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Texas Instruments LM2574M-3.3
- Part No.:
- LM2574M-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LM2574M-3.3.pdf
- Description:
- IC REG BUCK 3.3V 500MA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,187
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Product details
Overview
LM2574M-3.3 from Texas Instruments (formerly National Semiconductor) is a monolithic 0.5A step-down (buck) switching voltage regulator in fixed 3.3V output configuration, housed in a 14-pin wide-body surface-mount package (M14B). It delivers ±4% output voltage accuracy over line and load, operates from 4.75V–40V input, features 52 kHz fixed-frequency internal oscillator, cycle-by-cycle current limiting, thermal shutdown, and TTL-compatible shutdown with 50 µA standby current - used in embedded power rails for microcontrollers and FPGAs.
For engineers reviewing the LM2574M-3.3 datasheet, LM2574M-3.3 pinout, LM2574M-3.3 application, or LM2574M-3.3 equivalent, key selection criteria include guaranteed 0.5A output current, 3.3V fixed output with tight tolerance, wide 4.75–40V input range, minimal external component count (only 4 required), and compatibility with standard off-the-shelf inductors - critical for industrial DC-DC conversion where thermal performance and layout simplicity matter.
Technical Context
The LM2574M-3.3 integrates a PWM controller, power switch, oscillator, error amplifier, and protection circuitry into a single IC. Its fixed-frequency 52 kHz operation enables predictable EMI filtering and stable loop compensation without external frequency-setting components. Internal current limiting and thermal shutdown provide fault resilience during overload or ambient temperature excursions up to +125°C junction.
It uses a buck topology with external catch diode, inductor, and input/output capacitors. The feedback path is internally connected to the 3.3V output node, eliminating external resistor dividers. Shutdown control is implemented via a dedicated ON/OFF pin accepting TTL-level logic, enabling low-quiescent-power sequencing in multi-rail systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±4% over full operating temperature (−40°C to +125°C) and load (0.1–0.5A) |
| Max Output Current | 0.5A DC continuous - sufficient to power ARM Cortex-M series MCUs or small FPGA I/O banks |
| Input Voltage Range | 4.75V to 40V - supports 5V, 12V, 24V industrial bus inputs without pre-regulation |
| Switching Frequency | 52 kHz fixed - enables use of low-cost, high-saturation-current inductors (e.g., 330 µH) and simplifies EMI filter design |
| Efficiency | 72% at VIN = 12V, IOUT = 0.5A - reduces thermal load vs. linear regulators; PCB copper acts as primary heatsink |
| Standby Current | 50 µA typical at shutdown - enables battery-backed systems to maintain ultra-low sleep power |
| Thermal Resistance | 78°C/W (junction-to-ambient, 4-in² copper) - defines minimum PCB copper area needed for safe 0.5A operation at +85°C ambient |
Pinout & Package
LM2574M-3.3 is packaged in a 14-pin wide-body surface-mount (WM) package (NS package code M14B), optimized for thermal dissipation on standard FR-4 PCBs with extended copper pour.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7 | GND | Power and signal ground - must be connected to large low-impedance copper plane for thermal and noise control |
| 8 | ON/OFF | TTL-compatible enable input - pulled high internally; drives <10 µA; 0V = active, >2.2V = shutdown |
| 9 | OUTPUT | Switching node - connects to inductor and catch diode anode; carries pulsed 0.5A current |
| 10 | VIN | Main power input - accepts 4.75–40V; requires local 22 µF electrolytic bypass capacitor |
| 11 | GND | Dedicated power ground return for VIN bypass - separate from signal GND pins to reduce noise coupling |
| 12 | FEEDBACK | Internally tied to 3.3V output - no external resistors required; not accessible in fixed-output version |
| 13 | GND | Additional power ground - enhances thermal conduction and reduces ground bounce |
| 14 | GND | Thermal pad connection - soldered directly to PCB copper for optimal heat transfer (not electrically isolated) |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external feedback resistors - reduces BOM count, layout area, and calibration drift over temperature |
| Internal 52 kHz oscillator | Removes need for timing capacitor/resistor - improves production consistency and eliminates oscillator drift-related instability |
| Cycle-by-cycle current limit | Protects against short-circuit and overload without latch-up - maintains regulation during transient faults |
| TTL shutdown interface | Enables precise power sequencing in multi-voltage systems with <10 µA control current draw |
| Thermal shutdown | Auto-recovers after cooling - prevents permanent damage during sustained overload or poor heatsinking |
Applications
| Industrial PLC I/O Power | Embedded MCU Core Rail |
|---|---|
Use Scenario: Providing clean 3.3V power to digital I/O modules in programmable logic controllers operating from 24V DC field buses. IC Role / Device Role / Timing Role: Primary step-down regulator converting unregulated 24V supply to stable 3.3V for isolation buffers, level translators, and status LEDs. Use Value: High efficiency (≥70% at 24V→3.3V/0.3A) minimizes heat buildup in sealed enclosures; wide input range accommodates bus voltage sag and ripple. | Use Scenario: Powering ARM Cortex-M4 microcontrollers and associated peripherals in edge sensor nodes with battery or solar backup. IC Role / Device Role / Timing Role: Main system regulator delivering 3.3V to MCU VDD, ADC reference, and communication interfaces (UART, SPI). Use Value: 50 µA shutdown current extends battery life in sleep mode; fixed output ensures consistent reset behavior and clock stability. |
| Medical Instrument Front-End | Test Equipment Auxiliary Supply |
