATINGS (Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.)

Rating

Symbol

Value

45

Unit

V

Maximum Supply Voltage

ON/OFF Pin Input Voltage

V

in

−

−0.3 V ≤ V ≤ +V

−1.0

V

in

Output Voltage to Ground (Steady−State)

−

V

Power Dissipation

Case 314B and 314D (TO−220, 5−Lead)

Thermal Resistance, Junction−to−Ambient

Thermal Resistance, Junction−to−Case

P

Internally Limited

W

D

R

65

5.0

°C/W

W

q

JA

JC

D

q

2

Case 936A (D PAK)

P

Internally Limited

Thermal Resistance, Junction−to−Ambient (Figure 34)

Thermal Resistance, Junction−to−Case

R

70

5.0

°C/W

q

JA

JC

R

q

Storage Temperature Range

T

−65 to +150

2.0

°C

kV

°C

stg

Minimum ESD Rating (Human Body Model: C = 100 pF, R = 1.5 kW)

Lead Temperature (Soldering, 10 s)

−

260

Maximum Junction Temperature

T

150

J

Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the

Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect

device reliability.

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2

LM2575, NCV2575

OPERATING RATINGS (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.)

Rating

Operating Junction Temperature Range

Symbol

Value

−40 to +125

40

Unit

°C

T

J

Supply Voltage

V

in

V

SYSTEM PARAMETERS ([Note 1] Test Circuit Figure 14)

ELECTRICAL CHARACTERISTICS (Unless otherwise specified, V = 12 V for the 3.3 V, 5.0 V, and Adjustable version, V = 25 V

in

for the 12 V version, and V = 30 V for the 15 V version. I

= 200 mA. For typical values T = 25°C, for min/max values T is the

in

Load

J

operating junction temperature range that applies [Note 2], unless otherwise noted.)

Characteristics

Symbol

Min

Typ

Max

Unit

LM2575−3.3 (Note 1 Test Circuit Figure 14)

Output Voltage (V = 12 V, I

= 0.2 A, T = 25°C)

V

out

3.234

3.3

3.366

V

in

Load

J

Output Voltage (4.75 V ≤ V ≤ 40 V, 0.2 A ≤ I

≤ 1.0 A)

V

out

in

Load

T = 25°C

T = −40 to +125°C

J

3.168

3.135

3.3

−

3.432

3.465

J

Efficiency (V = 12 V, I

= 1.0 A)

η

−

75

−

%

in

Load

LM2575−5 ([Note 1] Test Circuit Figure 14)

Output Voltage (V = 12 V, I = 0.2 A, T = 25°C)

V

out

4.9

5.0

5.1

V

in

Load

J

Output Voltage (8.0 V ≤ V ≤ 40 V, 0.2 A ≤ I

≤ 1.0 A)

V

out

in

Load

T = 25°C

J

4.8

5.0

5.2

T = −40 to +125°C

J

4.75

−

5.25

Efficiency (V = 12 V, I

= 1.0 A)

η

−

77

−

%

in

Load

LM2575−12 (Note 1 Test Circuit Figure 14)

Output Voltage (V = 25 V, I = 0.2 A, T = 25°C)

V

out

11.76

12

12.24

V

in

Load

J

Output Voltage (15 V ≤ V ≤ 40 V, 0.2 A ≤ I

≤ 1.0 A)

V

out

in

Load

T = 25°C

T = −40 to +125°C

J

11.52

11.4

12

−

12.48

12.6

J

Efficiency (V = 15V, I

= 1.0 A)

η

−

88

−

%

in

Load

LM2575−15 (Note 1 Test Circuit Figure 14)

Output Voltage (V = 30 V, I = 0.2 A, T = 25°C)

V

out

14.7

15

15.3

V

in

Load

J

Output Voltage (18 V ≤ V ≤ 40 V, 0.2 A ≤ I

≤ 1.0 A)

V

out

in

Load

T = 25°C

J

14.4

15

15.6

T = −40 to +125°C

J

14.25

−

15.75

Efficiency (V = 18 V, I

= 1.0 A)

η

−

88

−

%

in

Load

LM2575 ADJUSTABLE VERSION (Note 1 Test Circuit Figure 14)

Feedback Voltage (V = 12 V, I = 0.2 A, V = 5.0 V, T = 25°C)

V

1.217

1.23

1.243

V

in

Load

out

J

FB

Feedback Voltage (8.0 V ≤ V ≤ 40 V, 0.2 A ≤ I

≤ 1.0 A, V = 5.0 V)

V

FB

in

Load

out

T = 25°C

T = −40 to +125°C

J

1.193

1.18

1.23

−

1.267

1.28

J

Efficiency (V = 12 V, I

= 1.0 A, V = 5.0 V)

η

−

77

−

%

in

Load

out

1. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.

When the LM2575 is used as shown in the Figure 14 test circuit, system performance will be as shown in system parameters section.

2. Tested junction temperature range for the LM2575 and the NCV2575:

T

low

= −40°C

T

high

= +125°C

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3

LM2575, NCV2575

DEVICE PARAMETERS

ELECTRICAL CHARACTERISTICS (Unless otherwise specified, V = 12 V for the 3.3 V, 5.0 V, and Adjustable version, V = 25 V

in

for the 12 V version, and V = 30 V for the 15 V version. I

= 200 mA. For typical values T = 25°C, for min/max values T is the

in

Load

J

operating junction temperature range that applies [Note 2], unless otherwise noted.)

Characteristics Symbol

ALL OUTPUT VOLTAGE VERSIONS

Feedback Bias Current (V = 5.0 V Adjustable Version Only)

Min

Typ

Max

Unit

I

b

nA

out

T = 25°C

T = −40 to +125°C

J

−

25

−

100

200

J

Oscillator Frequency Note 3

f

kHz

V

osc

T = 25°C

−

47

42

52

−

58

63

J

T = 0 to +125°C

J

T = −40 to +125°C

J

Saturation Voltage (I = 1.0 A Note 4)

V

sat

out

T = 25°C

T = −40 to +125°C

J

−

1.0

−

1.2

1.3

J

Max Duty Cycle (“on”) Note 5

DC

94

98

−

%

A

Current Limit (Peak Current Notes 4 and 3)

I

CL

T = 25°C

T = −40 to +125°C

J

1.7

1.4

2.3

−

3.0

3.2

J

Output Leakage Current Notes 6 and 7, T = 25°C

Output = 0 V

Output = −1.0 V

I

mA

V

J

L

−

0.8

6.0

2.0

20

Quiescent Current Note 6

I

Q

T = 25°C

−

5.0

−

9.0

11

J

T = −40 to +125°C

J

Standby Quiescent Current (ON/OFF Pin = 5.0 V (“off”))

I

stby

T = 25°C

15

−

80

−

200

400

J

T = −40 to +125°C

J

ON/OFF Pin Logic Input Level (Test Circuit Figure 14)

V

out

= 0 V

V

IH

T = 25°C

T = −40 to +125°C

J

2.2

2.4

1.4

−

J

V

out

= Nominal Output Voltage

V

IL

T = 25°C

T = −40 to +125°C

J

−

1.2

−

1.0

0.8

J

ON/OFF Pin Input Current (Test Circuit Figure 14)

mA

ON/OFF Pin = 5.0 V (“off”), T = 25°C

I

−

15

0

30

5.0

J

IH

ON/OFF Pin = 0 V (“on”), T = 25°C

J

IL

3. 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 dissipation of the IC by

lowering the minimum duty cycle from 5% down to approximately 2%.

4. Output (Pin 2) sourcing current. No diode, inductor or capacitor connected to output pin.

5. Feedback (Pin 4) removed from output and connected to 0 V.

6. Feedback (Pin 4) removed from output and connected to +12 V for the Adjustable, 3.3 V, and 5.0 V versions, and +25 V for the 12 V and

15 V versions, to force the output transistor “off”.

7. V = 40 V.

in

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4

LM2575, NCV2575

TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 14)

0.6

0.4

1.0

V = 20 V

in

I

= 200 mA

Load

I

= 200 mA

Normalized at

Load

T = 25°C

J

0.8

0.6

0.4

0.2

0

T = 25°C

J

0.2

3.3 V, 5.0 V and Adj

0

-0.2

-0.4

-0.6

12 V and 15 V

-0.2

-50

-25

0

25

50

75

100

125

0

5.0

10

15

20

25

30

35

40

T , JUNCTION TEMPERATURE (°C)

J

V , INPUT VOLTAGE (V)

in

Figure 2. Normalized Output Voltage

Figure 3. Line Regulation

1.2

1.1

1.0

0.9

0.8

0.7

3.0

2.5

2.0

1.5

-40°C

25°C

1.0

0.5

0

0.6

0.5

0.4

125°C

V = 25 V

in

0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

SWITCH CURRENT (A)

-50

-25

0

25

50

75

100

125

T , JUNCTION TEMPERATURE (°C)

