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Texas Instruments LM2576SX-3.3
- Part No.:
- LM2576SX-3.3
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2576SX-3.3.pdf
- Description:
- IC REG BUCK 3.3V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,720
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Product details
Overview
LM2576SX-3.3 from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC converter in TO-220-5 (KC) package, delivering fixed 3.3-V output with ±4% regulation 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 LM2576SX-3.3 datasheet, LM2576SX-3.3 pinout, LM2576SX-3.3 application, or LM2576SX-3.3 equivalent, this page provides verified pin functions, thermal performance data, shutdown current (50 μA), output voltage tolerance (±4%), and real-world design meaning for layout, heatsinking, and system-level fault protection.
Technical Context
The LM2576SX-3.3 integrates a 3-A NPN switch, fixed 52-kHz oscillator, error amplifier, current-limit comparator, and thermal shutdown circuit. Its non-synchronous buck architecture uses an external catch diode and requires only four external components: input capacitor, output capacitor, inductor, and feedback network (shorted for fixed 3.3-V version).
It operates across 40 V max input (LM2576 variant), delivers regulated 3.3 V at up to 3 A, and supports active shutdown via the ON/OFF pin (logic-high = off, 50 μA standby). Cycle-by-cycle current limiting (ICL = 4.2–6.9 A) and thermal shutdown provide full fault protection without external circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over full operating temperature (−40°C to +125°C) and load (0.5–3 A); ensures stable logic supply for microcontrollers and FPGAs without trimming. |
| Max Input Voltage | 40 V - defines maximum unregulated rail compatibility (e.g., 24-V industrial bus with transient margin); HV variant LM2576HV-3.3 supports 60 V. |
| Switching Frequency | 52 kHz (±10%) - enables use of low-cost, high-saturation-current inductors; avoids audible noise and simplifies EMI filtering vs. MHz-range converters. |
| Output Current | 3 A continuous - supports mid-power applications like motor drivers or multi-rail PSUs without parallel devices or forced air cooling. |
| Standby Current | 50 μA typical at ON/OFF = high - enables low-power sleep modes in battery-backed systems or remote sensors without auxiliary LDOs. |
| Thermal Resistance | RθJA = 32.4°C/W (TO-220 KC package, JEDEC 4-layer board) - determines minimum heatsink area required for 3-A operation at ambient ≤70°C. |
| Saturation Voltage | VSAT = 1.4–2.0 V at 3 A - directly impacts conduction loss and efficiency; mandates careful selection of external catch diode forward voltage. |
Pinout & Package
LM2576SX-3.3 is supplied in KC (TO-220-5) package with integrated heatsink tab connected to GND. The 5-pin top-view layout prioritizes thermal and EMI performance: VIN and GND pins are adjacent for low-inductance input loop; OUTPUT pin is isolated for clean switching node routing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: VIN | Input supply connection | Connects to collector of internal NPN switch; must be decoupled with ≥100-μF electrolytic capacitor placed within 5 mm to minimize high-frequency ringing and EMI. |
| 2: OUTPUT | Switching node | Emitter of internal NPN switch; connects directly to inductor and cathode of external Schottky diode; requires shortest possible trace to reduce voltage spikes and radiated emissions. |
| 3: GROUND | Power and signal reference | Common return for input/output capacitors and feedback network; must share low-impedance copper pour with VIN and OUTPUT ground paths to avoid noise coupling. |
| 4: FEEDBACK | Regulation sense input | Internally tied to 3.3-V output for fixed versions; left unconnected in LM2576SX-3.3 - no external resistor divider needed, eliminating calibration drift and component count. |
| 5: ON/OFF | Enable/disable control | TTL-compatible digital input; <1.2 V = active regulation, >1.4 V = shutdown (50 μA IQ); must be hard-connected to GND or driven by logic - never left floating. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed-output simplicity | Zero external feedback components required for 3.3-V operation - eliminates resistor tolerance errors, temperature drift, and PCB space for divider network. |
| Integrated protection | Cycle-by-cycle current limiting (4.2–6.9 A) and thermal shutdown prevent damage during overload or poor heatsinking - no external sensing or latch circuitry needed. |
| Low-component count | Only four external parts (CIN, COUT, L, D) required - reduces BOM cost, assembly steps, and failure points versus controller-based buck designs. |
| High-efficiency replacement | Up to 88% efficiency (at 12-V input, 3-A load) vs. <40% for linear regulators - eliminates large heatsinks and enables compact, convection-cooled enclosures. |
| Robust shutdown interface | 50-μA standby current and wide logic threshold (VIL ≤ 1.2 V, VIH ≥ 2.2 V) allow direct interfacing with microcontrollers, optocouplers, or simple pull-down resistors without level-shifting. |
Applications
| Industrial Motor Drives | Merchant Network PSU |
|---|---|
Use Scenario: Powering gate drivers, logic controllers, and sensor interfaces in 24-V DC-fed brushless motor modules. IC Role / Device Role / Timing Role: Primary 3.3-V buck regulator supplying FPGA configuration, MCU core, and isolated communication ICs. Use Value: Delivers 3 A continuously with ±4% output stability across −40°C to +85°C ambient, enabling reliable startup and operation without derating. |
Use Scenario: Generating auxiliary 3.3-V rail in AC/DC front-end power supplies for enterprise switches and routers. IC Role / Device Role / Timing Role: Secondary-side non-isolated regulator converting 12-V intermediate bus to clean 3.3-V for PHYs and management processors. Use Value: 52-kHz fixed frequency allows predictable EMI filter design; TO-220 package enables direct bolt-on heatsinking to chassis for thermal continuity. |
