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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

Texas Instruments LM2576S-3.3

Name: LM2576S-3.3
Brand: Texas Instruments
SKU: LM2576S-3.3
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LM2576S-3.3

Manufacturer:: Texas Instruments

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: TO-263-6, D2PAK (5 Leads + Tab), TO-263BA

Datasheet:: LM2576S-3.3.pdf

Description:: IC REG BUCK 3.3V 3A TO263

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Product details

Overview

LM2576S-3.3 from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC regulator in TO-220-5 (KC) package, delivering fixed 3.3-V output with ±4% tolerance over line and load, 52-kHz fixed-frequency operation, and TTL-compatible ON/OFF control. It replaces linear regulators in industrial power supplies, motor drives, and test equipment where thermal efficiency and minimal external components are critical.

For engineers reviewing the LM2576S-3.3 datasheet, LM2576S-3.3 pinout, LM2576S-3.3 application, or LM2576S-3.3 equivalent, key selection criteria include input voltage range (up to 40 V), 3-A continuous output current capability, integrated cycle-by-cycle current limiting, thermal shutdown protection, and compatibility with standard off-the-shelf inductors.

Technical Context

The LM2576S-3.3 implements a fixed-frequency buck topology with an internal 52-kHz oscillator, NPN power switch, and bandgap reference-based error amplifier. Its feedback loop uses a direct connection from OUTPUT to FEEDBACK for fixed-output versions, eliminating external resistor dividers.

Functional modes include active regulation (ON/OFF pin <1.2 V), shutdown (ON/OFF pin >1.4 V, 50-μA standby current), and overload protection via cycle-by-cycle peak current limiting (ICL = 4.2–6.9 A) and thermal shutdown. The device operates across −40°C to +125°C junction temperature with no minimum load requirement.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3 V ±4% over full line/load/temperature range - ensures stable logic supply without trimming.
Max Output Current	3 A continuous - supports mid-power embedded systems without external current boosting.
Input Voltage Range	4 V to 40 V - accommodates 5-V, 12-V, and 24-V rails while rejecting transients up to 45 V absolute max.
Oscillator Frequency	52 kHz (±10%) - enables use of low-cost, high-saturation-current inductors and reduces EMI filtering complexity.
Efficiency	75% at 12-V_IN/3.3-V_OUT/3-A - cuts heat sink size vs. linear regulators; no heatsink required at moderate ambient temperatures.
Standby Current	50 μA typical - enables low-power system sleep modes without auxiliary LDOs.
Saturation Voltage	1.4–2.0 V at 3-A - defines dropout behavior and impacts minimum input voltage for regulation.
Thermal Resistance	R_θJA = 32.4°C/W (TO-220) - sets maximum power dissipation limit (≈3.1 W) under natural convection on standard PCB.

Pinout & Package

LM2576S-3.3 is supplied in KC (TO-220-5) package with exposed tab thermally connected to GROUND. Mounting requires mechanical fastening and thermal interface to heatsink for >1.5-A continuous operation.

Pin/Terminal	Circuit Role	Design Meaning
1 - VIN	Power input	Connects to high-side NPN collector; must be decoupled with short-path 100-μF+ electrolytic capacitor to minimize switching noise injection.
2 - OUTPUT	Switching node	Drives external inductor and catch diode cathode; high dv/dt node requiring tight layout and ground plane clearance.
3 - GROUND	Power and signal reference	Common return for input cap, output cap, and feedback path; shortest possible trace to VIN and OUTPUT pins.
4 - FEEDBACK	Regulation sense	Internally tied to 3.3-V reference; for fixed version, connect directly to output capacitor - no external divider needed.
5 - ON/OFF	Enable control	TTL-compatible digital input: <1.2 V = ON, >1.4 V = OFF; 50-μA standby current when pulled high.
TAB	Thermal pad / GND	Electrically and thermally connected to GROUND; must be soldered to large copper pour or heatsink for thermal management.

Key Features

Feature	Design Value
Fixed 3.3-V output	Eliminates external feedback resistors - reduces BOM count, layout area, and calibration risk in 3.3-V logic supply designs.
Integrated current limiting	4.2–6.9-A cycle-by-cycle peak limit protects switch and inductor during startup, overload, or short-circuit events without external sensing.
Thermal shutdown	Automatically disables regulator above 150°C junction temperature - prevents permanent damage during sustained overload or poor heatsinking.
52-kHz fixed frequency	Enables predictable EMI filtering and simplifies inductor selection using standardized 100–220-μH parts rated for ≥3-A DC and 5-A peak.
TTL shutdown	50-μA standby current and logic-level compatible enable pin allow direct interfacing with microcontrollers or power sequencers.
Wide input range	4–40-V operation supports unregulated 12-V and 24-V industrial rails, battery inputs down to 4 V, and transient-tolerant designs.

