Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

Microchip Technology LM2575-3.3WU

Name: LM2575-3.3WU
Brand: Microchip Technology
SKU: LM2575-3.3WU
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: LM2575-3.3WU

Manufacturer:: Microchip Technology

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: TO-263-6, D2PAK (5 Leads + Tab), TO-263BA

Datasheet:: LM2575-3.3WU.pdf

Description:: IC REG BUCK 3.3V 1A TO263-5

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:1,519

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

LM2575-3.3WU 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 load and line, integrated thermal shutdown and cycle-by-cycle current limiting, and <200µA standby current. It replaces linear regulators in power supplies for embedded microcontrollers, industrial sensors, and point-of-load DC/DC conversion.

For engineers reviewing the LM2575-3.3WU datasheet, LM2575-3.3WU pinout, LM2575-3.3WU application, or LM2575-3.3WU equivalent, key selection criteria include guaranteed 1A output at 3.3V with 4V–40V input range, TO-263 thermal performance (θ_JA = 45°C/W with 4 in² copper), and compatibility with standard off-the-shelf 330µH inductors and Schottky catch diodes.

Technical Context

The LM2575-3.3WU integrates a 52kHz oscillator, error amplifier, bandgap reference (1.23V), PWM comparator, and 1A NPN switch with built-in current limit and thermal shutdown. Its feedback loop is internally compensated, requiring only four external components: input capacitor, output capacitor, inductor, and catch diode.

It operates in continuous conduction mode with up to 98% maximum duty cycle and 0.9V typical saturation voltage at 1A. The ON/OFF pin enables logic-controlled shutdown with <200µA quiescent current, and the fixed 3.3V output eliminates external resistor divider requirements.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 3.3V ±3% over 0.2A–1A load and 8V–40V input ensures stable MCU core supply without trimming.
Max Output Current	1A continuous - supports single-core ARM Cortex-M or FPGA I/O banks without derating at 25°C ambient.
Input Voltage Range	4V to 40V - accommodates 5V, 12V, 24V, and 36V industrial rails with dropout margin.
Switching Frequency	52kHz ±10% - enables use of low-cost, high-saturation-current toroidal inductors (e.g., 330µH) with minimal EMI filtering.
Efficiency	75% at 12V_IN/3.3V_OUT/1A - reduces thermal load vs. linear regulators; no heatsink required below 0.5A at 25°C.
Quiescent Current	<200µA in shutdown - enables battery-backed systems to maintain >1-year shelf life with coin-cell backup.
Thermal Resistance	θ_JA = 45°C/W (with 4 in² PCB copper) - allows full 1A operation up to +85°C ambient without forced air.

Pinout & Package

LM2575-3.3WU uses a 5-pin TO-263 (D²Pak) surface-mount package with exposed thermal pad. Pin 1 is VIN, Pin 2 is OUTPUT, Pin 3 is GND, Pin 4 is FEEDBACK (internally tied to 3.3V regulation node), and Pin 5 is ON/OFF. The tab is electrically connected to Pin 3 (GND) and serves as primary thermal path.

Pin/Terminal	Circuit Role	Design Meaning
1 - VIN	Unregulated input supply connection	Accepts 4V–40V DC; requires ≥100µF bulk capacitance near pin to suppress switching transients.
2 - OUTPUT	Switched output node driving inductor	Connects to inductor input; carries pulsed 1A current; layout must minimize trace inductance to reduce ringing.
3 - GND	Power and signal ground reference	Common return for input cap, output cap, and catch diode; must tie directly to thermal pad for thermal integrity.
4 - FB	Feedback input (internal 3.3V reference)	Internally connected to regulated 3.3V output; no external resistors needed - simplifies layout and improves stability.
5 - ON/OFF	Logic-level enable/disable control	Drives internal regulator into <200µA standby when pulled ≥2.2V; ≤0.8V enables normal operation.

