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Microchip Technology LM2576BU TR
- Part No.:
- LM2576BU TR
- Manufacturer:
- Microchip Technology
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2576BU TR.pdf
- Description:
- IC REG BUCK ADJ 3A TO263-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,909
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Product details
Overview
LM2576BU TR from Micrel is an adjustable 3A step-down (buck) DC-DC switching regulator in TO-263-5 package, operating at a fixed 52kHz switching frequency with input voltage range 4V–40V and output voltage programmable from 1.23V to 37V. It delivers ±2% feedback voltage accuracy, integrated thermal shutdown and cycle-by-cycle current limiting, and is commonly used in industrial power supplies and embedded system pre-regulators.
For engineers reviewing the LM2576BU TR datasheet, LM2576BU TR pinout, LM2576BU TR application, or LM2576BU TR equivalent, key selection criteria include guaranteed 3A output current, 52kHz fixed-frequency operation, TO-263 thermal performance (θJA = 45°C/W with 1 in² copper), and compatibility with standard off-the-shelf inductors for rapid design implementation.
Technical Context
The LM2576BU TR integrates a 3A NPN switch, 1.23V bandgap reference, error amplifier, 52kHz oscillator, and thermal/current protection circuitry. Its fixed-frequency PWM control uses internal frequency compensation and requires only four external components - input capacitor, output capacitor, catch diode, and inductor - to form a complete buck regulator.
Feedback is sensed at the FB pin (Pin 4), referenced to the internal 1.23V precision reference; output voltage is set by an external resistor divider. The ON/OFF pin (Pin 5) enables low-quiescent standby mode (<200µA), and the device enters thermal shutdown if junction temperature exceeds 150°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Guaranteed 3A continuous load capability - supports high-current rails without external pass devices. |
| Input Voltage Range | 4V to 40V - accommodates wide-input industrial and automotive battery-supplied systems. |
| Output Voltage Range | 1.23V to 37V (adjustable via resistor divider) - enables flexible rail generation across analog, digital, and mixed-signal subsystems. |
| Switching Frequency | 52kHz ±10% - balances EMI control, inductor size, and efficiency; compatible with low-cost, high-saturation-current inductors. |
| Feedback Accuracy | ±2% over full temperature and load range - ensures stable regulation without trimming or calibration. |
| Quiescent Current | <200µA in standby (ON/OFF pin high) - minimizes power loss in always-on or low-power wake-up circuits. |
| Thermal Protection | Internal thermal shutdown at TJ ≥ 150°C - prevents damage during overload or poor heatsinking conditions. |
Pinout & Package
LM2576BU TR is housed in a surface-mount 5-lead TO-263 (D2Pak) package with exposed thermal pad for enhanced heat dissipation. Thermal resistance is θJA = 45°C/W with ~1 in² PCB copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Input supply connection | Accepts unregulated DC input (4V–40V); must be decoupled with ≥100µF electrolytic capacitor. |
| 2 - OUTPUT | Switch node / power output | Drives external inductor; carries pulsed 3A current - requires low-inductance routing and Schottky catch diode. |
| 3 - GND | Power ground reference | Common return for input cap, output cap, and feedback network; must connect directly to thermal pad. |
| 4 - FEEDBACK | Voltage sense input | Monitors output via resistor divider; internal 1.23V reference sets VOUT = 1.23V × (1 + R2/R1). |
| 5 - ON/OFF | Enable/disable control | Logic-high (>2.2V) disables regulator (IQ < 200µA); logic-low (<1.0V) enables operation. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 52kHz oscillator | Eliminates need for external timing components and simplifies EMI filtering design. |
| Integrated current limit & thermal shutdown | Provides autonomous fault protection without external sensing circuitry or shutdown controllers. |
| Only 4 external components required | Reduces BOM count, layout area, and design validation effort versus discrete switcher solutions. |
| TO-263 thermal performance | 45°C/W junction-to-ambient (with 1 in² copper) enables 3A operation without heatsink in many applications. |
| ±2% feedback voltage tolerance | Ensures tight output regulation across temperature and line/load variations without post-production trimming. |
Applications
| Industrial Power Supplies | Embedded System Pre-regulators |
|---|---|
|
Use Scenario: Converting 24V DC bus to 5V/3.3V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, efficient intermediate rail generation. Use Value: Delivers 3A at >80% efficiency with minimal thermal rise on standard FR4, reducing need for forced air cooling. |
Use Scenario: Generating stable 3.3V from 12V vehicle battery for microcontroller and CAN transceiver rails. IC Role / Device Role / Timing Role: High-reliability step-down regulator with wide input range and built-in fault protection. Use Value: Withstands cold-crank (4V) and load-dump (40V) transients while maintaining regulated output via internal protection. |
| On-Card Switching Supplies | Positive-to-Negative Converters |
|
Use Scenario: Local 12V-to-5V conversion on dense PCBs where space and thermal management are constrained. IC Role / Device Role / Timing Role: Compact, self-contained buck controller enabling point-of-load regulation. Use Value: TO-263 package allows direct thermal coupling to PCB copper, achieving 3A output without discrete heatsink. |
Use Scenario: Generating –5V from +12V for op-amp biasing or RS-232 interface circuitry. IC Role / Device Role / Timing Role: Configured as inverting buck-boost converter using standard external components. Use Value: Leverages same 52kHz oscillator and current-limit architecture - no redesign needed beyond topology change. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2576T-5.0 | Fixed 5V output; TO-220-5 package; higher θJA (65°C/W) | Eliminates feedback resistors but lacks output flexibility; requires heatsink above ~1.5A | Select when 5V output is fixed and through-hole assembly is preferred. |
| MP1584EN-LF-Z | 3A, 1.5MHz switching; SOIC-8; requires external compensation | Enables smaller magnetics and lower output ripple, but demands more design validation effort | Select when board space is critical and higher-frequency operation justifies added complexity. |
Compared with LM2576T-5.0, the LM2576BU TR offers adjustable output and superior thermal performance on PCB; compared with MP1584EN-LF-Z, it trades higher frequency for simpler design, proven reliability, and reduced EMI filter burden.
