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Microchip Technology LM2576-3.3WU
- Part No.:
- LM2576-3.3WU
- Manufacturer:
- Microchip Technology
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2576-3.3WU.pdf
- Description:
- IC REG BUCK 3.3V 3A TO263-5
- Quantity:
- Payment:
- Shipping:
Inventory:440
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Product details
Overview
LM2576-3.3WU from Micrel is a fixed-output 3.3V, 3A step-down (buck) switching regulator in TO-263-5 package, featuring 52kHz fixed-frequency operation, ±3% output voltage tolerance over line/load/temperature, and integrated thermal shutdown and cycle-by-cycle current limiting. It replaces linear regulators in industrial power supplies, embedded systems, and board-level DC-DC conversion where efficiency and minimal external components are critical.
For engineers reviewing the LM2576-3.3WU datasheet, LM2576-3.3WU pinout, LM2576-3.3WU application, or LM2576-3.3WU equivalent, key selection considerations include input voltage range (4V–40V), guaranteed 3A output current, standby current <200µA, and compatibility with standard off-the-shelf inductors - all validated for operation from –40°C to +85°C junction temperature.
Technical Context
The LM2576-3.3WU integrates a 52kHz oscillator, error amplifier with 1.23V internal reference, PWM comparator, 3A NPN switch, and protection circuitry including thermal shutdown and peak-current limiting. Its feedback loop is internally compensated, requiring only four external components for full operation: input capacitor, output capacitor, catch diode, and power inductor.
It operates in continuous conduction mode with up to 98% maximum duty cycle, enabling low dropout behavior at high input voltages. The ON/OFF control pin supports logic-level shutdown with <200µA standby current, while saturation voltage of the internal switch is specified at ≤2.0V (max) at 3A, directly impacting conduction losses and thermal design.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% over 0.5A–3A load and 6V–40V input - ensures stable rail for 3.3V microcontrollers and FPGAs without trimming. |
| Max Output Current | 3A DC - supports single-rail powering of mid-power digital loads without external current boosting. |
| Input Voltage Range | 4V to 40V - accommodates wide-input industrial, automotive, and telecom supply rails with no pre-regulation needed. |
| Switching Frequency | 52kHz ±10% - enables use of low-cost, high-saturation-current toroidal or drum-core inductors with minimal EMI filtering. |
| Efficiency | 75% at 12VIN/3.3VOUT/3A - reduces heat dissipation vs. linear regulators, often eliminating need for heatsink in TO-263 package. |
| Standby Current | <200µA when ON/OFF pin = 5V - enables low-power sleep modes in battery-backed or energy-sensitive systems. |
| Thermal Protection | Internal thermal shutdown with 100% burn-in - prevents catastrophic failure during overload or poor PCB thermal design. |
Pinout & Package
LM2576-3.3WU uses the 5-lead TO-263 (also known as D²PAK) surface-mount package with exposed thermal pad. Pin 3 (GND) and the underside thermal pad are electrically connected and must be soldered to a large copper pour for thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Unregulated input supply connection | Accepts 4V–40V DC; requires local 100µF electrolytic bypass near pin to suppress input ripple and switching transients. |
| 2 - OUTPUT | Switched output node | Drives external catch diode and inductor; high dv/dt node requiring short trace routing to minimize EMI and ringing. |
| 3 - GND | Power and signal ground reference | Common return for internal switch, error amp, and thermal pad; must be low-impedance connection to minimize noise coupling. |
| 4 - FEEDBACK | Voltage sense input (not used in fixed-output version) | Internally tied to 3.3V output; unused in LM2576-3.3WU - leave unconnected or float per datasheet guidance. |
| 5 - ON/OFF | Logic-controlled enable/disable input | Active-high: ≥2.4V = ON, ≤1.0V = OFF; pulls <30µA when active, enabling simple microcontroller or logic-level control. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external resistor divider, reducing BOM count and improving long-term voltage stability vs. adjustable variants. |
| Integrated 3A switch | Removes need for external MOSFET or transistor, simplifying layout and reducing footprint in space-constrained designs. |
| 52kHz fixed frequency | Enables predictable EMI profile and consistent inductor sizing across designs using industry-standard 330µH parts. |
| Thermal shutdown + current limit | Provides autonomous fault recovery without external monitoring circuitry - critical for unattended industrial equipment. |
| TO-263-5 package | Surface-mount form factor with exposed thermal pad supports automated assembly and higher power density than TO-220. |
Applications
| Industrial PLC I/O Module | Embedded Network Router |
|---|---|
|
Use Scenario: Powering 3.3V FPGA configuration memory, Ethernet PHY, and microcontroller in DIN-rail mounted PLC modules. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator converting 24V DC field bus to clean logic rail. Use Value: 75% efficiency at 3A reduces thermal load in sealed enclosures; TO-263 package allows compact double-sided PCB layout. |
Use Scenario: Generating 3.3V supply for ARM-based SoC, DDR memory, and Gigabit Ethernet controller in fanless edge routers. IC Role / Device Role / Timing Role: Main system regulator delivering stable 3.3V under dynamic load from packet processing bursts. Use Value: ±3% output tolerance ensures reliable boot and operation across temperature; ON/OFF pin enables firmware-controlled power cycling. |
| Automotive Body Control Unit | Medical Diagnostic Handheld |
|
Use Scenario: Converting 12V vehicle battery to regulated 3.3V for CAN transceivers, sensors, and MCU in BCM modules. IC Role / Device Role / Timing Role: Input-stage buck converter handling cold-crank (6V) to load-dump (40V) transients. Use Value: 4V–40V input range covers full automotive voltage envelope; thermal shutdown protects against under-hood overheating. |
