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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

LM2576xx Series SIMPLE SWITCHER

3-A Step-Down Voltage Regulator

1 Features

1• 3.3-V, 5-V, 12-V, 15-V, and Adjustable Output

Versions

• Adjustable Version Output Voltage Range,1.23 V

to 37 V (57 V for HV Version) ±4% Maximum Over

Line and Load Conditions

• Specified 3-A Output Current

• Wide Input Voltage Range: 40 V Up to 60 V for

HV Version

• 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

2 Applications

• Simple High-Efficiency Step-Down (Buck)

Regulator

• Efficient Preregulator for Linear Regulators

• On-Card Switching Regulators

• Positive-to-Negative Converter (Buck-Boost)

3 Description

The LM2576 series of regulators are monolithic

integrated circuits that provide all the active functions

for a step-down (buck) switching regulator, capable of

driving 3-A load with excellent line and load

regulation. These devices are available in fixed output

voltages of 3.3 V, 5 V, 12 V, 15 V, and an adjustable

output version.

Requiring a minimum number of external

components, these regulators are simple to use and

include fault protection and a fixed-frequency

oscillator.

The LM2576 series offers a high-efficiency

replacement for popular three-terminal linear

regulators. It substantially reduces the size of the

heat sink, and in some cases no heat sink is

required.

A standard series of inductors optimized for use with

the LM2576 are available from several different

manufacturers. This feature greatly simplifies the

design of switch-mode power supplies.

Other features include a ±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.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)

LM2576

LM2576HV TO-220 (5) 10.16 mm × 8.51 mm

DDPAK/TO-263 (5) 10.16 mm × 8.42 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Fixed Output Voltage Version Typical Application Diagram

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

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Product Folder Links: LM2576 LM2576HV

Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description............................................................. 1

4 Revision History..................................................... 2

5 Pin Configuration and Functions......................... 3

6 Specifications......................................................... 4

6.1 Absolute Maximum Ratings ..................................... 4

6.2 ESD Ratings.............................................................. 4

6.3 Recommended Operating Conditions....................... 4

6.4 Thermal Information.................................................. 4

6.5 Electrical Characteristics: 3.3 V................................ 5

6.6 Electrical Characteristics: 5 V................................... 5

6.7 Electrical Characteristics: 12 V................................. 5

6.8 Electrical Characteristics: 15 V................................. 6

6.9 Electrical Characteristics: Adjustable Output

Voltage....................................................................... 6

6.10 Electrical Characteristics: All Output Voltage

Versions..................................................................... 6

6.11 Typical Characteristics............................................ 8

7 Detailed Description............................................ 12

7.1 Overview................................................................. 12

7.2 Functional Block Diagram....................................... 12

7.3 Feature Description................................................. 12

7.4 Device Functional Modes........................................ 14

8 Application and Implementation ........................ 15

8.1 Application Information............................................ 15

8.2 Typical Applications ................................................ 19

9 Power Supply Recommendations...................... 24

10 Layout................................................................... 25

10.1 Layout Guidelines ................................................. 25

10.2 Layout Example .................................................... 26

10.3 Grounding ............................................................. 26

10.4 Heat Sink and Thermal Considerations................ 26

11 Device and Documentation Support................. 28

11.1 Device Support .................................................... 28

11.2 Documentation Suuport ........................................ 29

11.3 Related Links ........................................................ 29

11.4 Community Resources.......................................... 29

11.5 Trademarks........................................................... 29

11.6 Electrostatic Discharge Caution............................ 29

11.7 Glossary................................................................ 29

12 Mechanical, Packaging, and Orderable

Information........................................................... 30

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision C (April 2013) to Revision D Page

• Added ESD Ratings table, Feature Description section, Device Functional Modes,Application and Implementation

section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and

Mechanical, Packaging, and Orderable Information section.................................................................................................. 1

• Moved the thermal resistance data from the Electrical Characteristics: All Output Voltage Versions table to the

Thermal Information table....................................................................................................................................................... 4

Changes from Revision B (April 2013) to Revision C Page

• Changed layout of National Data Sheet to TI format ............................................................................................................. 3

LM2576

LM2576HV

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SNVS107D –JUNE 1999–REVISED MAY 2016

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5 Pin Configuration and Functions

KC Package

5-Pin TO-220

Top View

KTT Package

5-PIN DDPAK/TO-263

Top View DDPAK/TO-263 (S) Package

5-Lead Surface-Mount Package

Top View

(1) I = INPUT, O = OUTPUT

Pin Functions

PIN I/O(1) DESCRIPTION

NO. NAME

1 VIN ISupply input pin to collector pin of high-side transistor. Connect to power supply and input

bypass capacitors CIN. Path from VIN pin to high frequency bypass CIN and GND must be as

short as possible.

2 OUTPUT O Emitter pin of the power transistor. This is a switching node. Attached this pin to an inductor

and the cathode of the external diode.

3 GROUND — Ground pin. Path to CIN must be as short as possible.

4 FEEDBACK I Feedback sense input pin. Connect to the midpoint of feedback divider to set VOUT for ADJ

version or connect this pin directly to the output capacitor for a fixed output version.

5 ON/OFF I Enable input to the voltage regulator. High = OFF and low = ON. Connect to GND to enable

the voltage regulator. Do not leave this pin float.

— TAB — Connected to GND. Attached to heatsink for thermal relief for TO-220 package or put a

copper plane connected to this pin as a thermal relief for DDPAK package.

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.

6 Specifications

6.1 Absolute Maximum Ratings

over the recommended operating junction temperature range of -40°C to 125°C (unless otherwise noted)(1)(2)

MIN MAX UNIT

Maximum supply voltage LM2576 45 V

LM2576HV 63

ON /OFF pin input voltage −0.3V ≤V≤+VIN V

Output voltage to ground (Steady-state) −1 V

Power dissipation Internally Limited

Maximum junction temperature, TJ150 °C

Storage temperature, Tstg −65 150 °C

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

6.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V

6.3 Recommended Operating Conditions

over the recommended operating junction temperature range of -40°C to 125°C (unless otherwise noted)

MIN MAX UNIT

Temperature LM2576, LM2576HV −40 125 °C

Supply voltage LM2576 40 V

LM2576HV 60

(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report, SPRA953 and the Using New Thermal Metrics applications report, SBVA025.

(2) The package thermal impedance is calculated in accordance with JESD 51-7

(3) Thermal Resistances were simulated on a 4-layer, JEDEC board.

6.4 Thermal Information

THERMAL METRIC(1)(2)(3) LM2576, LM2576HV

UNITKTT (TO-263) KC (TO-220)

5 PINS 5 PINS

RθJA Junction-to-ambient thermal resistance 42.6 32.4 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 43.3 41.2 °C/W

RθJB Junction-to-board thermal resistance 22.4 17.6 °C/W

ψJT Junction-to-top characterization parameter 10.7 7.8 °C/W

ψJB Junction-to-board characterization parameter 21.3 17 °C/W

RθJC(bot) Junction-to-case (bottom) thermal resistance 0.4 0.4 °C/W

LM2576

LM2576HV

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SNVS107D –JUNE 1999–REVISED MAY 2016

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

When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical

Characteristics: All Output Voltage Versions.