Availability
LM2576BU TR is available at Aetrix Electronics and suitable for industrial power supplies, embedded system pre-regulators, and on-card switching regulators requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.
Supply support for LM2576BU TR 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 semiconductor company specializing in power management, analog, and RF ICs before its acquisition by Microchip Technology in 2015. Known for robust, application-ready power solutions.
The LM2576 series was designed as a drop-in high-efficiency replacement for linear regulators in medium-power DC-DC conversion, targeting cost-sensitive industrial and embedded applications where simplicity and reliability were paramount.
FAQ
What is the maximum input voltage rating for the LM2576BU TR?
The LM2576BU TR has an absolute maximum input voltage of 45V, with recommended continuous operation up to 40V. Exceeding 40V risks violating the specified operating ratings and may trigger internal protection or reduce long-term reliability. The LM2576BU TR is rated for 4V–40V input under normal conditions, making it suitable for 24V industrial buses and automotive applications with transient tolerance.
Does the LM2576BU TR require an external diode, and what type is recommended?
Yes, the LM2576BU TR requires an external Schottky catch diode connected between the OUTPUT (Pin 2) and GND (Pin 3). A 3A-rated Schottky diode such as MBR360 or 1N5822 is recommended to minimize forward voltage drop and switching losses. The LM2576BU TR does not integrate a synchronous rectifier, so diode selection directly impacts efficiency and thermal performance at full load.
Can the LM2576BU TR be used in a negative-output (inverting) configuration?
Yes, the LM2576BU TR can be configured as a positive-to-negative inverting buck-boost converter using the standard application circuit shown in the datasheet. In this topology, the GND pin becomes the negative output rail, and the OUTPUT pin connects to the inductor. The LM2576BU TR maintains its 3A switch current capability and 52kHz operation, though output voltage regulation accuracy depends on external component tolerances.
What is the thermal resistance (θJA) of the LM2576BU TR under typical PCB layout conditions?
The LM2576BU TR has a junction-to-ambient thermal resistance (θJA) of 45°C/W when mounted on a PCB with approximately 1 in² of copper area surrounding the leads and thermal pad. This value assumes standard FR4 material and no external heatsink. With adequate copper pour, the LM2576BU TR can sustain 3A output at ambient temperatures up to +70°C without additional cooling.
How does the ON/OFF pin function on the LM2576BU TR, and what are its voltage thresholds?
The ON/OFF pin (Pin 5) of the LM2576BU TR enables hardware-controlled shutdown: applying ≤0.8V (max) turns the regulator on, while ≥2.2V (min) places it in standby mode with quiescent current <200µA. The pin draws <30µA in OFF state and <10µA in ON state. This feature allows the LM2576BU TR to support low-power sleep modes in battery-powered or energy-conscious systems.
LM2576BU TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- 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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 37V
- 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
LM2576BU TR FAQ
1.How can I place an order for LM2576BU TR through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2576BU TR 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 LM2576BU TR reliable?
The price and inventory of LM2576BU TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2576BU TR is usually 5 days.
3.What payment methods are accepted for LM2576BU TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2576BU TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2576BU TR?
LM2576BU TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2576BU TR 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 LM2576BU TR?
For technical support, including LM2576BU TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2576BU TR requirements.
6.How does Aetrix verify that LM2576BU TR is sourced from the original manufacturer or authorized distributors?
All LM2576BU TR 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 LM2576BU TR meets industry standards.
7.What is the process for return or replacement of LM2576BU TR?
All LM2576BU TR units undergo pre-shipment inspection (PSI). If there is an issue with LM2576BU TR, 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 LM2576BU TR part is unused and in its original packaging.
Return procedure for LM2576BU TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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