| Appliance Control Boards | Test & Measurement Equipment |
Use Scenario: Providing regulated 3.3-V supply to microcontroller, display driver, and relay interface circuits in smart home appliances. IC Role / Device Role / Timing Role: Main system regulator replacing linear solutions to eliminate heatsink requirements and reduce board area. Use Value: 32.4°C/W RθJA (TO-220) allows full 3-A output with only 25 cm² copper pour - fits constrained appliance PCB layouts. |
Use Scenario: Supplying precision analog front-ends, ADC references, and digital logic in portable multimeters and signal generators. IC Role / Device Role / Timing Role: Low-noise 3.3-V source with external LC filter (per Figure 7-4) to suppress switching ripple below 10 mVpp. Use Value: Fixed 3.3-V output eliminates feedback resistor drift; ±4% tolerance meets 3.3-V ±5% spec for most embedded peripherals. |
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 and pinout; differs only in package marking (T = TO-220, SX = TO-220 with tape-and-reel packaging code) | No functional difference - identical thermal, electrical, and mechanical behavior in circuit | Select LM2576T-3.3 for tube packaging; LM2576SX-3.3 for automated SMT placement with tape-and-reel delivery. |
| LM2576HV-3.3 | Supports 60-V max input (vs. 40 V); otherwise identical 3.3-V output, 3-A rating, and pinout | Required for 48-V telecom or automotive battery-supplied systems where input transients exceed 40 V | Choose LM2576HV-3.3 only when input voltage exceeds 40 V; not drop-in for standard 24-V/36-V rails due to higher cost and same thermal profile. |
Compared with LM2576SX-3.3, LM2576T-3.3 offers identical performance in tube format for prototyping, while LM2576HV-3.3 extends input range to 60 V at no change to output accuracy or thermal design - making it suitable only for high-input-voltage systems, not general replacement.
Availability
LM2576SX-3.3 is available at Aetrix Electronics and suitable for industrial motor drives, merchant network PSUs, and appliance control boards requiring stable component supply, long-term lifecycle support, and traceable sourcing from authorized channels.
Supply support for LM2576SX-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 leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability power conversion ICs.
The LM2576 series was designed as a robust, easy-to-use SIMPLE SWITCHER® solution for cost-sensitive industrial and consumer applications needing 3-A buck regulation without complex controller design or external MOSFETs.
FAQ
What is the maximum input voltage rating for LM2576SX-3.3?
The LM2576SX-3.3 has a maximum input voltage rating of 40 V, as specified in the Absolute Maximum Ratings table. Exceeding this voltage risks permanent damage. For applications requiring up to 60 V input, the LM2576HV-3.3 variant must be used instead - it shares the same 3.3-V output and pinout but is rated for higher input stress.
Does LM2576SX-3.3 require external feedback resistors?
No, LM2576SX-3.3 does not require external feedback resistors. As a fixed-output version, its internal feedback divider is factory-trimmed to 3.3 V, and the FEEDBACK pin is internally connected to the output. External resistors are only needed for the adjustable (ADJ) variant - using them with LM2576SX-3.3 would disrupt regulation and is not supported.
What is the typical standby current of LM2576SX-3.3 in shutdown mode?
The typical standby current of LM2576SX-3.3 in shutdown mode is 50 μA, measured when the ON/OFF pin voltage exceeds 1.4 V. This ultra-low quiescent current enables energy-efficient system-level power gating, especially in battery-backed or always-on monitoring applications where standby power budget is critical.
Can LM2576SX-3.3 be used without a heatsink?
LM2576SX-3.3 can operate without an external heatsink only at light loads (<500 mA) and low ambient temperatures (<40°C), given its RθJA of 32.4°C/W. At full 3-A load and 70°C ambient, junction temperature exceeds 125°C without heatsinking. A minimum 25 cm² copper pour or small aluminum heatsink is required for continuous 3-A operation per TI's thermal guidelines.
What type of external diode is recommended for LM2576SX-3.3?
A Schottky diode with ≥3-A average current rating, ≥50-V PIV, and low forward voltage (e.g., 1N5822 or SB560) is recommended for LM2576SX-3.3. The diode must handle peak currents up to 6.9 A (current limit threshold) and be mounted close to the OUTPUT and GND pins to minimize parasitic inductance and voltage overshoot during switching transitions.
LM2576SX-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:
- Tape & Reel (TR)
- 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)
LM2576SX-3.3 FAQ
1.How can I place an order for LM2576SX-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2576SX-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 LM2576SX-3.3 reliable?
The price and inventory of LM2576SX-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 LM2576SX-3.3 is usually 5 days.
3.What payment methods are accepted for LM2576SX-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2576SX-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2576SX-3.3?
LM2576SX-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2576SX-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 LM2576SX-3.3?
For technical support, including LM2576SX-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2576SX-3.3 requirements.
6.How does Aetrix verify that LM2576SX-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2576SX-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 LM2576SX-3.3 meets industry standards.
7.What is the process for return or replacement of LM2576SX-3.3?
All LM2576SX-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2576SX-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 LM2576SX-3.3 part is unused and in its original packaging.
Return procedure for LM2576SX-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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