on October 20th 10,568

LM2576T Voltage Regulator: Pinout, Circuit Design, and Detailed Datasheet Insights

In modern electronic designs, efficient voltage regulation ensures reliable and stable power supply to various components. The LM2576T series of monolithic integrated regulators is a highly versatile solution for step-down switching applications, commonly known as buck converters. This article explores the key features, practical applications, and design considerations for the LM2576T, offering insights into its implementation and actual performance. Whether used in consumer electronics, power supplies, or industrial automation, this regulator’s efficiency and adaptability make it an invaluable tool for you to optimize power management systems.

Catalog

Overview of LM2576T

The LM2576T series includes monolithic ICs designed to facilitate the creation of step-down switching regulators. These ICs possess excellent line and load regulation abilities, effectively powering loads up to 3.0 A. Available in fixed output voltages of 3.3 V, 5.0 V, 12 V, and 15 V, along with an adjustable version, the LM2576T reduces the dependence on external components in power supply applications.

A defining characteristic of the LM2576T series is its efficient switch-mode power supply functionality, which substantially curtails heat dissipation. This feature frequently obviates the need for heatsinks, easing the thermal design process and cutting overall system costs. Efficient thermal management not only extends device lifespan but also ensures system reliability, which is mostly insistent in compact or densely populated circuit boards.

Featuring guaranteed ±4% output voltage tolerance and ±10% oscillator frequency tolerance, the LM2576T promises reliable performance. These specifications hold specific significance in applications that prioritize precision and stability. The LM2576T series incorporates several built-in protection features external shutdown, cycle-by-cycle current limiting, and thermal shutdown. These protections are useful for safeguarding both the regulator and the connected components, mirroring industry practices where redundant protection mechanisms are routinely employed. Such layers of defense enhance the robustness and dependability of electronic designs, preventing catastrophic failures.

LM2576T Pin Configuration

Pin Number	Pin Name	Description
1	Vin	This pin is the positive input supply for the LM2576 step-down switching regulator. A suitable input bypass capacitor must be present to minimize voltage transients and supply the switching currents needed by the regulator.
2	Output	This is the emitter of the internal switch. The saturation voltage (Vsat) of this output switch is typically 1.5 V. The PCB area connected to this pin should be minimized to reduce coupling to sensitive circuitry.
3	GND	Circuit ground pin. Refer to the printed circuit board layout guidelines for proper grounding practices.
4	Feedback	This pin senses the regulated output voltage to complete the feedback loop. The signal is divided by the internal resistor divider network (R2, R1) and applied to the error amplifier. In the adjustable version, this pin allows output voltage programming via an external resistor network.
5	ON/OFF	This pin allows the switching regulator circuit to be shut down using logic level signals, reducing the total input supply current to approximately 80 µA. A voltage above 1.4 V (up to +Vin) shuts the regulator off, while a lower voltage keeps it on.

LM2576T CAD Design

PCB Footprint

3D Visualization

In-depth Analysis of LM2576T Core Attributes

Feature	Details
Available Versions	3.3 V, 5.0 V, 12 V, 15 V, and Variable Output
Output Voltage Range	1.23 to 37 V ±4% (Maximum Over Line and Load Conditions)
Guaranteed Output Current	3.0 A
Input Voltage Range	Wide input voltage range
External Components Required	Only 4 external components
Oscillator Frequency	52 kHz Fixed Frequency Internal Oscillator
Shutdown Capability	TTL shutdown capability, low power standby mode
Efficiency	High efficiency
Inductors	Uses commonly available standard inductors
Protection Features	Thermal shutdown and current limit protection
Moisture Sensitivity Level (MSL)	MSL = 1
Package Availability	Pb−Free packages available