6.5 Electrical Characteristics: 3.3 V

Specifications are for TJ= 25°C (unless otherwise noted).

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32(1)

VOUT

Output Voltage VIN = 12 V, ILOAD = 0.5 A

Circuit of Figure 26 and Figure 32 3.234 3.3 3.366 V

Output Voltage: LM2576 6 V ≤VIN ≤40 V, 0.5 A ≤

ILOAD ≤3 A

Circuit of Figure 26 and

Figure 32

TJ= 25°C 3.168 3.3 3.432

Applies over full

operating

temperature range 3.135 3.465

Output Voltage: LM2576HV 6 V ≤VIN ≤60 V, 0.5 A ≤

ILOAD ≤3 A

Circuit of Figure 26 and

Figure 32

TJ= 25°C 3.168 3.3 3.45

Applies over full

operating

temperature range 3.135 3.482

ηEfficiency VIN = 12 V, ILOAD = 3 A 75%

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

When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical

Characteristics: All Output Voltage Versions.

6.6 Electrical Characteristics: 5 V

Specifications are for TJ= 25°C for the Figure 26 and Figure 32 (unless otherwise noted).

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32(1)

VOUT Output Voltage VIN = 12 V, ILOAD = 0.5 A

Circuit of Figure 26 and Figure 32 4.9 5 5.1 V

VOUT Output Voltage

LM2576

0.5 A ≤ILOAD ≤3 A,

8 V ≤VIN ≤40 V

Circuit of Figure 26 and

Figure 32

TJ= 25°C 4.8 5 5.2

Applies over full

operating

temperature range 4.75 5.25

VOUT Output Voltage

LM2576HV

0.5 A ≤ILOAD ≤3 A,

8 V ≤VIN ≤60 V

Circuit of Figure 26 and

Figure 32

TJ= 25°C 4.8 5 4.75

Applies over full

operating

temperature range 5.225 5.275

ηEfficiency VIN = 12 V, ILOAD = 3 A 77%

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

When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical

Characteristics: All Output Voltage Versions.

6.7 Electrical Characteristics: 12 V

Specifications are for TJ= 25°C (unless otherwise noted).

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32(1)

VOUT Output Voltage VIN = 25 V, ILOAD = 0.5 A

Circuit of Figure 26 and Figure 32 11.76 12 12.24 V

VOUT Output Voltage

LM2576

0.5 A ≤ILOAD ≤3 A,

15 V ≤VIN ≤40 V

Circuit of Figure 26 and

Figure 32 and

TJ= 25°C 11.52 12 12.48

Applies over full

operating

temperature range 11.4 12.6

VOUT Output Voltage

LM2576HV

0.5 A ≤ILOAD ≤3 A,

15 V ≤VIN ≤60 V

Circuit of Figure 26 and

Figure 32

TJ= 25°C 11.52 12 12.54

Applies over full

operating

temperature range 11.4 12.66

ηEfficiency VIN = 15 V, ILOAD = 3 A 88%

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

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Product Folder Links: LM2576 LM2576HV

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

When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical

Characteristics: All Output Voltage Versions.

6.8 Electrical Characteristics: 15 V

over operating free-air temperature range (unless otherwise noted).

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32(1)

VOUT Output Voltage VIN = 25 V, ILOAD = 0.5 A

Circuit of Figure 26 and Figure 32 14.7 15 15.3 V

VOUT Output Voltage

LM2576

0.5 A ≤ILOAD ≤3 A,

18 V ≤VIN ≤40 V

Circuit of Figure 26 and

Figure 32

TJ= 25°C 14.4 15 15.6

Applies over full

operating

temperature range 14.25 15.75

VOUT Output Voltage

LM2576HV

0.5 A ≤ILOAD ≤3 A,

18 V ≤VIN ≤60 V

Circuit of Figure 26 and

Figure 32

TJ= 25°C 14.4 15 14.25

Applies over full

operating

temperature range 15.68 15.83

ηEfficiency VIN = 18 V, ILOAD = 3 A 88%

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

When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical

Characteristics: All Output Voltage Versions.

6.9 Electrical Characteristics: Adjustable Output Voltage

over operating free-air temperature range (unless otherwise noted).

PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32(1)

VOUT Feedback voltage VIN = 12 V, ILOAD = 0.5 A

VOUT = 5 V,

Circuit of Figure 26 and Figure 32 1.217 1.23 1.243 V

VOUT Feedback Voltage

LM2576

0.5 A ≤ILOAD ≤3 A,

8 V ≤VIN ≤40 V

VOUT = 5 V, Circuit of

Figure 26 and Figure 32

TJ= 25°C 1.193 1.23 1.267

Applies over full

operating

temperature range 1.18 1.28

VOUT Feedback Voltage

LM2576HV

0.5 A ≤ILOAD ≤3 A,

8 V ≤VIN ≤60 V

VOUT = 5 V, Circuit of

Figure 26 and Figure 32

TJ= 25°C 1.193 1.23 1.273

Applies over full

operating

temperature range 1.18 1.286

ηEfficiency VIN = 12 V, ILOAD = 3 A, VOUT = 5 V 77%

(1) All limits specified at room temperature (25°C) unless otherwise noted. All room temperature limits are 100% production tested. All limits

at temperature extremes are specified through correlation using standard Statistical Quality Control (SQC) methods.

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

When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical

Characteristics: All Output Voltage Versions.

(3) The oscillator frequency reduces to approximately 11 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%.

6.10 Electrical Characteristics: All Output Voltage Versions

over operating free-air temperature range (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP(1) MAX UNIT

SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32(2)

IbFeedback Bias Current VOUT = 5 V (Adjustable

Version Only)

TJ= 25°C 100 50

Applies over full

operating

temperature range 500

fOOscillator Frequency(3) TJ= 25°C 47 52 58 kHz

Applies over full operating temperature range 42 63

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LM2576HV

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SNVS107D –JUNE 1999–REVISED MAY 2016

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Electrical Characteristics: All Output Voltage Versions (continued)

over operating free-air temperature range (unless otherwise noted)

PARAMETER TEST CONDITIONS MIN TYP(1) MAX UNIT

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

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

(6) Feedback pin removed from output and connected to +12 V for the Adjustable, 3.3-V, and 5-V versions, and +25 V for the 12-V and 15-

V versions, to force the output transistor OFF.

(7) VIN = 40 V (60 V for high voltage version).

