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Texas Instruments LM2576SX-3.3/NOPB
- Part No.:
- LM2576SX-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2576SX-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 3A TO263
- Quantity:
- Payment:
- Shipping:
Inventory:1,852
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Product details
Overview
LM2576SX-3.3/NOPB from Texas Instruments is a monolithic 3-A non-synchronous step-down DC-DC converter in TO-263 (DDPAK) package, delivering fixed 3.3-V output with ±4% regulation over line and load, 40-V max input, 52-kHz fixed-frequency operation, and integrated thermal shutdown and cycle-by-cycle current limiting - used in industrial power supplies and embedded system rails.
For engineers reviewing the LM2576SX-3.3/NOPB datasheet, LM2576SX-3.3/NOPB pinout, LM2576SX-3.3/NOPB application, or LM2576SX-3.3/NOPB equivalent, key selection considerations include input voltage range (up to 40 V), 3-A continuous output capability, ON/OFF logic control interface, thermal performance on PCB copper area, and compatibility with standard off-the-shelf inductors.
Technical Context
The LM2576SX-3.3/NOPB implements a fixed-frequency buck topology with internal 52-kHz oscillator, built-in 3-A NPN switch, and voltage-mode error amplifier referenced to 1.23-V internal bandgap. It operates in continuous conduction mode under full load and transitions to discontinuous mode at light loads without instability.
Its functional block includes undervoltage lockout (UVLO) inherent in startup behavior, TTL-compatible ON/OFF pin enabling low-power standby (50-μA typical), and cycle-by-cycle peak current limiting set at 4.2–6.9 A (typical 5.8 A), with automatic frequency foldback to ~11 kHz during overload or short-circuit conditions.
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), ensuring stable microcontroller core rail without external feedback network. |
| Max Input Voltage | 40 V - supports wide-input industrial and automotive battery-supplied systems without pre-regulation. |
| Output Current | 3 A DC continuous - drives multiple digital ICs, FPGAs, or motor drivers directly from single-stage conversion. |
| Oscillator Frequency | 52 kHz (47–58 kHz range) - enables use of low-cost, high-saturation-current toroidal or shielded inductors with minimal EMI filtering. |
| Efficiency | 75% at 12-V input / 3-A load - reduces thermal load vs. linear regulators; eliminates need for heatsink in many PCB layouts with ≥1 in² copper pour. |
| Standby Current | 50 μA typical at ON/OFF = HIGH - enables low-power system sleep modes without auxiliary LDOs. |
| Saturation Voltage | 1.8 V max at 3-A load - defines minimum dropout: requires VIN ≥ VOUT + VSAT ≈ 5.1 V for regulation. |
Pinout & Package
LM2576SX-3.3/NOPB uses the KTT (DDPAK/TO-263-5) surface-mount package with 10.16 mm × 8.42 mm body size and exposed thermal pad connected internally to GND. Thermal resistance is RθJA = 42.6°C/W on JEDEC 4-layer board, reduced to 32°C/W with ≥1.6 in² PCB copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Power input | Connects to collector of internal NPN switch; must be decoupled with low-ESR 100-μF+ capacitor placed within 5 mm for stability. |
| 2 - OUTPUT | Switching node | Emitter of internal transistor; connects directly to inductor and catch diode anode - critical high-dI/dt path requiring minimized loop area. |
| 3 - GROUND | Power return | Common reference for internal circuitry and thermal pad; requires low-inductance connection to input/output capacitors and PCB ground plane. |
| 4 - FEEDBACK | Voltage sense | Internally tied to 3.3-V output; no external divider needed - simplifies layout and eliminates resistor tolerance drift errors. |
| 5 - ON/OFF | Enable control | TTL-compatible logic input: <1.2 V = active, >1.4 V = shutdown; 12–30 μA input current allows direct MCU GPIO drive. |
| TAB | Thermal & GND | Exposed metal pad soldered to PCB copper pour for thermal relief; electrically connected to GND - mandatory for thermal performance and EMI reduction. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3-V output | Eliminates external resistor divider, reducing BOM count, layout sensitivity, and long-term drift - ideal for noise-sensitive digital rails. |
| Integrated current limiting | Peak cycle-by-cycle protection at 5.8-A typical prevents switch failure during inrush or short-circuit, enabling robust field-deployed designs. |
| Thermal shutdown | Automatic recovery after junction temperature exceeds 150°C - protects against sustained overload or poor heatsinking without latch-up. |
| Low-standby quiescent current | 50-μA typical in shutdown enables battery-backed systems to maintain weeks of standby time without recharge. |
| Standard inductor compatibility | Optimized for off-the-shelf 15–100-μH shielded power inductors - avoids custom magnetics and accelerates prototyping. |
Applications
| Industrial PLC Power Rail | Embedded Controller Core Supply |
|---|---|
Use Scenario: Providing regulated 3.3-V power to ARM Cortex-M7 microcontrollers and CAN transceivers in programmable logic controllers operating from 24-V DC bus. IC Role / Device Role / Timing Role: Primary buck regulator generating clean, low-noise core voltage with fast transient response to CPU load changes. Use Value: Delivers 3-A peak current during burst processing while maintaining ±4% regulation and 75% efficiency - reducing heat generation in sealed enclosures. | Use Scenario: Powering FPGA configuration memory and I/O banks in edge AI gateways with variable thermal loading across ambient temperatures. IC Role / Device Role / Timing Role: Fixed-output DC-DC converter supplying stable 3.3-V rail independent of input ripple from upstream AC/DC adapter. Use Value: Internal 1.23-V reference and voltage-mode control ensure consistent regulation across −40°C to +85°C - eliminating need for external trimming. |
| Motor Drive Logic Supply | Test Equipment Auxiliary Rail |