Applications

Industrial Power Supply	Motor Drive Control
Use Scenario: Providing regulated 3.3-V bias for microcontrollers, gate drivers, and sensors in programmable logic controllers (PLCs) operating from 24-V DC bus. IC Role / Device Role / Timing Role: Primary step-down regulator converting noisy 24-V rail to clean 3.3-V logic supply with ripple <50 mV_pp. Use Value: Eliminates need for separate linear regulator stage, reducing board space by 40% and thermal load by >70% vs. 78L05-based solutions.	Use Scenario: Generating 3.3-V supply for position encoder interfaces and current-sense amplifiers in brushed DC motor controllers. IC Role / Device Role / Timing Role: Non-isolated, high-efficiency local regulator powering analog front-end circuitry adjacent to motor H-bridge. Use Value: Maintains regulation during motor stall events (input dips to 8 V) due to wide 4–40-V input range and robust current limiting.
Test Equipment	Appliance Control Board
Use Scenario: Powering FPGA configuration memory and ADC reference circuits in portable multimeters and signal generators. IC Role / Device Role / Timing Role: Low-noise, fixed-output DC-DC converter supplying precision analog and digital subsystems. Use Value: Achieves <0.5% output drift over temperature and <10-mV load transient deviation - meets Class II metrology requirements.	Use Scenario: Delivering 3.3-V power to MCU, display driver, and communication ICs in smart washing machine main control boards. IC Role / Device Role / Timing Role: Main system regulator operating from 12-V battery or AC/DC adapter with automotive-grade thermal robustness. Use Value: Withstands 40-V load dump transients and operates reliably at 85°C ambient - eliminates field failures linked to thermal derating.

Industrial Power Supply

Motor Drive Control

Use Scenario: Providing regulated 3.3-V bias for microcontrollers, gate drivers, and sensors in programmable logic controllers (PLCs) operating from 24-V DC bus.

IC Role / Device Role / Timing Role: Primary step-down regulator converting noisy 24-V rail to clean 3.3-V logic supply with ripple <50 mV_pp.

Use Value: Eliminates need for separate linear regulator stage, reducing board space by 40% and thermal load by >70% vs. 78L05-based solutions.

Use Scenario: Generating 3.3-V supply for position encoder interfaces and current-sense amplifiers in brushed DC motor controllers.

IC Role / Device Role / Timing Role: Non-isolated, high-efficiency local regulator powering analog front-end circuitry adjacent to motor H-bridge.

Use Value: Maintains regulation during motor stall events (input dips to 8 V) due to wide 4–40-V input range and robust current limiting.

Test Equipment

Appliance Control Board

Use Scenario: Powering FPGA configuration memory and ADC reference circuits in portable multimeters and signal generators.

IC Role / Device Role / Timing Role: Low-noise, fixed-output DC-DC converter supplying precision analog and digital subsystems.

Use Value: Achieves <0.5% output drift over temperature and <10-mV load transient deviation - meets Class II metrology requirements.

Use Scenario: Delivering 3.3-V power to MCU, display driver, and communication ICs in smart washing machine main control boards.

IC Role / Device Role / Timing Role: Main system regulator operating from 12-V battery or AC/DC adapter with automotive-grade thermal robustness.

Use Value: Withstands 40-V load dump transients and operates reliably at 85°C ambient - eliminates field failures linked to thermal derating.

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2576T-3.3	Same electrical specs; TO-220-5 package with different lead form (straight vs. bent leads) and minor thermal resistance variation (R_θJA = 32.4°C/W vs. 33.1°C/W).	No functional difference; identical pinout and performance - suitable for automated through-hole assembly where lead geometry matches pick-and-place tooling.	Select LM2576T-3.3 only when board layout or assembly process requires straight-lead TO-220 variant.
LM2576HVS-3.3	Higher 60-V max input (vs. 40 V); otherwise identical 3.3-V output, 3-A rating, and pinout - shares same KC package and thermal characteristics.	Required for 48-V telecom or industrial systems where input transients exceed 40 V; adds margin against surge events without redesigning layout or magnetics.	Choose LM2576HVS-3.3 when input rail exceeds 40 V or safety margin against 45-V absolute max rating is insufficient.