VSAT Saturation Voltage IOUT = 3 A (4)

TJ= 25°C 1.4 1.8

Applies over full

operating

temperature range 2

DC Max Duty Cycle (ON)(5) 93% 98%

ICL Current Limit(4)(3) TJ= 25°C 4.2 5.8 6.9 A

Applies over full operating temperature range 3.5 7.5

ILOutput Leakage Current Output = 0 V

Output = −1 V

Output = −1 V (6)(7) 2 7.5 30 mA

IQQuiescent Current(6) 5 10 mA

ISTBY Standby Quiescent

Current ON /OFF Pin = 5 V (OFF) 50 200 μA

ON /OFF CONTROL TEST CIRCUIT Figure 26 and Figure 32

VIH

ON /OFF Pin

Logic Input Level

VOUT = 0 V TJ= 25°C 2.2 1.4

Applies over full

operating

temperature range 2.4

VIL

VOUT = Nominal Output

Voltage TJ= 25°C 1.2 1

Applies over full

operating

temperature range 0.8

IIH ON /OFF Pin Input

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

IIL ON /OFF Pin = 0 V (ON) 0 10 μA

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

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6.11 Typical Characteristics

(Circuit of Figure 26 and Figure 32)

Figure 1. Normalized Output Voltage Figure 2. Line Regulation

Figure 3. Dropout Voltage Figure 4. Current Limit

Figure 5. Quiescent Current Figure 6. Standby Quiescent Current

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LM2576HV

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Typical Characteristics (continued)

(Circuit of Figure 26 and Figure 32)

Figure 7. Oscillator Frequency Figure 8. Switch Saturation Voltage

Figure 9. Efficiency Figure 10. Minimum Operating Voltage

Figure 11. Quiescent Current vs Duty Cycle Figure 12. Feedback Voltage vs Duty Cycle

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

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Typical Characteristics (continued)

(Circuit of Figure 26 and Figure 32)

Figure 13. Minimum Operating Voltage Figure 14. Quiescent Current vs Duty Cycle

Figure 15. Feedback Voltage vs Duty Cycle Figure 16. Feedback Pin Current

If the DDPAK/TO-263 package is used, the thermal resistance can be

reduced by increasing the PCB copper area thermally connected to

the package. Using 0.5 square inches of copper area, θJA is 50°C/W,

with 1 square inch of copper area, θJA is 37°C/W, and with 1.6 or

more square inches of copper area, θJA is 32°C/W.

Figure 17. Maximum Power Dissipation (DDPAK/TO-263)

VOUT = 15 V

A: Output Pin Voltage, 50 V/div

B: Output Pin Current, 2 A/div

C: Inductor Current, 2 A/div

D: Output Ripple Voltage, 50 mV/div,

AC-Coupled

Horizontal Time Base: 5 μs/div

Figure 18. Switching Waveforms

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LM2576HV

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Typical Characteristics (continued)

(Circuit of Figure 26 and Figure 32)

Figure 19. Load Transient Response

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LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

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7 Detailed Description

7.1 Overview

The LM2576 SIMPLE SWITCHER® regulator is an easy-to-use, non-synchronous step-down DC-DC converter

with a wide input voltage range from 40 V to up to 60 V for a HV version. It is capable of delivering up to 3-A DC

load current with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V,

5 V, 12 V, 15 V, and an adjustable output version. The family requires few external components, and the pin

arrangement was designed for simple, optimum PCB layout.

7.2 Functional Block Diagram

3.3 V R2 = 1.7 k

5 V, R2 = 3.1 k

12 V, R2 = 8.84 k

15 V, R2 = 11.3 k

For ADJ. Version

R1 = Open, R2 = 0 Ω

Patent Pending

7.3 Feature Description

7.3.1 Undervoltage Lockout

In some applications it is desirable to keep the regulator off until the input voltage reaches a certain threshold.

Figure 20 shows an undervoltage lockout circuit that accomplishes this task, while Figure 21 shows the same

circuit applied to a buck-boost configuration. These circuits keep the regulator off until the input voltage reaches

a predetermined level.

VTH ≈VZ1 + 2VBE(Q1) (1)

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Feature Description (continued)

Complete circuit not shown.

Figure 20. Undervoltage Lockout for Buck Circuit

Complete circuit not shown (see Figure 24).

Figure 21. Undervoltage Lockout

for Buck-Boost Circuit

7.3.2 Delayed Start-Up

The ON /OFF pin can be used to provide a delayed start-up feature as shown in Figure 22. With an input voltage

of 20 V and for the part values shown, the circuit provides approximately 10 ms of delay time before the circuit

begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time

constants can cause problems with input voltages that are high in 60-Hz or 120-Hz ripple, by coupling the ripple

into the ON /OFF pin.

7.3.3 Adjustable Output, Low-Ripple Power Supply

Figure 23 shows a 3-A power supply that features an adjustable output voltage. An additional LC filter that

reduces the output ripple by a factor of 10 or more is included in this circuit.

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LM2576HV

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Feature Description (continued)

Complete circuit not shown.

Figure 22. Delayed Start-Up

Figure 23. 1.2-V to 55-V Adjustable 3-A Power Supply With Low Output Ripple

7.4 Device Functional Modes

7.4.1 Shutdown Mode

The ON/OFF pin provides electrical ON and OFF control for the LM2576. When the voltage of this pin is higher

than 1.4 V, the device is in shutdown mode. The typical standby current in this mode is 50 μA.

7.4.2 Active Mode

When the voltage of the ON/OFF pin is below 1.2 V, the device starts switching, and the output voltage rises until

it reaches the normal regulation voltage.

7.4.3 Current Limit

The LM2576 device has current limiting to prevent the switch current from exceeding safe values during an

accidental overload on the output. This current limit value can be found in Electrical Characteristics: All Output

Voltage Versions under the heading of ICL.

The LM2576 uses cycle-by-cycle peak current limit for overload protection. This helps to prevent damage to the

device and external components. The regulator operates in current limit mode whenever the inductor current

exceeds the value of ICL given in Electrical Characteristics: All Output Voltage Versions. This occurs if the load

current is greater than 3 A, or the converter is starting up. Keep in mind that the maximum available load current

depends on the input voltage, output voltage, and inductor value. The regulator also incorporates short-circuit

protection to prevent inductor current run-away. When the voltage on the FB pin (ADJ) falls below about 0.58 V

the switching frequency is dropped to about 11 kHz. This allows the inductor current to ramp down sufficiently

during the switch OFF-time to prevent saturation.

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

8.1.1 Input Capacitor (CIN)

To maintain stability, the regulator input pin must be bypassed with at least a 100-μF electrolytic capacitor. The

capacitor's leads must be kept short, and placed near the regulator.

If the operating temperature range includes temperatures below −25°C, the input capacitor value may need to be

larger. With most electrolytic capacitors, the capacitance value decreases and the ESR increases with lower

temperatures and age. Paralleling a ceramic or solid tantalum capacitor increases the regulator stability at cold

temperatures. For maximum capacitor operating lifetime, the RMS ripple current rating of the capacitor must be

greater than:

(2)

8.1.2 Inductor Selection

All switching regulators have two basic modes of operation: continuous and discontinuous. The difference

between the two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a

period of time in the normal switching cycle. Each mode has distinctively different operating characteristics,

which can affect the regulator performance and requirements.