Key Features

Feature	Design Value
Fixed 3.3V output	Eliminates external feedback resistors - reduces BOM count, layout area, and calibration drift over temperature.
Integrated protection	Cycle-by-cycle current limiting and thermal shutdown prevent damage during short-circuit or overload conditions without external circuitry.
Low-component-count design	Only four external parts required (C_IN, L, D_catch, C_OUT) - accelerates prototyping and lowers manufacturing defect risk.
TO-263 thermal performance	45°C/W junction-to-ambient (with 4 in² copper) enables 1A operation at +85°C ambient - suitable for enclosed industrial enclosures.
52kHz switching frequency	Enables use of low-DCR, high-current inductors with minimal core loss - avoids audible noise and simplifies EMI filter design.

Applications

Industrial PLC I/O Modules	Embedded Microcontroller Power
Use Scenario: Providing clean 3.3V rail for digital I/O expansion cards in programmable logic controllers operating from 24V DC field bus. IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 3.3V to isolated SPI/I²C peripherals and level-shifted GPIO drivers. Use Value: Replaces inefficient 78L33 linear regulator; eliminates heatsink while maintaining <±1% output ripple under 1A dynamic load steps.	Use Scenario: Powering ARM Cortex-M4 microcontrollers and associated flash memory in battery-backed data loggers. IC Role / Device Role / Timing Role: Main system regulator converting 12V vehicle or solar input to 3.3V core voltage with ON/OFF controlled by MCU wake signal. Use Value: Achieves 75% efficiency at full load and <200µA shutdown current - extends lithium-thionyl chloride battery life beyond 3 years.
Point-of-Load Converters	Industrial Sensor Transmitters
Use Scenario: Local 3.3V generation on dense PCBs where centralized 5V supply is available but remote loads require low-noise 3.3V. IC Role / Device Role / Timing Role: Compact, self-contained buck stage placed adjacent to FPGA or ADC to minimize IR drop and noise coupling. Use Value: TO-263 package with thermal pad delivers 1A with <15°C rise above ambient - avoids thermal throttling in multi-layer boards.	Use Scenario: Powering 4–20mA loop-powered temperature and pressure transmitters with wide input range (7–36V). IC Role / Device Role / Timing Role: Efficient pre-regulator stepping down loop voltage to 3.3V for sensor signal conditioning and low-power MCU. Use Value: Operates down to 4V input - maintains regulation even during brownout events common in long-loop wiring.

Industrial PLC I/O Modules

Embedded Microcontroller Power

Use Scenario: Providing clean 3.3V rail for digital I/O expansion cards in programmable logic controllers operating from 24V DC field bus.

IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 3.3V to isolated SPI/I²C peripherals and level-shifted GPIO drivers.

Use Value: Replaces inefficient 78L33 linear regulator; eliminates heatsink while maintaining <±1% output ripple under 1A dynamic load steps.

Use Scenario: Powering ARM Cortex-M4 microcontrollers and associated flash memory in battery-backed data loggers.

IC Role / Device Role / Timing Role: Main system regulator converting 12V vehicle or solar input to 3.3V core voltage with ON/OFF controlled by MCU wake signal.

Use Value: Achieves 75% efficiency at full load and <200µA shutdown current - extends lithium-thionyl chloride battery life beyond 3 years.

Point-of-Load Converters

Industrial Sensor Transmitters

Use Scenario: Local 3.3V generation on dense PCBs where centralized 5V supply is available but remote loads require low-noise 3.3V.

IC Role / Device Role / Timing Role: Compact, self-contained buck stage placed adjacent to FPGA or ADC to minimize IR drop and noise coupling.

Use Value: TO-263 package with thermal pad delivers 1A with <15°C rise above ambient - avoids thermal throttling in multi-layer boards.

Use Scenario: Powering 4–20mA loop-powered temperature and pressure transmitters with wide input range (7–36V).

IC Role / Device Role / Timing Role: Efficient pre-regulator stepping down loop voltage to 3.3V for sensor signal conditioning and low-power MCU.

Use Value: Operates down to 4V input - maintains regulation even during brownout events common in long-loop wiring.