Use Scenario: Generating isolated 3.3V rail for analog front-end amplifiers and data acquisition circuits in portable diagnostic devices. IC Role / Device Role / Timing Role: Pre-regulator feeding low-noise LDOs that supply precision ADCs and op-amps. Use Value: Low output voltage tolerance (±4%) ensures accurate sensor scaling; thermal shutdown prevents malfunction during extended bench operation. | Use Scenario: On-board 3.3V supply for FPGA configuration memory and JTAG debug interfaces in automated test equipment. IC Role / Device Role / Timing Role: Secondary regulator supporting non-critical logic rails independent of main 5V/12V system supplies. Use Value: Minimal external parts (4 total) accelerate prototype iteration; 14-pin WM package allows dense board layouts without through-hole constraints. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2575M-3.3 | Higher 1A output current; 52 kHz frequency; requires same external components but larger inductor (100 µH vs. 330 µH for LM2574) | Better suited for higher-load applications (e.g., multi-peripheral MCU systems); slightly lower efficiency at light loads due to higher quiescent current | Select when >0.5A output is required and board space allows larger inductor footprint |
| TPS54302DDCR | 3A synchronous buck; 2.5–6V input; integrated high-side/low-side MOSFETs; 2.5 MHz switching; requires fewer external parts | Designed for compact, high-efficiency point-of-load regulation; incompatible with 12V+ inputs; needs careful layout for EMI control at high frequency | Choose for space-constrained designs needing >0.5A and input <6V; not suitable as direct replacement for 24V bus applications |
Compared with LM2575M-3.3 and TPS54302DDCR, the LM2574M-3.3 offers optimal balance of ruggedness, simplicity, and wide-input capability - ideal for industrial 12–24V systems where reliability and minimal BOM outweigh peak current or size requirements.
Availability
LM2574M-3.3 is available at Aetrix Electronics and suitable for industrial automation, embedded computing, and medical instrumentation requiring stable component supply across long product lifecycles and varying environmental conditions.
Supply support for LM2574M-3.3 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 acquired National Semiconductor in 2011 and maintains full technical and manufacturing continuity for the SIMPLE SWITCHER™ product line.
The LM2574M-3.3 belongs to TI's SIMPLE SWITCHER™ family of integrated buck regulators, designed specifically for robust, low-component-count DC-DC conversion in harsh industrial and automotive-adjacent environments.
FAQ
What is the maximum input voltage rating for LM2574M-3.3?
The LM2574M-3.3 has an absolute maximum input voltage of 45V and a recommended operating maximum of 40V. Exceeding 40V risks violating the device's guaranteed electrical specifications, especially under high-temperature conditions. For applications requiring >40V input, the LM2574HV-3.3 variant (60V operating max) should be selected instead. Always observe derating curves in the official TI datasheet DS011394 for sustained operation near limits.
Does LM2574M-3.3 require an external feedback resistor network?
No, the LM2574M-3.3 does not require external feedback resistors. As a fixed-output variant, its feedback node is internally connected to the 3.3V output pin. Pin 12 (FEEDBACK) is not user-accessible for adjustment and must remain unconnected. This eliminates resistor tolerance errors and temperature drift, ensuring ±4% output accuracy across −40°C to +125°C without calibration.
Can LM2574M-3.3 be used in discontinuous conduction mode (DCM)?
Yes, the LM2574M-3.3 operates reliably in both continuous and discontinuous conduction modes depending on load and inductor value. At light loads (<~50 mA with a 330 µH inductor), the inductor current naturally drops to zero, entering DCM - a normal, documented behavior that maintains regulation and does not affect stability. TI's application notes confirm DCM operation is supported without additional compensation.
What is the thermal pad connection requirement for LM2574M-3.3?
Pin 14 of the LM2574M-3.3 is a thermal pad with no electrical function - it must be soldered directly to a large, low-thermal-resistance copper area on the PCB. TI specifies 4 in² of 1 oz. copper reduces θJA to 78°C/W. Failure to connect this pad significantly degrades thermal performance and may trigger premature thermal shutdown at ≤0.3A load in still-air conditions.
Is LM2574M-3.3 RoHS compliant and lead-free?
Yes, LM2574M-3.3 is RoHS compliant and lead-free per TI's current product change notices. The M-suffix package (M14B) uses matte-tin lead finish and meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL-3). TI provides full compliance documentation including material declarations and test reports on ti.com/product/LM2574M-3.3 under "Quality & Reliability".
LM2574M-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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:
- 500mA
- Frequency - Switching:
- 52kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
LM2574M-3.3 FAQ
1.How can I place an order for LM2574M-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574M-3.3 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 LM2574M-3.3 reliable?
The price and inventory of LM2574M-3.3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2574M-3.3 is usually 5 days.
3.What payment methods are accepted for LM2574M-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574M-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574M-3.3?
LM2574M-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574M-3.3 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 LM2574M-3.3?
For technical support, including LM2574M-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574M-3.3 requirements.
6.How does Aetrix verify that LM2574M-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2574M-3.3 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 LM2574M-3.3 meets industry standards.
7.What is the process for return or replacement of LM2574M-3.3?
All LM2574M-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2574M-3.3, 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 LM2574M-3.3 part is unused and in its original packaging.
Return procedure for LM2574M-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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