The LM2576 (or any of the SIMPLE SWITCHER® family can be used for both continuous and discontinuous

modes of operation.

The inductor value selection guides in Figure 27 through Figure 31 are designed for buck regulator designs of

the continuous inductor current type. When using inductor values shown in the inductor selection guide, the

peak-to-peak inductor ripple current is approximately 20% to 30% of the maximum DC current. With relatively

heavy load currents, the circuit operates in the continuous mode (inductor current always flowing), but under light

load conditions, the circuit is forced to the discontinuous mode (inductor current falls to zero for a period of time).

This discontinuous mode of operation is perfectly acceptable. For light loads (less than approximately 300 mA), it

may be desirable to operate the regulator in the discontinuous mode, primarily because of the lower inductor

values required for the discontinuous mode.

The selection guide chooses inductor values suitable for continuous mode operation, but if the inductor value

chosen is prohibitively high, the designer should investigate the possibility of discontinuous operation.

Inductors are available in different styles such as pot core, toriod, E-frame, bobbin core, and so on, as well as

different core materials, such as ferrites and powdered iron. The bobbin core is the least expensive type, and

consists of wire wrapped on a ferrite rod core. This type of construction makes for an inexpensive inductor;

however, because the magnetic flux is not completely contained within the core, the bobbin core generates more

electromagnetic interference (EMI). This EMI can cause problems in sensitive circuits, or can give incorrect

scope readings because of induced voltages in the scope probe.

The inductors listed in the selection chart include ferrite pot core construction for AIE, powdered iron toroid for

Pulse Engineering, and ferrite bobbin core for Renco.

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Application Information (continued)

An inductor must not operate beyond its maximum-rated current because it may saturate. When an inductor

begins to saturate, the inductance decreases rapidly, and the inductor begins to look mainly resistive (the DC

resistance of the winding), causing the switch current to rise very rapidly. Different inductor types have different

saturation characteristics, and this must be considered when selecting an inductor.

The inductor manufacturer's data sheets include current and energy limits to avoid inductor saturation.

8.1.3 Inductor Ripple Current

When the switcher is operating in the continuous mode, the inductor current waveform ranges from a triangular

to a sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage,

the peak-to-peak amplitude of this inductor current waveform remains constant. As the load current rises or falls,

the entire sawtooth current waveform also rises or falls. The average DC value of this waveform is equal to the

DC load current (in the buck regulator configuration).

If the load current drops to a low enough level, the bottom of the sawtooth current waveform reaches zero, and

the switcher changes to a discontinuous mode of operation. This is a perfectly acceptable mode of operation.

Any buck switching regulator (no matter how large the inductor value is) is forced to run discontinuous if the load

current is light enough.

8.1.4 Output Capacitor

An output capacitor is required to filter the output voltage and is needed for loop stability. The capacitor must be

placed near the LM2576 using short PCB traces. Standard aluminum electrolytics are usually adequate, but TI

recommends low ESR types for low output ripple voltage and good stability. The ESR of a capacitor depends on

many factors, including: the value, the voltage rating, physical size, and the type of construction. In general, low

value or low voltage (less than 12 V) electrolytic capacitors usually have higher ESR numbers.

The amount of output ripple voltage is primarily a function of the ESR (Equivalent Series Resistance) of the

output capacitor and the amplitude of the inductor ripple current (ΔIIND). See Inductor Ripple Current.

The lower capacitor values (220 μF to 1000 μF) allows typically 50 mV to 150 mV of output ripple voltage, while

larger-value capacitors reduces the ripple to approximately 20 mV to 50 mV.

Output Ripple Voltage = (ΔIIND) (ESR of COUT) (3)

To further reduce the output ripple voltage, several standard electrolytic capacitors may be paralleled, or a

higher-grade capacitor may be used. Such capacitors are often called high-frequency,low-inductance, or low-

ESR. These reduces the output ripple to 10 mV or 20 mV. However, when operating in the continuous mode,

reducing the ESR below 0.03 Ωcan cause instability in the regulator.

Tantalum capacitors can have a very low ESR, and must be carefully evaluated if it is the only output capacitor.

Because of their good low temperature characteristics, a tantalum can be used in parallel with aluminum

electrolytics, with the tantalum making up 10% or 20% of the total capacitance.

The ripple current rating of the capacitor at 52 kHz should be at least 50% higher than the peak-to-peak inductor

ripple current.

8.1.5 Catch Diode

Buck regulators require a diode to provide a return path for the inductor current when the switch is off. This diode

must be placed close to the LM2576 using short leads and short printed-circuit traces.

Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency,

especially in low output voltage switching regulators (less than 5 V). Fast-recovery, high-efficiency, or ultra-fast

recovery diodes are also suitable, but some types with an abrupt turnoff characteristic may cause instability and

EMI problems. A fast-recovery diode with soft recovery characteristics is a better choice. Standard 60-Hz diodes

(for example, 1N4001 or 1N5400, and so on) are also not suitable. See Table 3 for Schottky and soft fast-

recovery diode selection guide.

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Application Information (continued)

8.1.6 Output Voltage Ripple and Transients

The output voltage of a switching power supply contains a sawtooth ripple voltage at the switcher frequency,

typically about 1% of the output voltage, and may also contain short voltage spikes at the peaks of the sawtooth

waveform.

The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output

capacitor (see Inductor Selection).

The voltage spikes are present because of the fast switching action of the output switch, and the parasitic

inductance of the output filter capacitor. To minimize these voltage spikes, special low inductance capacitors can

be used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope

probe used to evaluate these transients, all contribute to the amplitude of these spikes.

An additional small LC filter (20 μH and 100 μF) can be added to the output (as shown in Figure 23) to further

reduce the amount of output ripple and transients. A 10 × reduction in output ripple voltage and transients is

possible with this filter.

8.1.7 Feedback Connection

The LM2576 (fixed voltage versions) feedback pin must be wired to the output voltage point of the switching

power supply. When using the adjustable version, physically locate both output voltage programming resistors

near the LM2576 to avoid picking up unwanted noise. Avoid using resistors greater than 100 kΩbecause of the

increased chance of noise pickup.

8.1.8 ON /OFF INPUT

For normal operation, the ON /OFF pin must be grounded or driven with a low-level TTL voltage (typically below

1.6 V). To put the regulator into standby mode, drive this pin with a high-level TTL or CMOS signal. The ON

/OFF pin can be safely pulled up to +VIN without a resistor in series with it. The ON /OFF pin must not be left

open.

8.1.9 Inverting Regulator

Figure 24 shows a LM2576-12 in a buck-boost configuration to generate a negative 12-V output from a positive

input voltage. This circuit bootstraps the ground pin of the regulator to the negative output voltage, then by

grounding the feedback pin, the regulator senses the inverted output voltage and regulates it to −12 V.