Use Scenario: Providing isolated 3.3V rail for low-noise ADC front-end and Bluetooth LE radio in portable diagnostic devices. IC Role / Device Role / Timing Role: Efficient intermediate regulator stepping down from Li-ion battery or USB 5V input. Use Value: Low 200µA standby current extends battery life in sleep mode; fixed output avoids calibration drift in medical-grade sensing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2576-3.3T | Same electrical specs, but TO-220-5 through-hole package with higher θJA (65°C/W vs. 45°C/W for TO-263). | Requires manual soldering or wave soldering; less suitable for high-density SMT production. | Select LM2576-3.3T only if mechanical mounting or heatsink attachment favors through-hole format. |
| MP1584EN-LF-Z | 40V input, 3A, adjustable/fixed 3.3V option; 1.5MHz switching, smaller external components, but no built-in thermal shutdown burn-in test. | Better suited for compact consumer electronics; lacks Micrel's 100% thermal limit burn-in screening. | Choose MP1584EN-LF-Z when board area is constrained and higher frequency allows smaller magnetics - verify thermal margin independently. |
Compared with LM2576-3.3T, the LM2576-3.3WU offers superior thermal performance in SMT assembly; versus MP1584EN-LF-Z, it trades higher-frequency efficiency for proven ruggedness in industrial environments with verified thermal reliability screening.
Availability
LM2576-3.3WU is available at Aetrix Electronics and suitable for industrial automation, embedded networking, and automotive body electronics requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for LM2576-3.3WU 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
Micrel, Inc. was a U.S.-based analog and mixed-signal semiconductor company acquired by Microchip Technology in 2015, known for robust power management and timing solutions.
The LM2576 series was designed as a drop-in high-efficiency replacement for three-terminal linear regulators in industrial and embedded power systems, emphasizing simplicity, thermal resilience, and minimal external component count.
FAQ
What is the maximum input voltage rating for LM2576-3.3WU?
The absolute maximum input voltage for LM2576-3.3WU is 45V, but the recommended operating range is 4V to 40V DC. Exceeding 40V may trigger internal protection or reduce reliability; sustained operation above 40V voids specification guarantees. The LM2576-3.3WU maintains regulation and protection functionality across this full 4V–40V window under all load and temperature conditions.
Does LM2576-3.3WU require an external feedback resistor network?
No - LM2576-3.3WU is a fixed-output variant with internal feedback divider set for 3.3V, so pins 4 (FEEDBACK) is internally connected and must remain unconnected. Unlike adjustable versions such as LM2576ADJ, the LM2576-3.3WU eliminates resistor selection, placement, and tolerance errors, ensuring consistent 3.3V output without external tuning.
Can LM2576-3.3WU be used in a negative-output (inverting) configuration?
Yes - the LM2576-3.3WU can be configured as a positive-to-negative inverting buck-boost converter per Figure 11 in the Micrel datasheet, generating –3.3V from a positive input. This requires repositioning the inductor and diode, grounding the former OUTPUT pin, and using the former VIN pin as the negative output. The LM2576-3.3WU's internal switch and protection features remain fully functional in this topology.
What is the thermal resistance (θJA) of LM2576-3.3WU in typical PCB layout?
For LM2576-3.3WU in TO-263-5 package, θJA is 45°C/W when mounted on a PCB with ~1 square inch of copper surrounding the leads and thermal pad. This value assumes proper soldering of the exposed pad to a solid ground plane. Without adequate copper area, θJA degrades significantly - the LM2576-3.3WU's safe operating area depends critically on this layout implementation.
Is LM2576-3.3WU RoHS compliant?
Yes - LM2576-3.3WU is RoHS compliant per the manufacturer's ordering information, with exemption for "hot-melting solder" as noted in the datasheet. It contains no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above threshold limits, and is suitable for environmentally regulated industrial and medical product designs requiring RoHS certification.
LM2576-3.3WU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tube
- 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-263-5
LM2576-3.3WU FAQ
1.How can I place an order for LM2576-3.3WU through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2576-3.3WU 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 LM2576-3.3WU reliable?
The price and inventory of LM2576-3.3WU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2576-3.3WU is usually 5 days.
3.What payment methods are accepted for LM2576-3.3WU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2576-3.3WU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2576-3.3WU?
LM2576-3.3WU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2576-3.3WU 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 LM2576-3.3WU?
For technical support, including LM2576-3.3WU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2576-3.3WU requirements.
6.How does Aetrix verify that LM2576-3.3WU is sourced from the original manufacturer or authorized distributors?
All LM2576-3.3WU 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 LM2576-3.3WU meets industry standards.
7.What is the process for return or replacement of LM2576-3.3WU?
All LM2576-3.3WU units undergo pre-shipment inspection (PSI). If there is an issue with LM2576-3.3WU, 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 LM2576-3.3WU part is unused and in its original packaging.
Return procedure for LM2576-3.3WU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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