Technical Specifications

Type	Parameter
Lifecycle Status	ACTIVE (Last Updated: 1 week ago)
Factory Lead Time	4 Weeks
Mount	Through Hole
Mounting Type	Through Hole
Package / Case	TO-220-5 Formed Leads
Number of Pins	5
Operating Temperature	-40°C~125°C TJ
Packaging	Tube
Published	2000
JESD-609 Code	e3
Pbfree Code	Yes
Part Status	Active
Moisture Sensitivity Level (MSL)	1 (Unlimited)
Number of Terminations	5
ECCN Code	EAR99
Terminal Finish	Tin (Sn)
Terminal Position	ZIG-ZAG
Peak Reflow Temperature (Cel)	260°C
Time@Peak Reflow Temperature-Max (s)	40 seconds
Base Part Number	LM2576
Function	Step-Down
Number of Outputs	1
Efficiency	77%
Output Voltage	5V
Output Type	Fixed
Max Output Current	3A
Operating Supply Voltage	40V
Voltage - Input (Min)	7V
Input Voltage - Nom	12V
Analog IC - Other Type	SWITCHING REGULATOR
Output Configuration	Positive or Negative
Max Output Voltage	5V
Topology	Buck
Control Mode	VOLTAGE-MODE
Frequency - Switching	52kHz
Halogen Free	Halogen Free
Control Technique	PULSE WIDTH MODULATION
Synchronous Rectifier	No
Min Output Voltage	5V
Nominal Output Voltage	5V
Height	9.271mm
Length	10.54mm
Width	4.572mm
REACH SVHC	No SVHC
RoHS Status	ROHS3 Compliant
Lead Free	Lead Free

Comparable Components

Part Number

Manufacturer

Package / Case

Number of Pins

Number of Outputs

Max Output Current

Frequency - Switching

Input Voltage (Nom)

Voltage - Input (Min)

Min Output Voltage

Nominal Output Voltage

Output Voltage

Max Output Voltage

Efficiency

LM2576TV-5G

ON Semiconductor

TO-220-5 Formed Leads

5

1

3A

52kHz

12 V

7 V

5 V

5 V

5 V

5 V

77%

LM2576T-ADJ

ON Semiconductor

TO-220-5

5

1

3A

52kHz

12 V

7 V

1.23 V

-

-

37 V

77%

LM2576T-5.0/NOPB

Texas Instruments

TO-220-5

5

1

3A

-

12 V

7 V

5 V

5 V

5 V

5.25 V

77%

LM2576T-ADJG

ON Semiconductor

TO-220-5

5

1

3A

-

12 V

-

4.8 V

5 V

5 V

5.2 V

77%

LM2576T-005G

ON Semiconductor

TO-220-5

5

1

3A

-

12 V

7 V

-

-

-

37 V

77%

LM2576T Schematic Diagram

LM2576T Typical Use

LM2576T Testing Circuit

Fixed Voltage Output

100 μF, 75 V, Aluminum Electrolytic

1000 μF, 25 V, Aluminum Electrolytic

Schottky, MBR360

100 μH, Pulse Eng. P92108

2.0 kΩ, 0.1%

6.12 kΩ, 0.1%

To achieve a fixed voltage output, specific components are used.

• Aluminum Electrolytic Capacitors: These capacitors provide the required filtering to smooth voltage fluctuations. The 100 μF and 1000 μF capacitors are chosen for their capacity to handle different voltage levels, stabilizing the circuit under varying loads.

• Schottky Diode (MBR360): Known for its low forward voltage drop, this diode helps in minimizing power losses, aiding in the efficient operation of the power supply.

• High Precision Resistors (0.1% tolerance): With resistors of 2.0 kΩ and 6.12 kΩ, the precision is active for maintaining a consistent voltage output. This precise tolerance reflects the accumulated wisdom that accuracy can mitigate drift and enhance operational reliability.

Variable Voltage Output

Vout = Vref (1.0 + R2/R1)

R2 = R1 (Vout/Vref - 1.0)

Vref = 1.23 V, R1 = 1.0 kΩ - 5.0 kΩ

For producing a variable voltage output, we rely on the equation.

• Vout = Vref (1.0 + R2/R1): Here, with Vref set at 1.23 V, the output voltage can be finely tuned by choosing appropriate values for resistors R1 and R2 within the 1.0 kΩ to 5.0 kΩ range.

• R2 = R1 (Vout/Vref - 1.0): This formula allows for precise adjustment, and flexibility similar to applications where adapting voltage regulation is essential.

PCB Layout Considerations

In switching regulators, effective PCB layout is dominant due to the transient nature of switching currents, which can generate electromagnetic interference (EMI) and disrupt functionality.