J

Figure 4. Switch Saturation Voltage

Figure 5. Current Limit

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

20

18

16

14

12

V

= 5.0 V

DV = 5%

out

Measured at

Ground Pin

T = 25°C

J

R

ind

= 0.2 W

I

= 1.0 A

Load

I

= 1.0 A

Load

10

8.0

6.0

4.0

= 200 mA

Load

I

= 200 mA

Load

-50

-25

0

25

50

75

100

125

0

5.0

10

15

20

25

30

35

40

T , JUNCTION TEMPERATURE (°C)

J

V , INPUT VOLTAGE (V)

in

Figure 6. Dropout Voltage

Figure 7. Quiescent Current

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5

LM2575, NCV2575

120

100

80

60

40

20

0

120

T = 25°C

V = 12 V

in

J

V

= 5.0 V

ON/OFF

100

80

60

40

20

0

5.0

10

15

20

25

30

35

40

-50

-25

0

25

50

75

100

125

V , INPUT VOLTAGE (V)

in

T , JUNCTION TEMPERATURE (°C)

J

Figure 8. Standby Quiescent Current

Figure 9. Standby Quiescent Current

2.0

0

40

20

Adjustable

Version Only

V = 12 V

in

Normalized at 25°C

-2.0

-4.0

-6.0

-8.0

-10

0

-20

-40

-50

-25

0

25

50

75

100

125

-50

-25

0

25

50

75

100

125

T , JUNCTION TEMPERATURE (°C)

J

T , JUNCTION TEMPERATURE (°C)

J

Figure 10. Oscillator Frequency

Figure 11. Feedback Pin Current

10 V

0

100

0

OUTPUT

VOLTAGE

(PIN 2)

OUTPUT

CURRENT

(PIN 2)

1.0 A

-100

0

1.0 A

0.5 A

1.0

0.5

0

INDUCTOR

CURRENT

OUTPUT

RIPPLE

VOLTAGE

20 mV

/DIV

5.0 ms/DIV

100 ms/DIV

Figure 12. Switching Waveforms

Figure 13. Load Transient Response

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6

LM2575, NCV2575

5.0 Output Voltage Versions

Feedback

4

V

in

V

out

L1

330 mH

LM2575−5

Regulated

Output

+

1

Output

2

ON/OFF

3

GND

5

V

in

Unregulated

DC Input

8.0 V - 40 V

C

out

330 mF

/16 V

in

100 mF/50 V

D1

1N5819

Load

-

Adjustable Output Voltage Versions

Feedback

4

V

in

V

LM2575

Adjustable

out

L1

330 mH

Regulated

Output

+

1

Output

2

ON/OFF

3

GND

5

Unregulated

DC Input

8.0 V - 40 V

R2

R1

C

out

330 mF

/16 V

in

100 mF/50 V

D1

1N5819

Load

-

R2

Ǔ

R1

ǒ_{1 )ꢀ}

V

+ V

out

refꢀ

V

out

R2 + R1

ǒ

ꢀꢀ1

Ǔ

ref

Where V = 1.23 V, R1

ref

between 1.0 kW and 5.0 kW

Figure 14. Typical Test Circuit

PCB LAYOUT GUIDELINES

As in any switching regulator, the layout of the printed

circuit board is very important. Rapidly switching currents

associated with wiring inductance, stray capacitance and

parasitic inductance of the printed circuit board traces can

generate voltage transients which can generate

electromagnetic interferences (EMI) and affect the desired

operation. As indicated in the Figure 14, to minimize

inductance and ground loops, the length of the leads

indicated by heavy lines should be kept as short as possible.

For best results, single−point grounding (as indicated) or

ground plane construction should be used.

On the other hand, the PCB area connected to the Pin 2

(emitter of the internal switch) of the LM2575 should be

kept to a minimum in order to minimize coupling to sensitive

circuitry.

Another sensitive part of the circuit is the feedback. It is

important to keep the sensitive feedback wiring short. To

assure this, physically locate the programming resistors near

to the regulator, when using the adjustable version of the

LM2575 regulator.

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7

LM2575, NCV2575

PIN FUNCTION DESCRIPTION

Symbol

Description (Refer to Figure 1)

1

V

in

This pin is the positive input supply for the LM2575 step−down switching regulator. In order to minimize

voltage transients and to supply the switching currents needed by the regulator, a suitable input bypass

capacitor must be present (C in Figure 1).

in

2

Output

This is the emitter of the internal switch. The saturation voltage V of this output switch is typically 1.0 V.

sat

It should be kept in mind that the PCB area connected to this pin should be kept to a minimum in order to

minimize coupling to sensitive circuitry.

3

4

GND

Circuit ground pin. See the information about the printed circuit board layout.

Feedback

This pin senses regulated output voltage to complete the feedback loop. The signal is divided by the

internal resistor divider network R2, R1 and applied to the non−inverting input of the internal error amplifier.

In the Adjustable version of the LM2575 switching regulator this pin is the direct input of the error amplifier

and the resistor network R2, R1 is connected externally to allow programming of the output voltage.

5

ON/OFF

It allows the switching regulator circuit to be shut down using logic level signals, thus dropping the total

input supply current to approximately 80 mA. The input threshold voltage is typically 1.4 V. Applying a

voltage above this value (up to +V ) shuts the regulator off. If the voltage applied to this pin is lower than

in

1.4 V or if this pin is connected to ground, the regulator will be in the “on” condition.

DESIGN PROCEDURE

Buck Converter Basics

current loop. This removes the stored energy from the

The LM2575 is a “Buck” or Step−Down Converter which

is the most elementary forward−mode converter. Its basic

schematic can be seen in Figure 15.

inductor.

The inductor current during this time is:

The operation of this regulator topology has two distinct

time periods. The first one occurs when the series switch is

on, the input voltage is connected to the input of the inductor.

The output of the inductor is the output voltage, and the

rectifier (or catch diode) is reverse biased. During this

period, since there is a constant voltage source connected

across the inductor, the inductor current begins to linearly

ramp upwards, as described by the following equation:

ǒ_{Vout D}Ǔ_toff

V

I

+

L(off)

L

This period ends when the power switch is once again

turned on. Regulation of the converter is accomplished by

varying the duty cycle of the power switch. It is possible to

describe the duty cycle as follows:

t

on

T

d +

, where T is the period of switching.

ǒ_V_inǓ_ton

V

out

For the buck converter with ideal components, the duty

cycle can also be described as:

I

+

L(on)

L

During this “on” period, energy is stored within the core

material in the form of magnetic flux. If the inductor is

properly designed, there is sufficient energy stored to carry

the requirements of the load during the “off” period.

V

out

d +

V

in

Figure 16 shows the buck converter idealized waveforms

of the catch diode voltage and the inductor current.

Power

Switch

L

V

out

C

out

D1

R

Load

V

in

Figure 15. Basic Buck Converter

The next period is the “off” period of the power switch.

When the power switch turns off, the voltage across the

inductor reverses its polarity and is clamped at one diode

voltage drop below ground by catch dioded. Current now

flows through the catch diode thus maintaining the load

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8

LM2575, NCV2575

V

on(SW)

Power

Switch

Off

Power

Switch

Off

Power

Switch

On

Power

Switch

On

Time

V (FWD)

D

I

pk

I (AV)

Load

I

min

Power

Switch

Power

Switch

Diode

Time

Figure 16. Buck Converter Idealized Waveforms

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9

LM2575, NCV2575

Procedure (Fixed Output Voltage Version) In order to simplify the switching regulator design, a step−by−step design

procedure and example is provided.

Procedure

Example

Given Parameters:

= Regulated Output Voltage (3.3 V, 5.0 V, 12 V or 15 V)

Given Parameters:

= 5.0 V

V

out

V

out

V

= Maximum DC Input Voltage

V

= 20 V

in(max)

I

= Maximum Load Current

I

= 0.8 A

Load(max)

1. Controller IC Selection

According to the required input voltage, output voltage and

current, select the appropriate type of the controller IC output

voltage version.

According to the required input voltage, output voltage,

current polarity and current value, use the LM2575−5

controller IC

2. Input Capacitor Selection (C )

in

To prevent large voltage transients from appearing at the input

and for stable operation of the converter, an aluminium or

tantalum electrolytic bypass capacitor is needed between the

A 47 mF, 25 V aluminium electrolytic capacitor located near

to the input and ground pins provides sufficient bypassing.

input pin +V and ground pin GND. This capacitor should be

in

located close to the IC using short leads. This capacitor should

have a low ESR (Equivalent Series Resistance) value.

3. Catch Diode Selection (D1)

A. For this example the current rating of the diode is 1.0 A.

A. Since the diode maximum peak current exceeds the

regulator maximum load current the catch diode current

rating must be at least 1.2 times greater than the maximum

load current. For a robust design the diode should have a

current rating equal to the maximum current limit of the

LM2575 to be able to withstand a continuous output short

B. The reverse voltage rating of the diode should be at least

1.25 times the maximum input voltage.

B. Use a 30 V 1N5818 Schottky diode, or any of the

suggested fast recovery diodes shown in the Table 4.