For an input voltage of 12 V or more, the maximum available output current in this configuration is approximately

700 mA. At lighter loads, the minimum input voltage required drops to approximately 4.7 V.

The switch currents in this buck-boost configuration are higher than in the standard buck-mode design, thus

lowering the available output current. Also, the start-up input current of the buck-boost converter is higher than

the standard buck-mode regulator, and this may overload an input power source with a current limit less than

5 A. Using a delayed turn-on or an undervoltage lockout circuit (described in Negative Boost Regulator) would

allow the input voltage to rise to a high enough level before the switcher would be allowed to turn on.

Because of the structural differences between the buck and the buck-boost regulator topologies, the buck

regulator design procedure section can not be used to select the inductor or the output capacitor. The

recommended range of inductor values for the buck-boost design is between 68 μH and 220 μH, and the output

capacitor values must be larger than what is normally required for buck designs. Low input voltages or high

output currents require a large value output capacitor (in the thousands of micro Farads).

The peak inductor current, which is the same as the peak switch current, can be calculated in Equation 4:

where

• fosc = 52 kHz (4)

Under normal continuous inductor current operating conditions, the minimum VIN represents the worst case.

Select an inductor that is rated for the peak current anticipated.

LM2576-12

3 5

+1N5820

+COUT

2200 PF

Feedback

Output

VIN

CIN

100 PFGND

100 PH

VOUT = -12V

-VIN

-5V to -12V

LOW ESR

ON/OFF

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Application Information (continued)

Figure 24. Inverting Buck-Boost Develops −12 V

Also, the maximum voltage appearing across the regulator is the absolute sum of the input and output voltage.

For a −12-V output, the maximum input voltage for the LM2576 is +28 V, or +48 V for the LM2576HV.

8.1.10 Negative Boost Regulator

Another variation on the buck-boost topology is the negative boost configuration. The circuit in Figure 25 accepts

an input voltage ranging from −5 V to −12 V and provides a regulated −12-V output. Input voltages greater than

−12 V causes the output to rise above −12 V, but does not damage the regulator.

Typical Load Current

400 mA for VIN =−5.2 V

750 mA for VIN =−7 V

Heat sink may be required.

Figure 25. Negative Boost

Because of the boosting function of this type of regulator, the switch current is relatively high, especially at low

input voltages. Output load current limitations are a result of the maximum current rating of the switch. Also,

boost regulators can not provide current-limiting load protection in the event of a shorted load, so some other

means (such as a fuse) may be necessary.

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8.2 Typical Applications

8.2.1 Fixed Output Voltage Version

CIN — 100-μF, 75-V, Aluminum Electrolytic

COUT — 1000-μF, 25-V, Aluminum Electrolytic

D1— Schottky, MBR360

L1— 100 μH, Pulse Eng. PE-92108

R1— 2 k, 0.1%

R2— 6.12 k, 0.1%

Figure 26. Fixed Output Voltage Versions

8.2.1.1 Design Requirements

Table 1 lists the design parameters of this example.

Table 1. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE

Regulated Output Voltage

(3.3 V, 5 V, 12 V, or 15 V), VOUT 5 V

Maximum Input Voltage, VIN(Max) 15 V

Maximum Load Current,

ILOAD(Max) 3 A

8.2.1.2 Detailed Design Procedure

8.2.1.2.1 Inductor Selection (L1)

1. Select the correct Inductor value selection guide from Figure 27,Figure 28,Figure 29,orFigure 30. (Output

voltages of 3.3 V, 5 V, 12 V or 15 V respectively). For other output voltages, see the design procedure for the

adjustable version. Use the selection guide shown in Figure 28.

2. From the inductor value selection guide, identify the inductance region intersected by VIN(Max) and

ILOAD(Max), and note the inductor code for that region. From the selection guide, the inductance area

intersected by the 15-V line and 3-A line is L100.

3. Identify the inductor value from the inductor code, and select an appropriate inductor from the table shown in

Figure 27. Part numbers are listed for three inductor manufacturers. The inductor chosen must be rated for

operation at the LM2576 switching frequency (52 kHz) and for a current rating of 1.15 × ILOAD. For additional

inductor information, see Inductor Selection. Inductor value required is 100 μH from the table in Figure 27.

Choose AIE 415-0930, Pulse Engineering PE92108, or Renco RL2444.

8.2.1.2.2 Output Capacitor Selection (COUT)

1. The value of the output capacitor together with the inductor defines the dominate pole-pair of the switching

regulator loop. For stable operation and an acceptable output ripple voltage, (approximately 1% of the output

voltage) TI recommends a value between 100 μF and 470 μF. We choose COUT = 680-μF to 2000-μF

standard aluminum electrolytic.

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2. The voltage rating of the capacitor must be at least 1.5 times greater than the output voltage. For a 5-V

regulator, a rating of at least 8 V is appropriate, and a 10-V or 15-V rating is recommended. Capacitor

voltage rating = 20 V. Higher voltage electrolytic capacitors generally have lower ESR numbers, and for this

reason it may be necessary to select a capacitor rated for a higher voltage than would normally be needed.

8.2.1.2.3 Catch Diode Selection (D1)

1. The catch-diode current rating must be at least 1.2 times greater than the maximum load current. Also, if the

power supply design must withstand a continuous output short, the diode should have a current rating equal

to the maximum current limit of the LM2576. The most stressful condition for this diode is an overload or

shorted output condition. For this example, a 3-A current rating is adequate.

2. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. Use a 20-V

1N5823 or SR302 Schottky diode, or any of the suggested fast-recovery diodes shown in Table 3.

8.2.1.2.4 Input Capacitor (CIN)

An aluminum or tantalum electrolytic bypass capacitor located close to the regulator is needed for stable

operation. A 100-μF, 25-V aluminum electrolytic capacitor located near the input and ground pins provides

sufficient bypassing.

8.2.1.3 Application Curves

Figure 27. LM2576(HV)-3.3 Figure 28. LM2576(HV)-5.0

Figure 29. LM2576(HV)-12 Figure 30. LM2576(HV)-15

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Figure 31. LM2576(HV)-ADJ

8.2.2 Adjusted Output Voltage Version

where

VREF = 1.23 V, R1 between 1 k and 5 k

Figure 32. Adjustable Output Voltage Version

8.2.2.1 Design Requirements

Table 2 lists the design parameters of this example.

Table 2. Design Parameters

DESIGN PARAMETER EXAMPLE VALUE

Regulated Output Voltage, VOUT 10 V

Maximum Input Voltage, VIN(Max) 25 V

Maximum Load Current,

ILOAD(Max) 3 A

Switching Frequency, F Fixed at 52 kHz

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8.2.2.2 Detailed Design Procedure

8.2.2.2.1 Programming Output Voltage

Select R1 and R2, as shown in Figure 32.

Use Equation 5 to select the appropriate resistor values.