• Minimizing Inductance and Ground Loops: Keep leads short and employ single-point grounding or a ground plane. This practice stabilizes the circuit and minimizes potential noise issues.

• Pin 2 and Feedback Wiring: The area related to Pin 2 (emitter of the internal switch) should be minimized, and feedback wiring must be kept as short as possible to reduce noise interference.

• Placement of Programming Resistors: Specifically, in adjustable versions, programming resistors should be placed close to the regulator to ensure accurate voltage adjustments, preventing voltage drops or noise from skewing the output.

High-Frequency Noise and EMI

The impact of high-frequency noise cannot be overstated in practical designs. Ensuring compact, low-inductance PCB layouts is a standard practice to bolster efficiency and reliability. Utilizing single-point grounding or a ground plane helps establish a stable reference point, thereby reducing noise.

Feedback Loop

Maintaining the feedback loop’s integrity is used for reliable performance. By positioning programming resistors near the regulator, signal accuracy is preserved, ensuring that any potential noise or voltage drop doesn't distort the desired output. This conscious placement underscores the careful attention to detail that distinguishes effective circuit design.

Alternatives to LM2576T

Part Number	Description	Manufacturer
LM2576HVT-ADJ	IC 7.5 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, PSFM5, TO-220, 5 PIN, Switching Regulator	National Semiconductor Corporation
LM2576TV-ADJG	7.5A SWITCHING REGULATOR, 63kHz SWITCHING FREQ-MAX, PZFM5, LEAD FREE, TO-220, 5 PIN	Rochester Electronics LLC
LM2576HVT-ADJ/NOPB	SIMPLE SWITCHER® 4V to 60V, 3A Low Component Count Step-Down Regulator 5-TO-220 -40 to 125	Texas Instruments
LM2576BT	Switching Regulator Voltage-mode 7.5A 63kHz Switching Freq-Max BIPolar PSFM5	Micrel Inc

LM2576T Common Applications

The LM2576T serves as a highly adaptable and dependable DC-DC converter, continually finding its role in various applications. It provides an elegant solution for stepping down voltage efficiently, making it a favored choice for a wide array of electronic devices and systems.

Power Supply for Microcontrollers

The LM2576T is often utilized for powering microcontrollers, mostly within embedded systems. Its capability to sustain a stable output voltage is useful for the reliable functioning of these delicate components. A stable power supply markedly enhances the reliability and performance of microcontroller-based systems. These systems find applications in industrial automation, consumer electronics, and automotive technology.

Battery-Powered Devices

In battery-operated devices, such as portable media players, handheld gaming consoles, and medical instruments, sustaining battery life is a dominant concern. The LM2576T’s efficiency minimizes power loss, thereby extending battery life. For remote medical devices, effective power management is active for prolonged operational periods without the necessity for frequent recharges.

Telecom Equipment

Telecommunications infrastructure demands robust and efficient voltage regulation. The LM2576T is frequently incorporated into power supplies for telecom equipment to ensure consistent performance. Reliable voltage regulation prevents communication breakdowns and enhances the overall stability of telecom networks. This stable operation is serious in cell towers and base stations, where uninterrupted service is domineering.

LED Lighting Systems

LED lighting systems reap substantial benefits from the LM2576T’s capacity to provide steady and efficient power. Whether used in residential, commercial, or automotive lighting, the converter guarantees a constant current to LEDs, bolstering their longevity and performance. In intelligent lighting systems, precise voltage control allows for adaptive lighting solutions that adjust brightness based on ambient conditions, thereby enhancing energy efficiency.

Industrial Automation

In industrial automation, the LM2576T powers various sensors, actuators, and control units. Its efficiency and reliability contribute to reduced downtime and heightened energy efficiency in automated systems. Implementing dependable voltage regulators in industrial settings can markedly cut maintenance costs and boost system uptime, thereby improving operational efficiency.

Consumer Electronics

The omnipresence of the LM2576T in consumer electronics, including laptops, tablets, and smartphones, highlights its extensive usefulness. Efficient power regulation is used for these devices as it directly affects their performance and your experience. A consistent voltage supply can enhance battery life and device performance, making consumer electronics more reliable.