4. Inductor Selection (L1)

A. According to the required working conditions, select the

correct inductor value using the selection guide from

Figures 17 to 21.

A. Use the inductor selection guide shown in Figures 17

to 21.

B. From the appropriate inductor selection guide, identify the

inductance region intersected by the Maximum Input

Voltage line and the Maximum Load Current line. Each

region is identified by an inductance value and an inductor

code.

B. From the selection guide, the inductance area intersected

by the 20 V line and 0.8 A line is L330.

C. Select an appropriate inductor from the several different

manufacturers part numbers listed in Table 1 or Table 2.

When using Table 2 for selecting the right inductor the

designer must realize that the inductor current rating must

be higher than the maximum peak current flowing through

the inductor. This maximum peak current can be calculated

as follows:

C. Inductor value required is 330 mH. From the Table 1 or

Table 2, choose an inductor from any of the listed

manufacturers.

ǒ_VinǓ _ton

V

out

p(max) ^{+ I}

I

)

Load(max)

2L

where t is the “on” time of the power switch and

on

V

out

1

osc

t

+

x

on

V

f

in

For additional information about the inductor, see the

inductor section in the “External Components” section of

this data sheet.

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10

LM2575, NCV2575

Procedure (Fixed Output Voltage Version) (continued)In order to simplify the switching regulator design, a step−by−step design

procedure and example is provided.

Procedure

5. Output Capacitor Selection (C

Example

5. Output Capacitor Selection (C

)

out

)

out

A. Since the LM2575 is a forward−mode switching regulator

with voltage mode control, its open loop 2−pole−2−zero

frequency characteristic has the dominant pole−pair

determined by the output capacitor and inductor values. For

stable operation and an acceptable ripple voltage,

(approximately 1% of the output voltage) a value between

100 mF and 470 mF is recommended.

A. C = 100 mF to 470 mF standard aluminium electrolytic.

out

B. Due to the fact that the higher voltage electrolytic capacitors

generally have lower ESR (Equivalent Series Resistance)

numbers, the output capacitor’s voltage rating should be at

least 1.5 times greater than the output voltage. For a 5.0 V

regulator, a rating at least 8V is appropriate, and a 10 V or

16 V rating is recommended.

B. Capacitor voltage rating = 16 V.

Procedure (Adjustable Output Version: LM2575−Adj)

Procedure

Example

Given Parameters:

V

out

= Regulated Output Voltage

V

out

= 8.0 V

V

= Maximum DC Input Voltage

V

= 12 V

in(max)

I

= Maximum Load Current

I

= 1.0 A

Load(max)

1. Programming Output Voltage

1. Programming Output Voltage (selecting R1 and R2)

To select the right programming resistor R1 and R2 value (see

Figure 14) use the following formula:

Select R1 and R2:

R2

R1

_{+ 1.23}ǒ_{1 )}Ǔ_{Select R1 = 1.8 kW}

V

out

R2

R1

ǒ_{1 )}Ǔ _{where V}

V

+ V

= 1.23 V

ref

out

ref

V

8.0 V

_{+ 1.8 k}ǒ _{* 1}Ǔ

1.23 V

out

_{R2 + R1}ǒ Ǔ

* 1

Resistor R1 can be between 1.0 k and 5.0 kW. (For best

temperature coefficient and stability with time, use 1% metal

film resistors).

V

ref

R2 = 9.91 kW, choose a 9.88 k metal film resistor.

V

out

_{R2 + R1}ǒ Ǔ

1

V

ref

2. Input Capacitor Selection (C )

in

To prevent large voltage transients from appearing at the input

and for stable operation of the converter, an aluminium or

tantalum electrolytic bypass capacitor is needed between the

A 100 mF aluminium electrolytic capacitor located near the

input and ground pin provides sufficient bypassing.

input pin +V and ground pin GND This capacitor should be

in

located close to the IC using short leads. This capacitor should

have a low ESR (Equivalent Series Resistance) value.

For additional information see input capacitor section in the

“External Components” section of this data sheet.

3. Catch Diode Selection (D1)

A. Since the diode maximum peak current exceeds the

regulator maximum load current the catch diode current

rating must be at least 1.2 times greater than the maximum

load current. For a robust design, the diode should have a

current rating equal to the maximum current limit of the

LM2575 to be able to withstand a continuous output short.

B. The reverse voltage rating of the diode should be at least

1.25 times the maximum input voltage.

A. For this example, a 3.0 A current rating is adequate.

B. Use a 20 V 1N5820 or MBR320 Schottky diode or any

suggested fast recovery diode in the Table 4.

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11

LM2575, NCV2575

Procedure (Adjustable Output Version: LM2575−Adj) (continued)

Procedure

Example

A. Calculate E x T [V x ms] constant:

8.0 1000

4. Inductor Selection (L1)

A. Use the following formula to calculate the inductor Volt x

microsecond [V x ms] constant:

_{E x T +}ǒ_{V out}Ǔ ^Vout

6

10

ǒ

Ǔ

E x T + 12 8.0 x

x

+ 51 [V x ms]

V

x

[V x ms]

12

52

in

V

F[Hz]

on

B. Match the calculated E x T value with the corresponding

number on the vertical axis of the Inductor Value Selection

Guide shown in Figure 21. This E x T constant is a measure

of the energy handling capability of an inductor and is

dependent upon the type of core, the core area, the number

of turns, and the duty cycle.

B. E x T = 51 [V x ms]

C. Next step is to identify the inductance region intersected by

the E x T value and the maximum load current value on the

horizontal axis shown in Figure 21.

C. I

= 1.0 A

Load(max)

Inductance Region = L220

D. From the inductor code, identify the inductor value. Then

select an appropriate inductor from the Table 1 or Table 2.

The inductor chosen must be rated for a switching

D. Proper inductor value = 220 mH

Choose the inductor from the Table 1 or Table 2.

frequency of 52 kHz and for a current rating of 1.15 x I

The inductor current rating can also be determined by

.

Ioad

^{calculating the inductor peak cur}ǒ^re_V^nt:Ǔ_t

V

on

out

in

p(max) ^{+ I}

I

)

Load(max)

2L

where t is the “on” time of the power switch and

on

V

out

1

osc

t

+

x

on

V

f

in

For additional information about the inductor, see the

inductor section in the “External Components” section of

this data sheet.

5. Output Capacitor Selection (C

)

out

5. Output Capacitor Selection (C

)

out

A. Since the LM2575 is a forward−mode switching regulator

with voltage mode control, its open loop 2−pole−2−zero

frequency characteristic has the dominant pole−pair

determined by the output capacitor and inductor values.

A.

12

C

w 7.785

+ 53 μF

out

8.220

To achieve an acceptable ripple voltage, select

= 100 mF electrolytic capacitor.

C

out

For stable operation, the capacitor must satisfy the

following requirement:

V

in(max)

x L [μH]

C

w 7.785

[μF]

out

V

out

B. Capacitor values between 10 mF and 2000 mF will satisfy

the loop requirements for stable operation. To achieve an

acceptable output ripple voltage and transient response, the

output capacitor may need to be several times larger than

the above formula yields.

C. Due to the fact that the higher voltage electrolytic capacitors

generally have lower ESR (Equivalent Series Resistance)

numbers, the output capacitor’s voltage rating should be at

least 1.5 times greater than the output voltage. For a 5.0 V

regulator, a rating of at least 8V is appropriate, and a 10 V

or 16 V rating is recommended.

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12

LM2575, NCV2575

INDUCTOR VALUE SELECTION GUIDE

60

20

60

H1000

H1500

H1000

40

25

20

L680

15

10

L680

L470

15

12

8.0

7.0

L470

L330

L220

10

L330

L150

6.0

9.0

L220

8.0

L100

L150

5.0

0.2

7.0

0.2

0.3

0.4

0.5

0.6

0.8

1.0

0.3

0.4

0.5

0.6 0.7 0.8 0.9 1.0

I , MAXIMUM LOAD CURRENT (A)

L

I , MAXIMUM LOAD CURRENT (A)

L

Figure 17. LM2575−3.3

Figure 18. LM2575−5.0

60

H2200

40

30

40

35

30

H1500

H1000

H1500

H1000

25

H680

25

22

H680

H470

L220

20

18

17

20

19

L680

16

15

L470

0.5

L470

0.5

L330

18

L220

17

0.2

14

0.2

0.3

0.4

0.6 0.7 0.8 0.9 1.0

0.3

0.4

0.6 0.7 0.8 0.9 1.0

I , MAXIMUM LOAD CURRENT (A)

L

I , MAXIMUM LOAD CURRENT (A)

L

Figure 19. LM2575−12

Figure 20. LM2575−15

200

150

125

H2200

H1500

H1000

H680

L220

100

H470

80

70

60

L680

50

L470

40

L330

0.5

30

20

L150

L100

0.2

0.3

0.4

0.6 0.7 0.8 0.9 1.0

I , MAXIMUM LOAD CURRENT (A)

L

Figure 21. LM2575−Adj

NOTE: This Inductor Value Selection Guide is applicable for continuous mode only.