Use Scenario: Generating isolated 3.3-V logic supply for gate drivers and position encoder interfaces in 48-V BLDC motor inverters. IC Role / Device Role / Timing Role: Non-isolated buck stage converting main DC bus to low-voltage control domain with ON/OFF synchronized to motor enable signal. Use Value: TTL-compatible enable pin allows precise sequencing with motor controller startup - minimizing inrush into downstream logic. | Use Scenario: Delivering calibrated 3.3-V reference rail for ADC front-ends and digital signal processors in portable oscilloscopes and spectrum analyzers. IC Role / Device Role / Timing Role: High-stability voltage source with low output ripple (<50 mVpp typical) and excellent line regulation (0.2%/V). Use Value: Fixed internal feedback ensures ±4% accuracy without calibration - meeting Class II measurement instrument requirements. |
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 | TO-220-5 package (KC), higher RθJA = 32.4°C/W, same electrical specs and pinout. | Requires mechanical heatsink for >1.5-A loads; less suitable for space-constrained SMT assemblies. | Select when through-hole mounting, manual assembly, or legacy board compatibility is required. |
| LM2596SX-3.3 | Higher switching frequency (150 kHz), lower max input (40 V), same 3-A rating and TO-263 package. | Better transient response and smaller external inductors/capacitors; slightly lower efficiency at high VIN/VOUT ratios. | Select when faster load step response or reduced solution size is prioritized over absolute peak efficiency. |
Compared with LM2576SX-3.3/NOPB, LM2576T-3.3 offers identical regulation but demands more thermal management in SMT layouts, while LM2596SX-3.3 trades 52-kHz simplicity for 150-kHz compactness - making the original optimal for cost-sensitive, thermally constrained industrial rails where proven reliability outweighs size reduction.
Availability
LM2576SX-3.3/NOPB is available at Aetrix Electronics and suitable for industrial PLCs, embedded controller power rails, motor drive logic supplies, and test equipment auxiliary rails requiring stable component supply and long-term manufacturability.
Supply support for LM2576SX-3.3/NOPB 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 drop-in, high-efficiency replacement for linear regulators in medium-power industrial and embedded applications - emphasizing simplicity, fault resilience, and broad input voltage tolerance.
FAQ
What is the maximum input voltage rating for LM2576SX-3.3/NOPB?
The LM2576SX-3.3/NOPB has an absolute maximum input voltage of 45 V and a recommended maximum operating input voltage of 40 V. Exceeding 40 V risks exceeding safe operating area limits under load, especially at elevated temperatures. The HV variant (LM2576HV) supports up to 60 V, but LM2576SX-3.3/NOPB is strictly rated for 40 V max per TI's SNVS107G datasheet Section 6.3.
Does LM2576SX-3.3/NOPB require external feedback resistors?
No, LM2576SX-3.3/NOPB does not require external feedback resistors. As a fixed-output version, its FEEDBACK pin (Pin 4) is internally connected to the 3.3-V output node. External resistor dividers are only needed for the adjustable (ADJ) variant. This simplifies layout and improves long-term output accuracy by removing resistor tolerance and temperature drift variables.
What thermal performance can be expected from LM2576SX-3.3/NOPB on a standard PCB?
On a JEDEC 4-layer board, LM2576SX-3.3/NOPB exhibits RθJA = 42.6°C/W. With 1 in² of 2-oz copper connected to the exposed thermal tab, this improves to ~37°C/W; with ≥1.6 in², it reaches 32°C/W. At 3-A load and 12-V input, dissipation is ~2.7 W - resulting in ~85°C junction rise above ambient with 32°C/W cooling, well within the 125°C max operating limit.
Can LM2576SX-3.3/NOPB be synchronized to an external clock?
No, LM2576SX-3.3/NOPB cannot be synchronized to an external clock. It uses an internal fixed-frequency 52-kHz oscillator with ±10% tolerance (42–63 kHz). There is no SYNC pin or frequency-adjust capability. For synchronizable alternatives, consider newer TI parts like LM76003 or LMR51430, which support external clock injection and programmable switching frequencies.
What protection features are integrated into LM2576SX-3.3/NOPB?
LM2576SX-3.3/NOPB integrates cycle-by-cycle current limiting (trip point 4.2–6.9 A), thermal shutdown (150°C junction), and undervoltage lockout (inherent during startup). It also features automatic frequency foldback to ~11 kHz during overload or short-circuit, reducing average power dissipation. No external components are required to enable these protections - they are fully internal and always active.
LM2576SX-3.3/NOPB 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:
- Active
- 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/NOPB FAQ
1.How can I place an order for LM2576SX-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2576SX-3.3/NOPB 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/NOPB reliable?
The price and inventory of LM2576SX-3.3/NOPB 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/NOPB is usually 5 days.
3.What payment methods are accepted for LM2576SX-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2576SX-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2576SX-3.3/NOPB?
LM2576SX-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2576SX-3.3/NOPB 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/NOPB?
For technical support, including LM2576SX-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2576SX-3.3/NOPB requirements.
6.How does Aetrix verify that LM2576SX-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2576SX-3.3/NOPB 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/NOPB meets industry standards.
7.What is the process for return or replacement of LM2576SX-3.3/NOPB?
All LM2576SX-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2576SX-3.3/NOPB, 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/NOPB part is unused and in its original packaging.
Return procedure for LM2576SX-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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