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2575-3.3T	Same electrical specs, but in 5-pin TO-220 package with θ_JA = 65°C/W (no PCB copper dependency); requires mechanical mounting and heatsink above ~0.6A.	Suitable for through-hole prototyping or low-volume assemblies where manual soldering is preferred.	Select LM2575-3.3T if board assembly uses wave soldering or requires vertical heatsink attachment; avoid for high-density SMT production.
MP1584EN-LF-Z	Higher 1.5MHz switching frequency, 3A rating, ±2% output accuracy, but requires external compensation and 6 external components.	Better suited for space-constrained designs needing smaller inductors, but increases design complexity and cost.	Choose MP1584EN-LF-Z only when footprint reduction outweighs BOM simplicity; LM2575-3.3WU remains optimal for robust, low-risk 1A designs.

Compared with LM2575-3.3T, LM2575-3.3WU offers superior thermal performance in SMT layouts and eliminates mechanical fasteners; compared with MP1584EN-LF-Z, it trades higher frequency for proven stability, lower component count, and reduced validation effort in industrial environments.

Availability

LM2575-3.3WU is available at Aetrix Electronics and suitable for industrial automation, embedded computing, and sensor transmitter applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LM2575-3.3WU 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 headquartered in San Jose, CA, specializing in power management, timing, and interface ICs before its acquisition by Microchip Technology in 2015.

The LM2575 series was designed as a drop-in, high-efficiency replacement for three-terminal linear regulators in industrial and embedded power supplies - prioritizing simplicity, reliability, and thermal robustness over ultra-high frequency or digital control.

FAQ

What is the minimum input voltage required for LM2575-3.3WU to regulate 3.3V output?

The LM2575-3.3WU requires a minimum input voltage of 4V to maintain regulation. This accounts for internal saturation voltage (~0.9V at 1A) and control headroom. Below 4V, the device enters dropout and output voltage drops linearly with input - verified across –40°C to +85°C per datasheet Section 4.

Can LM2575-3.3WU be used with ceramic output capacitors?

Yes, LM2575-3.3WU supports ceramic output capacitors, but requires ≥30mΩ ESR for loop stability due to its internal compensation. A 330µF aluminum electrolytic (typical ESR ~35mΩ) is recommended; if using ceramics, add a 33mΩ damping resistor in series with the capacitor to meet stability requirements.

Does LM2575-3.3WU require an external diode, and what type is specified?

Yes, LM2575-3.3WU requires an external Schottky catch diode (e.g., MBR360 or 1N5822) connected between OUTPUT and GND. The diode must handle ≥1A average current and ≥30V reverse voltage; Schottky type is mandatory to minimize forward voltage drop and preserve efficiency.

What is the thermal performance difference between LM2575-3.3WU and LM2575-3.3T?

LM2575-3.3WU (TO-263) achieves θ_JA = 45°C/W with 4 in² PCB copper, enabling full 1A operation at +85°C ambient. LM2575-3.3T (TO-220) has θ_JA = 65°C/W with no copper, requiring a heatsink above ~0.6A - confirmed by Micrel's Package Information tables on page 11.

Is LM2575-3.3WU RoHS compliant, and what exemption applies?

Yes, LM2575-3.3WU is RoHS compliant with the "high-melting solder" exemption (EU Directive 2011/65/EU Annex III), as noted in the Ordering Information table on page 2. This permits lead content necessary for reliable high-temperature reflow of the TO-263 package.

LM2575-3.3WU 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:: 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

LM2575-3.3WU FAQ

1.How can I place an order for LM2575-3.3WU through Aetrix?

Please submit a Request for Quotation (RFQ) for LM2575-3.3WU 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 LM2575-3.3WU reliable?

The price and inventory of LM2575-3.3WU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2575-3.3WU is usually 5 days.

3.What payment methods are accepted for LM2575-3.3WU?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2575-3.3WU transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LM2575-3.3WU?

LM2575-3.3WU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LM2575-3.3WU 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 LM2575-3.3WU?

For technical support, including LM2575-3.3WU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2575-3.3WU requirements.

6.How does Aetrix verify that LM2575-3.3WU is sourced from the original manufacturer or authorized distributors?

All LM2575-3.3WU 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 LM2575-3.3WU meets industry standards.

7.What is the process for return or replacement of LM2575-3.3WU?

All LM2575-3.3WU units undergo pre-shipment inspection (PSI). If there is an issue with LM2575-3.3WU, 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 LM2575-3.3WU part is unused and in its original packaging.

Return procedure for LM2575-3.3WU:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…