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13

LM2575, NCV2575

Table 1. Inductor Selection Guide

Inductor

Code

Inductor

Value

Pulse Eng

PE−92108

PE−53113

PE−52626

PE−52627

PE−53114

PE−52629

PE−53115

PE−53116

PE−53117

PE−53118

PE−53119

PE−53120

PE−53121

PE−53122

Renco

RL2444

RL1954

RL1953

RL1952

RL1951

RL1950

RL2445

RL2446

RL2447

RL1961

RL1960

RL1959

RL1958

RL2448

AIE

Tech 39

77 308 BV

77 358 BV

77 408 BV

77 458 BV

−

L100

L150

100 mH

150 mH

220 mH

330 mH

470 mH

680 mH

150 mH

220 mH

330 mH

470 mH

680 mH

1000 mH

1500 mH

2200 mH

415−0930

415−0953

415−0922

415−0926

415−0927

415−0928

415−0936

430−0636

430−0635

430−0634

415−0935

415−0934

415−0933

415−0945

L220

L330

L470

L680

77 508 BV

77 368 BV

77 410 BV

77 460 BV

−

H150

H220

H330

H470

H680

H1000

H1500

H2200

77 510 BV

77 558 BV

−

77 610 BV

Table 2. Inductor Selection Guide

Renco

Inductance Current

Schott

Pulse Engineering

Coilcraft

(mH)

(A)

THT

SMT

THT

SMT

THT

SMT

0.32

0.58

0.99

1.78

0.48

0.82

1.47

0.39

0.66

1.20

0.32

0.55

1.00

0.42

0.80

67143940

67143990

67144070

67144140

67143980

67144060

67144130

−

67144310

67144360

67144450

67144520

67144350

67144440

67144510

67144340

67144430

67144500

67144330

67144420

67144490

67144410

67144480

RL−1284−68−43 RL1500−68

PE−53804

PE−53812

PE−53821

PE−53830

PE−53811

PE−53820

PE−53829

PE−53810

PE−53819

PE−53828

PE−53809

PE−53818

PE−53827

PE−53817

PE−53826

PE−53804−S

DO1608−68

RL−5470−6

RL−5471−5

RL−5470−5

RL−5471−4

RL−5470−4

RL−5471−3

RL−5470−3

RL−5471−2

RL−5471−1

RL1500−68

−

PE−53812−S DO3308−683

PE−53821−S DO3316−683

PE−53830−S DO5022P−683

68

RL1500−100

−

PE−53811−S

DO3308−104

PE−53820−S DO3316−104

PE−53829−S DO5022P−104

PE−53810−S DO3308−154

PE−53819−S DO3316−154

PE−53828−S DO5022P−154

PE−53809−S DO3308−224

PE−53818−S DO3316−224

PE−53827−S DO5022P−224

PE−53817−S DO3316−334

PE−53826−S DO5022P−334

100

150

RL1500−150

−

67144050

67144120

67143960

67144040

67144110

67144030

67144100

RL1500−220

−

220

330

RL1500−330

−

NOTE: Table 1 and Table 2 of this Indicator Selection Guide shows some examples of different manufacturer products suitable for design

with the LM2575.

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14

LM2575, NCV2575

Table 3. Example of Several Inductor Manufacturers Phone/Fax Numbers

Phone

Fax

+ 1−619−674−8100

+ 1−619−674−8262

Pulse Engineering Inc.

Pulse Engineering Inc. Europe

Renco Electronics Inc.

AIE Magnetics

Phone

Fax

+ 353 93 24 107

+ 353 93 24 459

Phone

Fax

+ 1−516−645−5828

+ 1−516−586−5562

Phone

Fax

+ 1−813−347−2181

Phone

Fax

+ 1−708−322−2645

+ 1−708−639−1469

Coilcraft Inc.

Phone

Fax

+ 44 1236 730 595

+ 44 1236 730 627

Coilcraft Inc., Europe

Tech 39

Phone

Fax

+ 33 8425 2626

+ 33 8425 2610

Phone

Fax

+ 1−612−475−1173

+ 1−612−475−1786

Schott Corp.

Table 4. Diode Selection Guide gives an overview about both surface−mount and through−hole diodes for an

effective design. Device listed in bold are available from ON Semiconductor.

Schottky

Ultra−Fast Recovery

1.0 A

3.0 A

1.0 A

3.0 A

SMT

THT

SMT

THT

SMT

THT

SMT

THT

V

R

20 V

SK12

1N5817

SR102

SK32

MBRD320

1N5820

MBR320

SR302

30 V

MBRS130LT3

1N5818

SR103

11DQ03

SK33

MBRD330

1N5821

MBR330

SR303

MURS320T3

MURD320

MURS120T3

SK13

MUR120

11DF1

HER102

31DQ03

40 V

50 V

MBRS140T3

SK14

10BQ040

10MQ040

1N5819

SR104

11DQ04

MBRS340T3

MBRD340

30WQ04

SK34

1N5822

MBR340

SR304

10BF10

MUR320

30WF10

MUR420

31DQ04

MBRS150

10BQ050

MBR150

SR105

MBRD350

SK35

MBR350

SR305

31DF1

HER302

11DQ05

30WQ05

11DQ05

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15

LM2575, NCV2575

EXTERNAL COMPONENTS

Input Capacitor (C_in)

The Input Capacitor Should Have a Low ESR

(below 0.05 W), there is a possibility of an unstable feedback

loop, resulting in oscillation at the output. This situation can

occur when a tantalum capacitor, that can have a very low

ESR, is used as the only output capacitor.

For stable operation of the switch mode converter a low

ESR (Equivalent Series Resistance) aluminium or solid

tantalum bypass capacitor is needed between the input pin

and the ground pin to prevent large voltage transients from

appearing at the input. It must be located near the regulator

and use short leads. With most electrolytic capacitors, the

capacitance value decreases and the ESR increases with

lower temperatures. For reliable operation in temperatures

below −25°C larger values of the input capacitor may be

needed. Also paralleling a ceramic or solid tantalum

capacitor will increase the regulator stability at cold

temperatures.

At Low Temperatures, Put in Parallel Aluminium

Electrolytic Capacitors with Tantalum Capacitors

Electrolytic capacitors are not recommended for

temperatures below −25°C. The ESR rises dramatically at

cold temperatures and typically rises 3 times at −25°C and

as much as 10 times at −40°C. Solid tantalum capacitors

have much better ESR spec at cold temperatures and are

recommended for temperatures below −25°C. They can be

also used in parallel with aluminium electrolytics. The value

of the tantalum capacitor should be about 10% or 20% of the

total capacitance. The output capacitor should have at least

50% higher RMS ripple current rating at 52 kHz than the

peak−to−peakinductor ripple current.

RMS Current Rating of C

in

The important parameter of the input capacitor is the RMS

current rating. Capacitors that are physically large and have

large surface area will typically have higher RMS current

ratings. For a given capacitor value, a higher voltage

electrolytic capacitor will be physically larger than a lower

voltage capacitor, and thus be able to dissipate more heat to

the surrounding air, and therefore will have a higher RMS

current rating. The consequence of operating an electrolytic

capacitor above the RMS current rating is a shortened

operating life. In order to assure maximum capacitor

operating lifetime, the capacitor’s RMS ripple current rating

should be:

Catch Diode

Locate the Catch Diode Close to the LM2575

The LM2575 is a step−down buck converter; it requires a

fast diode to provide a return path for the inductor current

when the switch turns off. This diode must be located close

to the LM2575 using short leads and short printed circuit

traces to avoid EMI problems.

Use a Schottky or a Soft Switching

Ultra−Fast Recovery Diode

I_rms> 1.2 x d x I_Load

Since the rectifier diodes are very significant source of

losses within switching power supplies, choosing the

rectifier that best fits into the converter design is an

important process. Schottky diodes provide the best

performance because of their fast switching speed and low

forward voltage drop.

They provide the best efficiency especially in low output

voltage applications (5.0 V and lower). Another choice

could be Fast−Recovery, or Ultra−Fast Recovery diodes. It

has to be noted, that some types of these diodes with an

abrupt turnoff characteristic may cause instability or EMI

troubles.

A fast−recovery diode with soft recovery characteristics

can better fulfill a quality, low noise design requirements.

Table 4 provides a list of suitable diodes for the LM2575

regulator. Standard 50/60 Hz rectifier diodes such as the

1N4001 series or 1N5400 series are NOT suitable.

where d is the duty cycle, for a buck regulator

V

t

on

T

out

d +

|V

+

V

in

|

t

on

T

out

|V | ) V

and d +

+

for a buck*boost regulator.

out

in

Output Capacitor (C_out

)

For low output ripple voltage and good stability, low ESR

output capacitors are recommended. An output capacitor

has two main functions: it filters the output and provides

regulator loop stability. The ESR of the output capacitor and

the peak−to−peak value of the inductor ripple current are the

main factors contributing to the output ripple voltage value.

Standard aluminium electrolytics could be adequate for

some applications but for quality design low ESR types are

recommended.