(5)

R1can be between 1k and 5k. (For best temperature coefficient and stability with time, use 1% metal film

resistors)

(6)

(7)

R2= 1 k (8.13 −1) = 7.13 k, closest 1% value is 7.15 k

8.2.2.2.2 Inductor Selection (L1)

1. Calculate the inductor Volt • microsecond constant, E • T (V • μs), from Equation 8:

(8)

Calculate E • T (V • μs)

(9)

2. Use the E • T value from the previous formula and match it with the E • T number on the vertical axis of the

Inductor value selection guide shown in Figure 31.

E•T=115V•μs

3. On the horizontal axis, select the maximum load current.

ILOAD(Max) = 3 A

4. Identify the inductance region intersected by the E • T value and the maximum load current value, and note

the inductor code for that region.

Inductance Region = H150

5. Identify the inductor value from the inductor code, and select an appropriate inductor from the table shown in

Table 4. Part numbers are listed for three inductor manufacturers. The inductor chosen must be rated for

operation at the LM2576 switching frequency (52 kHz) and for a current rating of 1.15 × ILOAD. For additional

inductor information, see Inductor Selection.

Inductor Value = 150 μH

Choose from AIE part #415-0936, Pulse Engineering part #PE-531115, or Renco part #RL2445.

8.2.2.2.3 Output Capacitor Selection (COUT)

1. The value of the output capacitor together with the inductor defines the dominate pole-pair of the switching

regulator loop. For stable operation, the capacitor must satisfy :

yields capacitor values between 10 μF and 2200 μF that satisfies the loop requirements for stable operation.

But to achieve an acceptable output ripple voltage, (approximately 1% of the output voltage) and transient

response, the output capacitor may need to be several times larger than yields.

However, for acceptable output ripple voltage select

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COUT ≥680 μF

COUT = 680-μF electrolytic capacitor

2. The capacitor's voltage rating must be at last 1.5 times greater than the output voltage. For a 10-V regulator,

a rating of at least 15 V or more is recommended. Higher voltage electrolytic capacitors generally have lower

ESR numbers, and for this reason it may be necessary to select a capacitor rate for a higher voltage than

would normally be needed.

8.2.2.2.4 Catch Diode Selection (D1)

1. The catch-diode current rating must be at least 1.2 times greater than the maximum load current. Also, if the

power supply design must withstand a continuous output short, the diode must have a current rating equal to

the maximum current limit of the LM2576. The most stressful condition for this diode is an overload or

shorted output. See Table 3. For this example, a 3.3-A current rating is adequate.

2. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. Use a 30-V

31DQ03 Schottky diode, or any of the suggested fast-recovery diodes in Table 3.

8.2.2.2.5 Input Capacitor (CIN)

An aluminum or tantalum electrolytic bypass capacitor located close to the regulator is needed for stable

operation. A 100-μF aluminum electrolytic capacitor located near the input and ground pins provides sufficient

bypassing.

Table 3. Diode Selection Guide

VRSCHOTTKY FAST RECOVERY

3 A 4 A to 6 A 3 A 4 A to 6 A

20 V 1N5820 1N5823

The following

diodes are all

rated to 100-V

31DF1

HER302

The following

diodes are all

rated to 100-V

50WF10

MUR410

HER602

MBR320P

SR302

30 V

1N5821

50WQ03

1N5824

MBR330

31DQ03

SR303

40 V

1N5822 MBR340

50WQ04

1N5825

MBR340

31DQ04

SR304

50 V MBR350 50WQ0531DQ05

SR305

60 V MBR360 50WR06

50SQ060

DQ06

SR306

(1) Schott Corporation, (612) 475-1173, 1000 Parkers Lake Road, Wayzata, MN 55391.

(2) Pulse Engineering, (619) 674-8100, P.O. Box 12235, San Diego, CA 92112.

(3) Renco Electronics Incorporated, (516) 586-5566, 60 Jeffryn Blvd. East, Deer Park, NY 11729.

Table 4. Inductor Selection by Manufacturer's Part Number

INDUCTOR CODE INDUCTOR VALUE SCHOTT(1) PULSE ENG.(2) RENCO(3)

L47 47 μH 671 26980 PE-53112 RL2442

L68 68 μH 671 26990 PE-92114 RL2443

L100 100 μH 671 27000 PE-92108 RL2444

L150 150 μH 671 27010 PE-53113 RL1954

L220 220 μH 671 27020 PE-52626 RL1953

L330 330 μH 671 27030 PE-52627 RL1952

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Table 4. Inductor Selection by Manufacturer's Part Number (continued)

INDUCTOR CODE INDUCTOR VALUE SCHOTT(1) PULSE ENG.(2) RENCO(3)

L470 470 μH 671 27040 PE-53114 RL1951

L680 680 μH 671 27050 PE-52629 RL1950

H150 150 μH 671 27060 PE-53115 RL2445

H220 220 μH 671 27070 PE-53116 RL2446

H330 330 μH 671 27080 PE-53117 RL2447

H470 470 μH 671 27090 PE-53118 RL1961

H680 680 μH 671 27100 PE-53119 RL1960

H1000 1000 μH 671 27110 PE-53120 RL1959

H1500 1500 μH 671 27120 PE-53121 RL1958

H2200 2200 μH 671 27130 PE-53122 RL2448

9 Power Supply Recommendations

As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring

inductance generate voltage transients which can cause problems. For minimal inductance and ground loops, the

length of the leads indicated by heavy lines should be kept as short as possible. Single-point grounding (as

indicated) or ground plane construction should be used for best results. When using the adjustable version,

physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short.

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10 Layout

10.1 Layout Guidelines

Board layout is critical for the proper operation of switching power supplies. First, the ground plane area must be

sufficient for thermal dissipation purposes. Second, appropriate guidelines must be followed to reduce the effects

of switching noise. Switch mode converters are very fast switching devices. In such cases, the rapid increase of

input current combined with the parasitic trace inductance generates unwanted L di/dt noise spikes. The

magnitude of this noise tends to increase as the output current increases. This noise may turn into

electromagnetic interference (EMI) and can also cause problems in device performance. Therefore, take care in

layout to minimize the effect of this switching noise. The most important layout rule is to keep the AC current

loops as small as possible. Figure 33 shows the current flow in a buck converter. The top schematic shows a

dotted line which represents the current flow during the top-switch ON-state. The middle schematic shows the

current flow during the top-switch OFF-state. The bottom schematic shows the currents referred to as AC

currents. These AC currents are the most critical because they are changing in a very short time period. The

dotted lines of the bottom schematic are the traces to keep as short and wide as possible. This also yields a

small loop area reducing the loop inductance. To avoid functional problems due to layout, review the PCB layout

example. Best results are achieved if the placement of the LM2576 device, the bypass capacitor, the Schottky

diode, RFBB, RFBT, and the inductor are placed as shown in Figure 34.TI also recommends using 2-oz copper

boards or heavier to help thermal dissipation and to reduce the parasitic inductances of board traces. See

application note AN-1229 SIMPLE SWITCHER® PCB Layout Guidelines (SNVA054) for more information.