Compared with LM2576S-3.3, LM2576T-3.3 offers identical regulation but differs only in lead configuration for assembly compatibility, while LM2576HVS-3.3 extends input voltage headroom to 60 V - enabling use in higher-voltage systems without changing PCB footprint or component selection.

Availability

LM2576S-3.3 is available at Aetrix Electronics and suitable for industrial power supplies, motor drive control units, test and measurement equipment requiring stable component supply and long-term manufacturing continuity.

Supply support for LM2576S-3.3 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, designing and manufacturing analog, embedded processing, and logic devices for industrial, automotive, and consumer markets.

The LM2576 series belongs to TI's SIMPLE SWITCHER® power converter family, engineered for ease-of-use in cost-sensitive, medium-power DC-DC applications where reliability, thermal efficiency, and minimal external component count are prioritized over ultra-high efficiency or advanced features like synchronization.

FAQ

What is the maximum input voltage rating for LM2576S-3.3?

The LM2576S-3.3 has a recommended maximum input voltage of 40 V and an absolute maximum rating of 45 V. Exceeding 40 V continuously may trigger thermal shutdown or reduce lifetime reliability. For systems with 48-V nominal rails or high-voltage transients, the LM2576HVS-3.3 (60-V rated) is the appropriate alternative. Always observe derating curves in the datasheet for safe operation across temperature.

Does LM2576S-3.3 require an external feedback resistor network?

No, the LM2576S-3.3 does not require external feedback resistors. As a fixed-output variant, its internal reference and error amplifier are configured for 3.3 V; the FEEDBACK pin must be connected directly to the output capacitor's positive terminal. Adding external resistors will disrupt regulation and cause output voltage error. Only adjustable versions (e.g., LM2576ADJ) use external resistor dividers.

How much output current can LM2576S-3.3 deliver continuously?

The LM2576S-3.3 is specified for 3-A continuous DC output current under recommended operating conditions (T_J ≤ 125°C, proper heatsinking, and adequate input/output capacitance). Actual achievable current depends on ambient temperature, PCB copper area, and heatsink effectiveness - at 25°C ambient with TO-220 mounted to 1-in² copper, ~2.2 A is sustainable without thermal throttling. Derate linearly above 25°C per the thermal resistance spec (32.4°C/W).

What is the purpose of the ON/OFF pin on LM2576S-3.3?

The ON/OFF pin on LM2576S-3.3 provides TTL-compatible enable/disable control: pulling it below 1.2 V activates regulation, while pulling it above 1.4 V places the device in low-power shutdown mode with 50-μA typical quiescent current. This pin must never be left floating - tie to GND for always-on operation or drive with a microcontroller GPIO. It is not intended for PWM dimming or frequency modulation.

Can LM2576S-3.3 be used without a heatsink?

LM2576S-3.3 can operate without an external heatsink at light loads (<1 A) and ambient temperatures <40°C when mounted on ≥2 oz copper with ≥1 in² thermal pad. At full 3-A load, junction temperature rises rapidly - for reliable continuous operation, a heatsink (or ≥4 in² copper pour) is mandatory. Thermal simulation using R_θJA = 32.4°C/W and P_D ≈ (V_IN−3.3)×I_OUT×(1−η) confirms necessity above 1.5 A in typical enclosures.

LM2576S-3.3 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: SIMPLE SWITCHER®

Package/Case:: TO-263-6, D2PAK (5 Leads + Tab), TO-263BA

Packaging:: Tube

Product Status:: Obsolete

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Fixed

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 40V

Voltage - Output (Min/Fixed):: 3.3V

Voltage - Output (Max):: -

Current - Output:: 3A

Frequency - Switching:: 52kHz

Synchronous Rectifier:: No

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: TO-263 (DDPAK-5)

LM2576S-3.3 FAQ

1.How can I place an order for LM2576S-3.3 through Aetrix?

Please submit a Request for Quotation (RFQ) for LM2576S-3.3 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LM2576S-3.3 reliable?

The price and inventory of LM2576S-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2576S-3.3 is usually 5 days.

3.What payment methods are accepted for LM2576S-3.3?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2576S-3.3 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM2576S-3.3?

LM2576S-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM2576S-3.3 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LM2576S-3.3?

For technical support, including LM2576S-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2576S-3.3 requirements.

6.How does Aetrix verify that LM2576S-3.3 is sourced from the original manufacturer or authorized distributors?

All LM2576S-3.3 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM2576S-3.3 meets industry standards.

7.What is the process for return or replacement of LM2576S-3.3?

All LM2576S-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2576S-3.3, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LM2576S-3.3 part is unused and in its original packaging.

Return procedure for LM2576S-3.3:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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