Inductor

An aluminium electrolytic capacitor’s ESR value is

related to many factors such as the capacitance value, the

voltage rating, the physical size and the type of construction.

In most cases, the higher voltage electrolytic capacitors have

lower ESR value. Often capacitors with much higher

voltage ratings may be needed to provide low ESR values

that are required for low output ripple voltage.

The magnetic components are the cornerstone of all

switching power supply designs. The style of the core and

the winding technique used in the magnetic component’s

design has a great influence on the reliability of the overall

power supply.

Using an improper or poorly designed inductor can cause

high voltage spikes generated by the rate of transitions in

current within the switching power supply, and the

possibility of core saturation can arise during an abnormal

operational mode. Voltage spikes can cause the

semiconductors to enter avalanche breakdown and the part

can instantly fail if enough energy is applied. It can also

The Output Capacitor Requires an ESR Value

That Has an Upper and Lower Limit

As mentioned above, a low ESR value is needed for low

output ripple voltage, typically 1% to 2% of the output

voltage. But if the selected capacitor’s ESR is extremely low

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16

LM2575, NCV2575

cause significant RFI (Radio Frequency Interference) and

the physical volume the inductor must fit within, and the

amount of EMI (Electro−Magnetic Interference) shielding

that the core must provide. The inductor selection guide

covers different styles of inductors, such as pot core, E−core,

toroid and bobbin core, as well as different core materials

such as ferrites and powdered iron from different

manufacturers.

For high quality design regulators the toroid core seems to

be the best choice. Since the magnetic flux is completely

contained within the core, it generates less EMI, reducing

noise problems in sensitive circuits. The least expensive is

the bobbin core type, which consists of wire wound on a

ferrite rod core. This type of inductor generates more EMI

due to the fact that its core is open, and the magnetic flux is

not completely contained within the core.

When multiple switching regulators are located on the

same printed circuit board, open core magnetics can cause

interference between two or more of the regulator circuits,

especially at high currents due to mutual coupling. A toroid,

pot core or E−core (closed magnetic structure) should be

used in such applications.

EMI (Electro−Magnetic Interference) problems.

Continuous and Discontinuous Mode of Operation

The LM2575 step−down converter can operate in both the

continuous and the discontinuous modes of operation. The

regulator works in the continuous mode when loads are

relatively heavy, the current flows through the inductor

continuously and never falls to zero. Under light load

conditions, the circuit will be forced to the discontinuous

mode when inductor current falls to zero for certain period

of time (see Figure 22 and Figure 23). Each mode has

distinctively different operating characteristics, which can

affect the regulator performance and requirements. In many

cases the preferred mode of operation is the continuous

mode. It offers greater output power, lower peak currents in

the switch, inductor and diode, and can have a lower output

ripple voltage. On the other hand it does require larger

inductor values to keep the inductor current flowing

continuously, especially at low output load currents and/or

high input voltages.

To simplify the inductor selection process, an inductor

selection guide for the LM2575 regulator was added to this

data sheet (Figures 17 through 21). This guide assumes that

the regulator is operating in the continuous mode, and

selects an inductor that will allow a peak−to−peak inductor

ripple current to be a certain percentage of the maximum

design load current. This percentage is allowed to change as

different design load currents are selected. For light loads

(less than approximately 200 mA) it may be desirable to

operate the regulator in the discontinuous mode, because the

inductor value and size can be kept relatively low.

Consequently, the percentage of inductor peak−to−peak

current increases. This discontinuous mode of operation is

perfectly acceptable for this type of switching converter.

Any buck regulator will be forced to enter discontinuous

mode if the load current is light enough.

Do Not Operate an Inductor Beyond its

Maximum Rated Current

Exceeding an inductor’s maximum current rating may

cause the inductor to overheat because of the copper wire

losses, or the core may saturate. Core saturation occurs when

the flux density is too high and consequently the cross

sectional area of the core can no longer support additional

lines of magnetic flux.

This causes the permeability of the core to drop, the

inductance value decreases rapidly and the inductor begins

to look mainly resistive. It has only the dc resistance of the

winding. This can cause the switch current to rise very

rapidly and force the LM2575 internal switch into

cycle−by−cycle current limit, thus reducing the dc output

load current. This can also result in overheating of the

inductor and/or the LM2575. Different inductor types have

different saturation characteristics, and this should be kept

in mind when selecting an inductor.

1.0

0

0.1

0

1.0

0

0.1

0

HORIZONTAL TIME BASE: 5.0 ms/DIV

Figure 22. Continuous Mode Switching

Current Waveforms

HORIZONTAL TIME BASE: 5.0 ms/DIV

Figure 23. Discontinuous Mode Switching

Current Waveforms

Selecting the Right Inductor Style

Some important considerations when selecting a core type

are core material, cost, the output power of the power supply,

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17

LM2575, NCV2575

GENERAL RECOMMENDATIONS

Output Voltage Ripple and Transients

Heatsinking and Thermal Considerations

Source of the Output Ripple

The Through−Hole Package TO−220

Since the LM2575 is a switch mode power supply

regulator, its output voltage, if left unfiltered, will contain a

sawtooth ripple voltage at the switching frequency. The

output ripple voltage value ranges from 0.5% to 3% of the

output voltage. It is caused mainly by the inductor sawtooth

ripple current multiplied by the ESR of the output capacitor.

The LM2575 is available in two packages, a 5−pin

TO−220(T, TV) and a 5−pin surface mount D PAK(D2T).

2

There are many applications that require no heatsink to keep

the LM2575 junction temperature within the allowed

operating range. The TO−220 package can be used without

a heatsink for ambient temperatures up to approximately

50°C (depending on the output voltage and load current).

Higher ambient temperatures require some heatsinking,

either to the printed circuit (PC) board or an external

heatsink.

Short Voltage Spikes and How to Reduce Them

The regulator output voltage may also contain short

voltage spikes at the peaks of the sawtooth waveform (see

Figure 24). These voltage spikes are present because of the

fast switching action of the output switch, and the parasitic

inductance of the output filter capacitor. There are some

other important factors such as wiring inductance, stray

capacitance, as well as the scope probe used to evaluate these

transients, all these contribute to the amplitude of these

spikes. To minimize these voltage spikes, low inductance

capacitors should be used, and their lead lengths must be

kept short. The importance of quality printed circuit board

layout design should also be highlighted.

The Surface Mount Package D²PAK and its

Heatsinking

The other type of package, the surface mount D PAK, is

2

designed to be soldered to the copper on the PC board. The

copper and the board are the heatsink for this package and

the other heat producing components, such as the catch

diode and inductor. The PC board copper area that the

2

package is soldered to should be at least 0.4 in (or 100 mm )

2

and ideally should have 2 or more square inches (1300 mm )

of 0.0028 inch copper. Additional increasing of copper area

2

Voltage spikes caused by switching action of the output

switch and the parasitic inductance of the output capacitor

beyond approximately 3.0 in (2000 mm ) will not improve

heat dissipation significantly. If further thermal

improvements are needed, double sided or multilayer PC

boards with large copper areas should be considered.

UNFILTERED

OUTPUT

VOLTAGE

Thermal Analysis and Design

The following procedure must be performed to determine

whether or not a heatsink will be required. First determine:

VERTICAL

RESOLUTION:

20 mV/DIV

1. P

2. T

3. T

maximum regulator power dissipation in

the application.

maximum ambient temperature in the

application.

maximum allowed junction temperature

(125°C for the LM2575). For a conservative

design, the maximum junction temperature

should not exceed 110°C to assure safe

operation. For every additional 10°C

temperature rise that the junction must

withstand, the estimated operating lifetime

of the component is halved.

D(max)

FILTERED

OUTPUT

VOLTAGE

)

A(max

J(max)

HORIZONTAL TIME BASE: 10 ms/DIV

Figure 24. Output Ripple Voltage Waveforms

Minimizing the Output Ripple

In order to minimize the output ripple voltage it is possible

to enlarge the inductance value of the inductor L1 and/or to

use a larger value output capacitor. There is also another way

to smooth the output by means of an additional LC filter

(20 mH, 100 mF), that can be added to the output (see

Figure 33) to further reduce the amount of output ripple and

transients. With such a filter it is possible to reduce the

output ripple voltage transients 10 times or more. Figure 24

shows the difference between filtered and unfiltered output

waveforms of the regulator shown in Figure 33.

4. R

5. R

package thermal resistance junction−case.

package thermal resistance junction−ambient.

qJC

qJA

(Refer to Absolute Maximum Ratings in this data sheet or

and R values).