Renewable Energy Systems

The LM2576T's integration into renewable energy solutions, such as solar power converters and wind energy systems, is instrumental in energy harnessing and regulation. Efficient voltage regulation plays a key role in optimizing the performance of these systems. In solar power applications, the LM2576T aids in maximizing energy harvested from solar panels by ensuring optimal voltage levels are maintained.

LM2576T Packaging Information

DIM	INCHES		MILLIMETERS
	(MIN)	(MAX)		(MIN)	(MAX)
A	0.572	0.613		14.529	15.57
B	0.390	0.415		9.906	10.541
C	0.170	0.180		4.318	4.572
D	0.025	0.038		0.635	0.965
E	0.048	0.055		1.219	1.397
F	0.850	0.935		21.590	23.749
G	0.067 BSC			1.702 BSC
H	0.166 BSC			4.216 BSC
J	0.015	0.025		0.381	0.635
K	0.900	1.100		22.860	27.940
L	0.320	0.365		8.128	9.271
N	0.320 BSC			8.128 BSC
Q	0.140	0.153		3.566	3.886
S	---	0.620		---	15.748
U	0.468	0.505		11.888	12.827
V	---	0.735		---	18.669
W	0.090	0.110		2.286	2.794

Notes:

• Dimensioning and tolerancing per ANSI Y14.5M, 1982.

• Controlling dimension: INCH.

• Dimension D does not include interconnect bar (dambar) protrusion. Dimension D, including protrusion, shall not exceed 0.043 (1.092) maximum.

Company Background

Since its birth in 1999, ON Semiconductor (NASDAQ: ON) has emerged as a trailblazer in the delivery of sophisticated technological solutions. The company directs its focus towards intelligent power and sensor integration. Over the years, it has etched its name in dynamic sectors such as automotive, industrial, and telecommunications. Notable advancements have been made in vehicle electrification, sustainable energy, and the evolving 5G infrastructure. Their dedication to innovation resonates through a vast product line designed to embrace a multitude of applications.

In the automotive sector, ON Semiconductor's cutting-edge technology fuels the shift towards electric and autonomous vehicles. Their high-performance power management solutions enhance the efficiency and range of modern electric vehicles. Innovations support the reduction of carbon footprints and improve vehicle safety and performance. Consider their major contributions to battery management systems and advanced driver-assistance systems (ADAS), which mirror the industry's relentless drive toward sustainable transportation.

Datasheet PDF

LM2576TV-5G Datasheets:

Cylindrical Battery Holders.pdf

LM2576.pdf

LM2576T-ADJ Datasheets:

Cylindrical Battery Holders.pdf

LM2576.pdf

LM2576T-ADJG Datasheets:

Cylindrical Battery Holders.pdf

LM2576.pdf

LM2576T-005G Datasheets:

Cylindrical Battery Holders.pdf

LM2576.pdf

Frequently Asked Questions [FAQ]

1. The output of my LM2576T-5.0 voltage regulator drops to 4.70 V under load. Why?

When experiencing a drop to 4.70 V, the high DC resistance of the inductor is often the underlying cause. Using a power inductor with lower resistance can significantly improve the situation. For example, an inductor with around 0.1Ω may effectively reduce the voltage drop. Careful selection of inductors based on their electrical characteristics ensures stable performance and efficiency in practical applications.

2. What is the difference between LM2576T-ADJ and LM2576T-5.0?

The LM2576T-ADJ allows for adjustable output voltage. Requires external resistors to set the desired voltage. Offers greater flexibility in various applications. The LM2576T-5.0 comes with an integrated reference resistor. Provides a fixed 5V output. Simplifies the design process. Ideal for applications needing a consistent output voltage.

3. Can LM2576 be used for boosting?

No, the LM2576 is strictly a step-down (buck) regulator. For situations requiring a voltage boost (step-up), you should consider alternatives. Suitable options include those designed specifically for boosting applications and ensuring efficient and reliable performance for step-up needs. When designing power supply systems, selecting the appropriate regulator—step-down or step-up—maximizes efficiency and satisfies the power requirements of the system.