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Microchip Technology LM2575-3.3BU
- Part No.:
- LM2575-3.3BU
- Manufacturer:
- Microchip Technology
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LM2575-3.3BU.pdf
- Description:
- IC REG BUCK 3.3V 1A TO263-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,614
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Product details
Overview
LM2575-3.3BU from Micrel is a fixed-output 3.3V, 1A step-down (buck) switching regulator in TO-263 package, featuring 52kHz fixed-frequency operation, ±3% output voltage tolerance over line/load, and integrated thermal shutdown and cycle-by-cycle current limiting. It replaces linear regulators in power supplies for embedded controllers, industrial sensors, and telecom interface modules.
For engineers reviewing the LM2575-3.3BU datasheet, LM2575-3.3BU pinout, LM2575-3.3BU application, or LM2575-3.3BU equivalent, key selection criteria include input voltage range (4–40V), guaranteed 1A output, standby current <200µA, and compatibility with standard off-the-shelf inductors-critical for cost-sensitive, thermally constrained DC/DC designs.
Technical Context
The LM2575-3.3BU integrates a 52kHz oscillator, error amplifier with 1.23V internal reference, PWM comparator, and 1A NPN switch with saturation voltage ≤1.4V. Its feedback loop uses a fixed resistive divider to set 3.3V output, eliminating external resistor networks required by adjustable variants.
Thermal shutdown activates at TJ ≥150°C; current limit triggers at peak switch current ≥1.3A (min). The ON/OFF pin supports logic-level control with VIH ≥2.2V and IIL ≤10µA, enabling low-power system sequencing without external circuitry.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±3% over 0.2–1A load and 8–40V input - ensures stable MCU core supply without trimming. |
| Max Output Current | 1A continuous - supports single-rail microcontroller systems or FPGA I/O banks without derating. |
| Input Voltage Range | 4V to 40V - accommodates 5V, 12V, 24V, and 36V industrial bus rails with margin. |
| Switching Frequency | 52kHz ±10% - enables use of low-cost, high-saturation-current inductors (e.g., 330µH) and reduces EMI filtering complexity. |
| Efficiency | 75% at 12VIN/3.3VOUT/1A - cuts heat generation vs. linear regulators, often eliminating heatsinks. |
| Standby Current | <200µA when ON/OFF pin = 5V - enables low-power sleep modes in battery-backed systems. |
| Thermal Protection | Internal shutdown at 150°C junction temperature - prevents failure during overload or poor airflow conditions. |
Pinout & Package
LM2575-3.3BU uses a 5-pin TO-263 (D2Pak) surface-mount package with exposed tab for thermal conduction. Pin 1: VIN, Pin 2: OUTPUT, Pin 3: GND, Pin 4: FEEDBACK (internally connected to 3.3V divider), Pin 5: ON/OFF.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Unregulated input supply connection | Accepts 4–40V DC; requires local 100µF input capacitor to suppress switching transients. |
| 2 (OUTPUT) | Switched output node | Drives external catch diode and inductor; peak current capability up to 1A with ≤1.4V saturation drop. |
| 3 (GND) | Power and signal ground reference | Must be low-impedance connection to minimize noise coupling into feedback path. |
| 4 (FEEDBACK) | Regulation sense input | Internally tied to fixed 3.3V divider; no external resistors needed - simplifies layout and improves stability. |
| 5 (ON/OFF) | Logic-controlled enable/disable | Active-low control: ≤0.8V = ON, ≥2.2V = OFF; draws ≤10µA in active state. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external feedback resistors - reduces BOM count, layout area, and calibration risk. |
| Integrated current limit & thermal shutdown | Self-protecting under short-circuit or overheating - avoids need for external fault management circuitry. |
| 52kHz fixed-frequency oscillator | Enables predictable EMI spectrum and consistent inductor sizing across designs. |
| Low quiescent current in standby | <200µA shutdown current - extends battery life in always-on monitoring nodes. |
| TO-263 thermal package | Exposed tab allows direct PCB copper pour attachment - achieves θJA ≈ 45°C/W with 4 in² copper, reducing thermal design effort. |
Applications
| Industrial Sensor Node Power | Embedded Controller Core Supply |
|---|---|
Use Scenario: Powering 3.3V microcontrollers and analog sensor front-ends in factory-floor temperature/humidity monitors with 24V DC input. IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated 3.3V rail with line/load regulation ≤±3% across wide ambient temperature range. Use Value: Replaces inefficient 78L33 linear regulator, reducing board temperature rise by >25°C at full load and eliminating heatsink requirements. | Use Scenario: Generating stable 3.3V supply for ARM Cortex-M4-based motor control boards powered from 12V vehicle battery. IC Role / Device Role / Timing Role: Step-down converter with ON/OFF pin controlled by MCU GPIO to sequence power-up and enter deep-sleep mode. Use Value: Achieves 75% efficiency at 1A, cutting power loss to 1.1W vs. 2.4W for linear solution - critical for sealed enclosure thermal management. |
| Telecom Interface Module | Programmable Logic I/O Bank |
Use Scenario: Providing clean 3.3V rail to RS-485 transceivers and isolation buffers in network edge gateways operating from 48V PoE-derived input. IC Role / Device Role / Timing Role: Pre-regulator feeding low-noise LDOs; handles wide input variation (36–57V via external Zener clamp) while maintaining tight output tolerance. Use Value: With 4–40V input range and ±3% output accuracy, maintains valid logic levels across PoE Class 3–8 voltage tolerances without additional regulation stages. | Use Scenario: Supplying configurable I/O banks on Xilinx Spartan-7 FPGA development boards using 12V wall adapter input. IC Role / Device Role / Timing Role: High-current buck stage delivering 3.3V at up to 1A to support multiple parallel I/O standards (LVCMOS, SSTL). Use Value: Integrated 1A switch and thermal protection prevent brownouts during simultaneous I/O switching events - improving signal integrity and timing margin. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2575-3.3WU | Same electrical specs; RoHS-compliant "high-melting solder" exemption version in identical TO-263 package. | No functional difference; selected where lead-free assembly with Sn96.5/Ag3.0/Cu0.5 solder is mandated. | Direct replacement if RoHS compliance with exemption is required; same thermal and electrical behavior. |
| MP1584EN-LF-Z | Higher 1.5MHz switching frequency, 3A output, but requires external feedback resistors and has different pinout (SOIC-8). | Enables smaller magnetics and capacitors but increases design complexity and layout sensitivity. | Choose for space-constrained designs needing higher current or faster transient response; not pin-compatible. |
Compared with LM2575-3.3WU, the LM2575-3.3BU offers identical performance with standard Pb-based solder compatibility; versus MP1584EN-LF-Z, it trades higher integration and lower EMI for lower frequency operation and simpler external component count - favoring robustness over miniaturization.