R

qJC

qJA

The following formula is to calculate the total power

dissipated by the LM2575:

P_D= (V_inx I_Q) + d x I_Loadx V_sat

The upper waveform is from the normal unfiltered output

of the converter, while the lower waveform shows the output

ripple voltage filtered by an additional LC filter.

where d is the duty cycle and for buck converter

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18

LM2575, NCV2575

Unregulated

DC Input

12 V to 25 V

V

Feedback

4

t

on

T

O

d +

+

,

L1

100 mH

+V

in

LM2575−12

Output

1

I

(quiescent current) and V can be found in the

C

Q

sat

in

100 mF

/50 V

2

ON/OFF

LM2575 data sheet,

C

out

1800 mF

/16 V

D1

1N5819

3

GND

5

V

is minimum input voltage applied,

is the regulator output voltage,

is the load current.

in

V

O

I

Load

Regulated

Output

-12 V @ 0.35 A

The dynamic switching losses during turn−on and

turn−off can be neglected if proper type catch diode is used.

Figure 25. Inverting Buck−Boost Regulator Using the

LM2575−12 Develops −12 V @ 0.35 A

Packages Not on a Heatsink (Free−Standing)

For a free−standing application when no heatsink is used,

the junction temperature can be determined by the following

expression:

ADDITIONAL APPLICATIONS

Inverting Regulator

T_J= (R_q_JA) (P_D) + T_A

An inverting buck−boost regulator using the LM2575−12

is shown in Figure 25. This circuit converts a positive input

voltage to a negative output voltage with a common ground

by bootstrapping the regulators ground to the negative

output voltage. By grounding the feedback pin, the regulator

senses the inverted output voltage and regulates it.

In this example the LM2575−12 is used to generate a

−12 V output. The maximum input voltage in this case

cannot exceed +28 V because the maximum voltage

appearing across the regulator is the absolute sum of the

input and output voltages and this must be limited to a

maximum of 40 V.

This circuit configuration is able to deliver approximately

0.35 A to the output when the input voltage is 12 V or higher.

At lighter loads the minimum input voltage required drops

to approximately 4.7 V, because the buck−boost regulator

topology can produce an output voltage that, in its absolute

value, is either greater or less than the input voltage.

Since the switch currents in this buck−boost configuration

are higher than in the standard buck converter topology, the

available output current is lower.

This type of buck−boost inverting regulator can also

require a larger amount of startup input current, even for

light loads. This may overload an input power source with

a current limit less than 1.5 A.

Such an amount of input startup current is needed for at

least 2.0 ms or more. The actual time depends on the output

voltage and size of the output capacitor.

Because of the relatively high startup currents required by

this inverting regulator topology, the use of a delayed startup

or an undervoltage lockout circuit is recommended.

where (R )(P ) represents the junction temperature rise

qJA

D

caused by the dissipated power and T is the maximum

A

ambient temperature.

Packages on a Heatsink

If the actual operating junction temperature is greater than

the selected safe operating junction temperature determined

in step 3, than a heatsink is required. The junction

temperature will be calculated as follows:

T_J= P_D(R_q_JA+ R_q_CS+ R_q_SA) + T_A

where

R

qJC

R

qCS

R

qSA

is the thermal resistance junction−case,

is the thermal resistance case−heatsink,

is the thermal resistance heatsink−ambient.

If the actual operating temperature is greater than the

selected safe operating junction temperature, then a larger

heatsink is required.

Some Aspects That can Influence Thermal Design

It should be noted that the package thermal resistance and

the junction temperature rise numbers are all approximate,

and there are many factors that will affect these numbers,

such as PC board size, shape, thickness, physical position,

location, board temperature, as well as whether the

surrounding air is moving or still.

Other factors are trace width, total printed circuit copper

area, copper thickness, single− or double−sided, multilayer

board, the amount of solder on the board or even color of the

traces.

The size, quantity and spacing of other components on

the board can also influence its effectiveness to dissipate

the heat.

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19

LM2575, NCV2575

Using a delayed startup arrangement, the input capacitor

can charge up to a higher voltage before the switch−mode

regulator begins to operate.

+V

in

+V

in

LM2575−XX

1

The high input current needed for startup is now partially

C

R1

100 mF 47 k

in

supplied by the input capacitor C .

in

5

ON/OFF 3

Shutdown

Input

GND

Design Recommendations:

5.0 V

0

The inverting regulator operates in a different manner

than the buck converter and so a different design procedure

has to be used to select the inductor L1 or the output

Off

R3

470

On

R2

47 k

capacitor C

.

out

-V

out

The output capacitor values must be larger than is

normally required for buck converter designs. Low input

voltages or high output currents require a large value output

capacitor (in the range of thousands of mF).

MOC8101

NOTE: This picture does not show the complete circuit.

The recommended range of inductor values for the

inverting converter design is between 68 mH and 220 mH. To

select an inductor with an appropriate current rating, the

inductor peak current has to be calculated.

The following formula is used to obtain the peak inductor

current:

Figure 27. Inverting Buck−Boost Regulator Shut Down

Circuit Using an Optocoupler

With the inverting configuration, the use of the ON/OFF

pin requires some level shifting techniques. This is caused

by the fact, that the ground pin of the converter IC is no

longer at ground. Now, the ON/OFF pin threshold voltage

(1.4 V approximately) has to be related to the negative

output voltage level. There are many different possible shut

down methods, two of them are shown in Figures 27 and 28.

I

(V ) |V |)

V

x t

on

Load in

O

in

2L

I

[

)

peak

V

1

in

x

|V |

O

1

osc

where t

+

, and f

+ 52 kHz.

osc

on

V

) |V |

f

in

O

Under normal continuous inductor current operating

Shutdown

Input

+V

0

Off

conditions, the worst case occurs when V is minimal.

in

Note that the voltage appearing across the regulator is the

absolute sum of the input and output voltage, and must not

exceed 40 V.

On

R2

5.6 k

+V

in

+V

in

1

Unregulated

DC Input

12 V to 25 V

LM2575−XX

Feedback

C

in

100 mF

+V

L1

100 mH

in

4

Output

LM2575−12

Q1

2N3906

1

C

in

100 mF

/50 V

5

ON/OFF 3 GND

R1

C1

0.1 mF

2

ON/OFF 3 GND

5

C

out

1800 mF

/16 V

D1

1N5819

R1

47 k

12 k

-V

out

R2

47 k

NOTE: This picture does not show the complete circuit.

Regulated

Output

-12 V @ 0.35 A

Figure 28. Inverting Buck−Boost Regulator Shut Down

Circuit Using a PNP Transistor

Figure 26. Inverting Buck−Boost

Regulator with Delayed Startup

Negative Boost Regulator

This example is a variation of the buck−boost topology

and is called a negative boost regulator. This regulator

experiences relatively high switch current, especially at low

input voltages. The internal switch current limiting results in

lower output load current capability.

The circuit in Figure 29 shows the negative boost

configuration. The input voltage in this application ranges

from −5.0 V to −12 V and provides a regulated −12 V output.

It has been already mentioned above, that in some

situations, the delayed startup or the undervoltage lockout

features could be very useful. A delayed startup circuit

applied to a buck−boost converter is shown in Figure 26.

Figure 32 in the “Undervoltage Lockout” section describes

an undervoltage lockout feature for the same converter

topology.

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20

LM2575, NCV2575

If the input voltage is greater than −12 V, the output will rise

above −12 V accordingly, but will not damage the regulator.

cause some problems by coupling the ripple into the

ON/OFF pin, the regulator could be switched periodically

on and off with the line (or double) frequency.

C

out

1000 mF

/16 V

+V

in

4

LM2575−XX

1

+V

in

Feedback

Output

2

LM2575−12

D1

1

C1

0.1 mF

5

ON/OFF 3 GND

C

in

100 mF

/50 V

Regulated

Output

1N5817

3

5

GND

ON/OFF

C

in

100 mF

V

= -12 V

out

R1

47 k

R2

47 k

Load Current from

200 mA for V = -5.2 V

to 500 mA for V = -7.0 V

L1

in

150 mH

Unregulated

DC Input

-V = -5.0 V to -12 V

NOTE: This picture does not show the complete circuit.

in

Figure 30. Delayed Startup Circuitry

Figure 29. Negative Boost Regulator

Design Recommendations:

The same design rules as for the previous inverting

buck−boost converter can be applied. The output capacitor

Undervoltage Lockout

Some applications require the regulator to remain off until

the input voltage reaches a certain threshold level. Figure 31

shows an undervoltage lockout circuit applied to a buck

regulator. A version of this circuit for buck−boost converter

is shown in Figure 32. Resistor R3 pulls the ON/OFF pin

high and keeps the regulator off until the input voltage

reaches a predetermined threshold level, which is

determined by the following expression:

C

out

must be chosen larger than would be required for a

standard buck converter. Low input voltages or high output

currents require a large value output capacitor (in the range

of thousands of mF). The recommended range of inductor

values for the negative boost regulator is the same as for

inverting converter design.

Another important point is that these negative boost

converters cannot provide current limiting load protection in

the event of a short in the output so some other means, such

as a fuse, may be necessary to provide the load protection.

R2

₎ǒ_{1 )}Ǔ _V

Z1

( )

Q1

V

[ V

th

BE

R1

+V

in

+V

in

LM2575−5.0

Delayed Startup

1

There are some applications, like the inverting regulator

already mentioned above, which require a higher amount of

startup current. In such cases, if the input power source is

limited, this delayed startup feature becomes very useful.