Figure 33. Current Flow in Buck Application

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10.2 Layout Example

Figure 34. LM2576xx Layout Example

10.3 Grounding

To maintain output voltage stability, the power ground connections must be low-impedance (see Figure 26 and

Figure 32). For the 5-lead TO-220 and DDPAK/TO-263 style package, both the tab and pin 3 are ground and

either connection may be used, as they are both part of the same copper lead frame.

10.4 Heat Sink and Thermal Considerations

In many cases, only a small heat sink is required to keep the LM2576 junction temperature within the allowed

operating range. For each application, to determine whether or not a heat sink is required, the following must be

identified:

1. Maximum ambient temperature (in the application).

2. Maximum regulator power dissipation (in application).

3. Maximum allowed junction temperature (125°C for the LM2576). For a safe, conservative design, a

temperature approximately 15°C cooler than the maximum temperatures must be selected.

4. LM2576 package thermal resistances θJA and θJC.

Total power dissipated by the LM2576 can be estimated in Equation 10:

PD= (VIN)(IQ) + (VO/VIN)(ILOAD)(VSAT)

where

• IQ(quiescent current) and VSAT can be found in Typical Characteristics shown previously,

• VIN is the applied minimum input voltage, VOis the regulated output voltage,

• and ILOAD is the load current. (10)

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Heat Sink and Thermal Considerations (continued)

The dynamic losses during turnon and turnoff are negligible if a Schottky type catch diode is used.

When no heat sink is used, the junction temperature rise can be determined by Equation 11:

ΔTJ= (PD) (θJA) (11)

To arrive at the actual operating junction temperature, add the junction temperature rise to the maximum ambient

temperature.

TJ=ΔTJ+ TA(12)

If the actual operating junction temperature is greater than the selected safe operating junction temperature

determined in step 3, then a heat sink is required.

When using a heat sink, the junction temperature rise can be determined by Equation 13:

ΔTJ= (PD) (θJC +θinterface +θHeat sink) (13)

The operating junction temperature is:

TJ= TA+ΔTJ(14)

As in Equation 14, if the actual operating junction temperature is greater than the selected safe operating

junction temperature, then a larger heat sink is required (one that has a lower thermal resistance).

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11 Device and Documentation Support

11.1 Device Support

11.1.1 Device Nomenclature

11.1.1.1 Definition of Terms

BUCK REGULATOR A switching regulator topology in which a higher voltage is converted to a lower voltage.

Also known as a step-down switching regulator.

BUCK-BOOST REGULATOR A switching regulator topology in which a positive voltage is converted to a

negative voltage without a transformer.

DUTY CYCLE (D) Ratio of the output switch's on-time to the oscillator period.

(15)

CATCH DIODE OR CURRENT STEERING DIODE The diode which provides a return path for the load current

when the LM2576 switch is OFF.

EFFICIENCY (η)The proportion of input power actually delivered to the load.

(16)

CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR) The purely resistive component of a real capacitor's

impedance (see Figure 35). It causes power loss resulting in capacitor heating, which directly

affects the capacitor's operating lifetime. When used as a switching regulator output filter, higher

ESR values result in higher output ripple voltages.

Figure 35. Simple Model of a Real Capacitor

Most standard aluminum electrolytic capacitors in the 100 μF–1000 μF range have 0.5Ωto

0.1ΩESR. Higher-grade capacitors (low-ESR, high-frequency, or low-inductance) in the 100

μF to 1000 μF range generally have ESR of less than 0.15Ω.

EQUIVALENT SERIES INDUCTANCE (ESL) The pure inductance component of a capacitor (see Figure 35).

The amount of inductance is determined to a large extent on the capacitor's construction. In a buck

regulator, this unwanted inductance causes voltage spikes to appear on the output.

OUTPUT RIPPLE VOLTAGE The AC component of the switching regulator's output voltage. It is usually

dominated by the output capacitor's ESR multiplied by the inductor's ripple current (ΔIIND). The

peak-to-peak value of this sawtooth ripple current can be determined by reading Inductor Ripple

Current.

CAPACITOR RIPPLE CURRENT RMS value of the maximum allowable alternating current at which a capacitor

can be operated continuously at a specified temperature.

STANDBY QUIESCENT CURRENT (ISTBY)Supply current required by the LM2576 when in the standby mode

(ON /OFF pin is driven to TTL-high voltage, thus turning the output switch OFF).

INDUCTOR RIPPLE CURRENT (ΔIIND)The peak-to-peak value of the inductor current waveform, typically a

sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous

mode).

CONTINUOUS/DISCONTINUOUS MODE OPERATION Relates to the inductor current. In the continuous mode,

the inductor current is always flowing and never drops to zero, vs. the discontinuous mode, where

the inductor current drops to zero for a period of time in the normal switching cycle.

INDUCTOR SATURATION The condition which exists when an inductor cannot hold any more magnetic flux.

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Device Support (continued)

When an inductor saturates, the inductor appears less inductive and the resistive component

dominates. Inductor current is then limited only by the DC resistance of the wire and the available

source current.

OPERATING VOLT MICROSECOND CONSTANT (E•Top)The product (in VoIt•μs) of the voltage applied to the

inductor and the time the voltage is applied. This E•Top 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.

11.2 Documentation Suuport

11.2.1 Related Documentation

For related documentation, see the following:

AN-1229 SIMPLE SWITCHER® PCB Layout Guidelines (SNVA054)

11.3 Related Links

The table below lists quick access links. Categories include technical documents, support and community

resources, tools and software, and quick access to sample or buy.

Table 5. Related Links

PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL

DOCUMENTS TOOLS &

SOFTWARE SUPPORT &

COMMUNITY

LM2576 Click here Click here Click here Click here Click here

LM2576HV Click here Click here Click here Click here Click here

11.4 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective

contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help

solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

11.5 Trademarks

E2E is a trademark of Texas Instruments.

SIMPLE SWITCHER is a registered trademark of Texas Instruments.

All other trademarks are the property of their respective owners.