Availability
LM2575-3.3BU is available at Aetrix Electronics and suitable for industrial automation, embedded computing, and telecom infrastructure requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LM2575-3.3BU 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 specializing in power management, timing, and interface ICs before its acquisition by Microchip Technology in 2015.
The LM2575 series was designed as a monolithic, easy-to-use buck regulator family targeting cost-sensitive, thermally constrained applications where simplicity and reliability outweigh ultra-high efficiency or miniaturization.
FAQ
What is the maximum input voltage rating for the LM2575-3.3BU?
The LM2575-3.3BU has an absolute maximum input voltage of 45V, with recommended operating range up to 40V. Exceeding 40V risks violating the device's safe operating area, especially under high ambient temperatures or heavy load. The LM2575-3.3BU must be used with appropriate input transient suppression (e.g., TVS diode) when deployed in automotive or industrial environments with load-dump events.
Does the LM2575-3.3BU require external feedback resistors to set its output voltage?
No, the LM2575-3.3BU does not require external feedback resistors. Its 3.3V output is internally trimmed and fixed; the FEEDBACK pin (Pin 4) is pre-connected to an internal resistive divider. This eliminates resistor tolerance errors and layout sensitivity, making the LM2575-3.3BU simpler to implement than adjustable variants like the LM2575-ADJ.
Can the LM2575-3.3BU be used in a negative-output (inverting) configuration?
Yes, the LM2575-3.3BU can be configured as a negative-output buck-boost converter by repositioning the inductor and diode per Micrel Application Note AN-12. In this topology, the LM2575-3.3BU generates –3.3V from a positive input, retaining its 52kHz switching frequency and built-in protections. However, output current capability drops to ~700mA due to duty-cycle limitations and diode forward-voltage losses.
What is the thermal resistance (θJA) of the LM2575-3.3BU in typical PCB layout?
The LM2575-3.3BU in TO-263 package achieves θJA ≈ 45°C/W when mounted on a PCB with ~4 square inches of 2-oz copper connected to the exposed tab. Without copper pour, θJA rises to ~85°C/W. For reliable 1A operation at +85°C ambient, the LM2575-3.3BU requires at least 2 in² of thermal copper to keep junction temperature below 125°C.
How does the ON/OFF pin function on the LM2575-3.3BU?
The ON/OFF pin (Pin 5) of the LM2575-3.3BU provides logic-level enable control: driving it ≤0.8V (relative to GND) turns the regulator ON; pulling it ≥2.2V disables switching and reduces quiescent current to <200µA. The LM2575-3.3BU draws only ≤10µA through this pin in active state, allowing direct interfacing with 3.3V or 5V microcontroller GPIOs without level-shifting.
LM2575-3.3BU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Bulk
- 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:
- 1A
- 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
LM2575-3.3BU FAQ
1.How can I place an order for LM2575-3.3BU through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2575-3.3BU 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 LM2575-3.3BU reliable?
The price and inventory of LM2575-3.3BU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2575-3.3BU is usually 5 days.
3.What payment methods are accepted for LM2575-3.3BU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2575-3.3BU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2575-3.3BU?
LM2575-3.3BU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2575-3.3BU 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 LM2575-3.3BU?
For technical support, including LM2575-3.3BU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2575-3.3BU requirements.
6.How does Aetrix verify that LM2575-3.3BU is sourced from the original manufacturer or authorized distributors?
All LM2575-3.3BU 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 LM2575-3.3BU meets industry standards.
7.What is the process for return or replacement of LM2575-3.3BU?
All LM2575-3.3BU units undergo pre-shipment inspection (PSI). If there is an issue with LM2575-3.3BU, 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 LM2575-3.3BU part is unused and in its original packaging.
Return procedure for LM2575-3.3BU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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