To provide a time delay between the time the input voltage

is applied and the time when the output voltage comes up,

the circuit in Figure 30 can be used. As the input voltage is

applied, the capacitor C1 charges up, and the voltage across

the resistor R2 falls down. When the voltage on the ON/OFF

pin falls below the threshold value 1.4 V, the regulator starts

up. Resistor R1 is included to limit the maximum voltage

applied to the ON/OFF pin, reduces the power supply noise

sensitivity, and also limits the capacitor C1 discharge

current, but its use is not mandatory.

C

in

100 mF

R2

10 k

R3

47 k

5

ON/OFF 3 GND

Z1

1N5242B

Q1

2N3904

R1

10 k

V

th

≈ 13 V

NOTE: This picture does not show the complete circuit.

Figure 31. Undervoltage Lockout Circuit for

Buck Converter

When a high 50 Hz or 60 Hz (100 Hz or 120 Hz

respectively) ripple voltage exists, a long delay time can

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21

LM2575, NCV2575

Adjustable Output, Low−Ripple Power Supply

A 1.0 A output current capability power supply that

features an adjustable output voltage is shown in Figure 33.

This regulator delivers 1.0 A into 1.2 V to 35 V output.

The input voltage ranges from roughly 8.0 V to 40 V. In order

to achieve a 10 or more times reduction of output ripple, an

additional L−C filter is included in this circuit.

+V

in

LM2575−5.0

1

C

in

100 mF

R2

15 k

R3

68 k

5

ON/OFF 3 GND

Z1

1N5242B

V

th

≈ 13 V

Q1

2N3904

R1

15 k

V

out

= -5.0 V

NOTE: This picture does not show the complete circuit.

Figure 32. Undervoltage Lockout Circuit for

Buck−Boost Converter

Feedback

Unregulated

DC Input

+

4

+V

in

L1

150 mH

L2

20 mH

LM2575−Adj

Regulated

Output Voltage

1

Output

2

ON/OFF

1.2 V to 35 V @1.0 A

R2

50 k

3

GND

5

C1

100 mF

C

in

100 mF

/50 V

C

out

2200 mF

D1

1N5819

R1

1.1 k

Optional Output

Ripple Filter

Figure 33. Adjustable Power Supply with Low Ripple Voltage

80

70

3.5

3.0

P

for T = 50°C

A

D(max)

Free Air

Mounted

Vertically

2.0 oz. Copper

L

60

50

40

30

2.5

2.0

1.5

1.0

Minimum

Size Pad

L

R

q

JA

0

5.0

10

15

20

25

30

L, LENGTH OF COPPER (mm)

Figure 34. D²PAK Thermal Resistance and Maximum

Power Dissipation versus P.C.B. Copper Length

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22

LM2575, NCV2575

THE LM2575−5.0 STEP−DOWN VOLTAGE REGULATOR WITH 5.0 V @ 1.0 A OUTPUT POWER

CAPABILITY. TYPICAL APPLICATION WITH THROUGH−HOLE PC BOARD LAYOUT

Feedback

4

+V

in

Unregulated

DC Input

+V = +7.0 V to +40 V

L1

330 mH

LM2575−5.0

1

Output

2

Regulated Output

+V = 5.0 V @ 1.0 A

in

out1

3

GND

5

ON/OFF

C1

100 mF

/50 V

J1

C

out

330 mF

/16 V

D1

1N5819

GND

in

GND

out

C1

C2

D1

L1

−

100 mF, 50 V, Aluminium Electrolytic

330 mF, 16 V, Aluminium Electrolytic

1.0 A, 40 V, Schottky Rectifier, 1N5819

330 mH, Tech 39: 77 458 BV, Toroid Core, Through−Hole, Pin 3 = Start, Pin 7 = Finish

Figure 35. Schematic Diagram of the LM2575−5.0 Step−Down Converter

GND

in

out

U1 LM2575

C1

J1

C2

D1

L1

DC-DC Converter

+V

in

+V

out1

NOTE: Not to scale.

Figure 36. Printed Circuit Board

Component Side

Figure 37. Printed Circuit Board

Copper Side

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23

LM2575, NCV2575

THE LM2575−ADJ STEP−DOWN VOLTAGE REGULATOR WITH 8.0 V @ 1.0 A OUTPUT POWER

CAPABILITY. TYPICAL APPLICATION WITH THROUGH−HOLE PC BOARD LAYOUT

Regulated

Output Unfiltered

V

out1

= 8.0 V @1.0 A

4

Feedback

Unregulated

DC Input

+V

in

L1

330 mH

L2

25 mH

LM2575−Adj

Regulated

Output Filtered

1

+V = +10 V to + 40 V

in

Output

2

ON/OFF

V

out2

= 8.0 V @1.0 A

3

GND

5

R2

10 k

C3

100 mF

/16 V

C1

100 mF

/50 V

C2

330 mF

/16 V

D1

1N5819

R1

1.8 k

R2

R1

₎ǒ_{1 )}

Ǔ

V

+ V

out

ref

V

ref

= 1.23 V

R1 is between 1.0 k and 5.0 k

C1

C2

C3

D1

L1

L2

R1

R2

−

100 mF, 50 V, Aluminium Electrolytic

330 mF, 16 V, Aluminium Electrolytic

100 mF, 16 V, Aluminium Electrolytic

1.0 A, 40 V, Schottky Rectifier, 1N5819

330 mH, Tech 39: 77 458 BV, Toroid Core, Through−Hole, Pin 3 = Start, Pin 7 = Finish

25 mH, TDK: SFT52501, Toroid Core, Through−Hole

−

1.8 k

10 k

Figure 38. Schematic Diagram of the 8.0 V @ 1.0 V Step−Down Converter Using the LM2575−Adj

(An additional LC filter is included to achieve low output ripple voltage)

GND

U1 LM2575

D1

out

in

C3

C1

C2

J1

L1

L2

+V

out2

+V

in

+V

out1

R2 R1

NOTE: Not to scale.

Figure 39. PC Board Component Side

Figure 40. PC Board Copper Side

References

• National Semiconductor LM2575 Data Sheet and Application Note

• National Semiconductor LM2595 Data Sheet and Application Note

• Marty Brown “Practical Switching Power Supply Design”, Academic Press, Inc., San Diego 1990

• Ray Ridley “High Frequency Magnetics Design”, Ridley Engineering, Inc. 1995

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24

LM2575, NCV2575

ORDERING INFORMATION

Nominal

Output Voltage

Operating

Temperature Range

†

Device

LM2575TV−ADJ

LM2575TV−ADJG

Package

Shipping

TO−220 (Vertical Mount)

(Pb−Free)

TO−220 (Straight Lead)

LM2575T−ADJ

50 Units/Rail

TO−220 (Straight Lead)

(Pb−Free)

LM2575T−ADJG

2

D PAK (Surface Mount)

LM2575D2T−ADJ

LM2575D2T−ADJG

2

D PAK (Surface Mount)

1.23 V to 37 V

T = −40° to +125°C

J

(Pb−Free)

2

D PAK (Surface Mount)

LM2575D2T−ADJR4

LM2575D2T−ADJR4G

2

800 Tape & Reel

D PAK (Surface Mount)

(Pb−Free)

2

D PAK (Surface Mount)

NCV2575D2T−ADJG

50 Units/Rail

(Pb−Free)

2

D PAK (Surface Mount)

NCV2575D2T−ADJR4G

800 Tape & Reel

(Pb−Free)

TO−220 (Vertical Mount)

LM2575TV−3.3

TO−220 (Vertical Mount)

(Pb−Free)

LM2575TV−3.3G

TO−220 (Straight Lead)

LM2575T−3.3

50 Units/Rail

800 Tape & Reel

50 Units/Rail

TO−220 (Straight Lead)

(Pb−Free)

LM2575T−3.3G

3.3 V

T = −40° to +125°C

J

2

D PAK (Surface Mount)

LM2575D2T−3.3

2

D PAK (Surface Mount)

LM2575D2T−3.3G

(Pb−Free)

2

D PAK (Surface Mount)

LM2575D2T−3.3R4

LM2575D2T−3.3R4G

2

D PAK (Surface Mount)

(Pb−Free)

TO−220 (Vertical Mount)

LM2575TV−005

TO−220 (Vertical Mount)

(Pb−Free)

LM2575TV−005G

TO−220 (Straight Lead)

LM2575T−005

TO−220 (Straight Lead)

(Pb−Free)

LM2575T−005G

2

D PAK (Surface Mount)

LM2575D2T−005

2

D PAK (Surface Mount)

LM2575D2T−005G

5.0 V

T = −40° to +125°C

J

(Pb−Free)

2

D PAK (Surface Mount)

LM2575D2T−5R4

LM2575D2T−5R4G

2

800 Tape & Reel

D PAK (Surface Mount)

(Pb−Free)

2

D PAK (Surface Mount)

NCV2575D2T−5G

50 Units/Rail

(Pb−Free)