11.6 Electrostatic Discharge Caution

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

11.7 Glossary

SLYZ022 —TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

LM2576

LM2576HV

SNVS107D –JUNE 1999–REVISED MAY 2016

www.ti.com

Product Folder Links: LM2576 LM2576HV

12 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

PACKAGE OPTION ADDENDUM

www.ti.com 2-Sep-2017

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2576HVS-12 NRND DDPAK/

TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576

HVS-12 P+

LM2576HVS-12/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-12 P+

LM2576HVS-3.3/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-3.3 P+

LM2576HVS-5.0 NRND DDPAK/

TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576

HVS-5.0 P+

LM2576HVS-5.0/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-5.0 P+

LM2576HVS-ADJ NRND DDPAK/

TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576

HVS-ADJ P+

LM2576HVS-ADJ/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-ADJ P+

LM2576HVSX-12 NRND DDPAK/

TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2576

HVS-12 P+

LM2576HVSX-12/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-12 P+

LM2576HVSX-3.3/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-3.3 P+

LM2576HVSX-5.0 NRND DDPAK/

TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2576

HVS-5.0 P+

LM2576HVSX-5.0/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-5.0 P+

LM2576HVSX-ADJ NRND DDPAK/

TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2576

HVS-ADJ P+

LM2576HVSX-ADJ/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576

HVS-ADJ P+

LM2576HVT-12 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576HVT

-12 P+

LM2576HVT-12/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT

-12 P+

LM2576HVT-12/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT

-12 P+

PACKAGE OPTION ADDENDUM

www.ti.com 2-Sep-2017

Addendum-Page 2

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2576HVT-15/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576HVT

-15 P+

LM2576HVT-15/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT

-15 P+

LM2576HVT-15/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT

-15 P+

LM2576HVT-5.0 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576HVT

-5.0 P+

LM2576HVT-5.0/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576HVT

-5.0 P+

LM2576HVT-5.0/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT

-5.0 P+

LM2576HVT-5.0/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT

-5.0 P+

LM2576HVT-5.0/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT

-5.0 P+

LM2576HVT-ADJ NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576HVT

-ADJ P+

LM2576HVT-ADJ/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576HVT

-ADJ P+

LM2576HVT-ADJ/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT

-ADJ P+

LM2576HVT-ADJ/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT

-ADJ P+

LM2576S-12 NRND DDPAK/

TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576S

-12 P+

LM2576S-12/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-12 P+

LM2576S-3.3/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-3.3 P+

LM2576S-5.0 NRND DDPAK/

TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576S

-5.0 P+

LM2576S-5.0/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-5.0 P+

LM2576S-ADJ/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-ADJ P+

PACKAGE OPTION ADDENDUM

www.ti.com 2-Sep-2017

Addendum-Page 3

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2576SX-3.3/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-3.3 P+

LM2576SX-5.0/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-5.0 P+

LM2576SX-ADJ/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 Pb-Free (RoHS

Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S

-ADJ P+

LM2576T-12 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576T

-12 P+

LM2576T-12/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576T

-12 P+

LM2576T-12/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-12 P+

LM2576T-12/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T

-12 P+

LM2576T-15/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-15 P+

LM2576T-15/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T

-15 P+

LM2576T-3.3/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-3.3 P+

LM2576T-3.3/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T

-3.3 P+

LM2576T-5.0 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576T

-5.0 P+

LM2576T-5.0/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576T

-5.0 P+

LM2576T-5.0/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-5.0 P+

LM2576T-5.0/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-5.0 P+

LM2576T-5.0/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T

-5.0 P+

LM2576T-ADJ NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576T

-ADJ P+

LM2576T-ADJ/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576T

-ADJ P+

PACKAGE OPTION ADDENDUM

www.ti.com 2-Sep-2017

Addendum-Page 4

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead/Ball Finish

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2576T-ADJ/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-ADJ P+

LM2576T-ADJ/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T

-ADJ P+

LM2576T-ADJ/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS

& no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T

-ADJ P+

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.

(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.

(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation

of the previous line and the two combined represent the entire Device Marking for that device.

(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish

value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

PACKAGE OPTION ADDENDUM

www.ti.com 2-Sep-2017

Addendum-Page 5

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type Package

Drawing Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm) B0

(mm) K0

(mm) P1

(mm) W

(mm) Pin1

Quadrant

LM2576HVSX-12 DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576HVSX-12/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576HVSX-3.3/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576HVSX-5.0 DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576HVSX-5.0/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576HVSX-ADJ DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576HVSX-ADJ/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576SX-3.3/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576SX-5.0/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2576SX-ADJ/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

PACKAGE MATERIALS INFORMATION

www.ti.com 18-Jan-2016

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

LM2576HVSX-12 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576HVSX-12/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576HVSX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576HVSX-5.0 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576HVSX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576HVSX-ADJ DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576HVSX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576SX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576SX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2576SX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

PACKAGE MATERIALS INFORMATION

www.ti.com 18-Jan-2016

Pack Materials-Page 2

MECHANICAL DATA

NEB0005B

www.ti.com

PACKAGE OUTLINE

9.25

7.67

6.86

5.69

3.05

2.54

14.73

12.29

5X 1.02

0.64

4X 1.7

8.89

6.86

12.88

10.08

(6.275)

4.83

4.06 1.40

1.14

3.05

2.03

0.61

0.30

-3.963.71

6.8

2X (R1)

OPTIONAL

16.51

MAX

10.67

9.65

(4.25)

4215009/A 01/2017

TO-220 - 16.51 mm max heightKC0005A

TO-220

NOTES:

1. All controlling linear dimensions are in inches. Dimensions in brackets are in millimeters. Any dimension in brackets or parenthesis are for

reference only. Dimensioning and tolerancing per ASME Y14.5M.

2. This drawing is subject to change without notice.

3. Shape may vary per different assembly sites.

0.25 C A B

PIN 1 ID

(OPTIONAL)

OPTIONAL

CHAMFER

SCALE 0.850

NOTE 3

AAAA

www.ti.com

EXAMPLE BOARD LAYOUT

0.07 MAX

ALL AROUND

0.07 MAX

ALL AROUND (1.45)

(2)

(R0.05) TYP

4X (1.45)

4X (2)

5X ( 1.2) (1.7) TYP

(6.8)

FULL R

TYP

TO-220 - 16.51 mm max heightKC0005A

TO-220

4215009/A 01/2017

LAND PATTERN

NON-SOLDER MASK DEFINED

SCALE:12X

PKG

METAL

TYP

SOLDER MASK

OPENING, TYP

MECHANICAL DATA

NDH0005D

www.ti.com

MECHANICAL DATA

KTT0005B

www.ti.com

BOTTOM SIDE OF PACKAGE

TS5B (Rev D)

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Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

Texas Instruments:

LM2576T-15 LM2576T-15/LB03 LM2576T-15/LF03 LM2576T-15/NOPB LM2576T-3.3 LM2576T-3.3/LB03

LM2576T-3.3/LF03 LM2576T-3.3/NOPB LM2576T-5.0 LM2576T-5.0/LB03 LM2576T-5.0/LF02 LM2576T-5.0/LF03

LM2576T-5.0/NOPB LM2576T-ADJ LM2576T-ADJ/LB02 LM2576T-ADJ/LB03 LM2576T-ADJ/LF02 LM2576T-

ADJ/LF03 LM2576T-ADJ/NOPB LM2576S-12 LM2576S-12/NOPB LM2576S-3.3 LM2576S-3.3/NOPB LM2576S-5.0

LM2576S-5.0/NOPB LM2576S-ADJ LM2576S-ADJ/NOPB LM2576SX-3.3 LM2576SX-3.3/NOPB LM2576SX-5.0

LM2576SX-5.0/NOPB LM2576SX-ADJ LM2576SX-ADJ/NOPB LM2576T-12 LM2576T-12/LB03 LM2576T-12/LF03

LM2576T-12/NOPB