2

D PAK (Surface Mount)

NCV2575D2T−5R4G

800 Tape & Reel

(Pb−Free)

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

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25

LM2575, NCV2575

ORDERING INFORMATION

Nominal

Output Voltage

Operating

Temperature Range

†

Device

LM2575TV−012

LM2575TV−012G

Package

Shipping

TO−220 (Vertical Mount)

(Pb−Free)

LM2575T−012

TO−220 (Straight Lead)

50 Units/Rail

LM2575T−012G

TO−220 (Straight Lead)

(Pb−Free)

2

LM2575D2T−012

D PAK (Surface Mount)

2

LM2575D2T−012G

D PAK (Surface Mount)

12 V

T = −40° to +125°C

J

(Pb−Free)

2

LM2575D2T−12R4

LM2575D2T−12R4G

D PAK (Surface Mount)

2

800 Tape & Reel

D PAK (Surface Mount)

(Pb−Free)

2

NCV2575D2T−12G

D PAK (Surface Mount)

50 Units/Rail

(Pb−Free)

2

NCV2575D2T−12R4G

D PAK (Surface Mount)

800 Tape & Reel

(Pb−Free)

TO−220 (Vertical Mount)

LM2575TV−015

TO−220 (Vertical Mount)

(Pb−Free)

LM2575TV−015G

TO−220 (Straight Lead)

LM2575T−015

50 Units/Rail

TO−220 (Straight Lead)

(Pb−Free)

LM2575T−015G

15 V

T = −40° to +125°C

J

2

D PAK (Surface Mount)

LM2575D2T−015

2

D PAK (Surface Mount)

LM2575D2T−015G

(Pb−Free)

2

LM2575D2T−15R4

LM2575D2T−15R4G

D PAK (Surface Mount)

2

800 Tape & Reel

D PAK (Surface Mount)

(Pb−Free)

†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging

Specifications Brochure, BRD8011/D.

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26

LM2575, NCV2575

MARKING DIAGRAMS

2

TO−220

TV SUFFIX

CASE 314B

TO−220

T SUFFIX

CASE 314D

D PAK

D2T SUFFIX

CASE 936A

D2T SUFFIX

CASE 936A

LM

2575−xxx

AWLYWWG

NC

V2575−xxx

AWLYWWG

LM

2575T−xxx

AWLYWWG

LM

2575T−xxx

AWLYWWG

1

5

1

5

1

5

1

5

xxx = 3.3, 5.0, 12, 15, or ADJ

= Assembly Location

WL = Wafer Lot

= Year

WW = Work Week

= Pb−Free Package

A

Y

G

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27

LM2575, NCV2575

PACKAGE DIMENSIONS

TO−220

TV SUFFIX

CASE 314B−05

ISSUE L

NOTES:

1. DIMENSIONING AND TOLERANCING PER ANSI

Y14.5M, 1982.

2. CONTROLLING DIMENSION: INCH.

3. DIMENSION D DOES NOT INCLUDE

INTERCONNECT BAR (DAMBAR) PROTRUSION.

DIMENSION D INCLUDING PROTRUSION SHALL

NOT EXCEED 0.043 (1.092) MAXIMUM.

C

B

−P−

OPTIONAL

CHAMFER

Q

F

E

A

U

INCHES

DIM MIN MAX

MILLIMETERS

MIN MAX

L

S

V

W

A

B

C

D

E

F

0.572

0.390

0.170

0.025

0.048

0.850

0.067 BSC

0.166 BSC

0.015

0.900

0.320

0.320 BSC

0.140

---

0.468

---

0.090

0.613 14.529 15.570

0.415 9.906 10.541

K

0.180 4.318

0.038 0.635

0.055 1.219

4.572

0.965

1.397

0.935 21.590 23.749

1.702 BSC

4.216 BSC

0.025 0.381 0.635

1.100 22.860 27.940

G

H

J

5X J

K

L

G

0.365 8.128

9.271

3.886

M

0.24 (0.610)

T

H

N

Q

S

U

V

W

8.128 BSC

5X D

0.153 3.556

0.620

0.505 11.888 12.827

0.735 --- 18.669

0.110 2.286 2.794

N

--- 15.748

M

0.10 (0.254)

T P

SEATING

PLANE

−T−

TO−220

T SUFFIX

CASE 314D−04

ISSUE F

NOTES:

SEATING

−T−

PLANE

1. DIMENSIONING AND TOLERANCING PER ANSI

Y14.5M, 1982.

B

C

2. CONTROLLING DIMENSION: INCH.

3. DIMENSION D DOES NOT INCLUDE

INTERCONNECT BAR (DAMBAR) PROTRUSION.

DIMENSION D INCLUDING PROTRUSION SHALL

NOT EXCEED 10.92 (0.043) MAXIMUM.

−Q−

DETAIL A-A

B1

E

A

U

K

INCHES

DIM MIN MAX

MILLIMETERS

MIN MAX

L

A

0.572

0.390

B1 0.375

0.613 14.529 15.570

0.415 9.906 10.541

0.415 9.525 10.541

1 2 3 4 5

B

C

D

E

G

H

J

0.170

0.025

0.048

0.180 4.318

0.038 0.635

0.055 1.219

4.572

0.965

1.397

0.067 BSC

1.702 BSC

0.087

0.015

0.977

0.320

0.140

0.105

0.112 2.210 2.845

0.025 0.381 0.635

1.045 24.810 26.543

0.365 8.128

0.153 3.556

0.117 2.667

J

H

G

K

L

D 5 PL

9.271

3.886

2.972

Q

U

M

0.356 (0.014)

T Q

B

B1

DETAIL A−A

http://onsemi.com

28

LM2575, NCV2575

PACKAGE DIMENSIONS

D²PAK

D2T SUFFIX

CASE 936A−02

ISSUE C

NOTES:

−T−

TERMINAL 6

1. DIMENSIONING AND TOLERANCING PER ANSI

Y14.5M, 1982.

OPTIONAL

CHAMFER

A

E

U

2. CONTROLLING DIMENSION: INCH.

3. TAB CONTOUR OPTIONAL WITHIN DIMENSIONS A

AND K.

S

4. DIMENSIONS U AND V ESTABLISH A MINIMUM

MOUNTING SURFACE FOR TERMINAL 6.

5. DIMENSIONS A AND B DO NOT INCLUDE MOLD

FLASH OR GATE PROTRUSIONS. MOLD FLASH

AND GATE PROTRUSIONS NOT TO EXCEED 0.025

(0.635) MAXIMUM.

K

V

B

H

1

2

3

4 5

M

L

INCHES

MILLIMETERS

DIM

A

B

C

D

E

G

H

K

L

MIN

MAX

0.403

0.368

0.180

0.036

0.055

MIN

9.804

9.042

4.318

0.660

1.143

MAX

10.236

9.347

4.572

0.914

1.397

D

M

P

N

0.386

0.356

0.170

0.026

0.045

0.067 BSC

0.539

0.010 (0.254)

T

G

R

1.702 BSC

0.579 13.691

14.707

0.050 REF

1.270 REF

0.000

0.088

0.018

0.058

0.010

0.102

0.026

0.078

0.000

2.235

0.457

1.473

0.254

2.591

0.660

1.981

C

M

N

P

R

S

U

V

5_ REF

SOLDERING FOOTPRINT*

0.116 REF

0.200 MIN

0.250 MIN

2.946 REF

5.080 MIN

6.350 MIN

8.38

0.33

1.702

0.067

10.66

0.42

1.016

0.04

3.05

0.12

16.02

0.63

mm

inches

ǒ

Ǔ

SCALE 3:1

*For additional information on our Pb−Free strategy and soldering

details, please download the ON Semiconductor Soldering and

Mounting Techniques Reference Manual, SOLDERRM/D.

ON Semiconductor and

are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice

to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability

arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages.

“Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All

operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. SCILLC does not convey any license under its patent rights

nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications

intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should

Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates,

and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death

associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal

Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner.

PUBLICATION ORDERING INFORMATION

LITERATURE FULFILLMENT:

N. American Technical Support: 800−282−9855 Toll Free

USA/Canada

Europe, Middle East and Africa Technical Support:

Phone: 421 33 790 2910

Japan Customer Focus Center

Phone: 81−3−5773−3850

ON Semiconductor Website: www.onsemi.com

Order Literature: http://www.onsemi.com/orderlit

Literature Distribution Center for ON Semiconductor

P.O. Box 5163, Denver, Colorado 80217 USA

Phone: 303−675−2175 or 800−344−3860 Toll Free USA/Canada

Fax: 303−675−2176 or 800−344−3867 Toll Free USA/Canada

Email: orderlit@onsemi.com

For additional information, please contact your local

Sales Representative

LM2575/D

http://onsemi.com

29


型号：	LM2575T-ADJ
厂家：	Rochester Electronics
描述：	3.2 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSFM5, TO-220. 5 PIN 局域网开关
文件：	总30页 (文件大小：1096K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LM2575T-ADJ [ROCHESTER]

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