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Texas Instruments LM2574M-3.3/NOPB
- Part No.:
- LM2574M-3.3/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LM2574M-3.3/NOPB.pdf
- Description:
- IC REG BUCK 3.3V 500MA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,960
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Product details
Overview
LM2574M-3.3/NOPB from Texas Instruments (formerly National Semiconductor) is a monolithic 0.5A step-down (buck) switching voltage regulator in a 14-pin wide SOIC package, delivering a fixed 3.3V output with ±4% tolerance over line and load, 52 kHz fixed-frequency operation, and integrated thermal shutdown and cycle-by-cycle current limiting. It replaces linear regulators in embedded power supplies requiring high efficiency and minimal external components.
For engineers reviewing the LM2574M-3.3/NOPB datasheet, LM2574M-3.3/NOPB pinout, LM2574M-3.3/NOPB application, or LM2574M-3.3/NOPB equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternatives, and supply-chain support for industrial and embedded power designs.
Technical Context
The LM2574M-3.3/NOPB integrates a PWM controller, power switch, oscillator, error amplifier, and protection circuitry into a single IC. Its internal 52 kHz oscillator drives a N-channel DMOS transistor with 0.9 V typical saturation voltage at 0.5 A, enabling continuous-mode buck conversion without external timing components.
It operates across 4.75–40 V input range, regulates 3.3 V ±4% under 0.1–0.5 A load and −40°C to +125°C junction temperature, and features TTL-compatible ON/OFF control with 50 µA standby current. Feedback is internally connected to set the fixed output; no external resistors are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3 V ±4% over full operating range - ensures stable logic rail for 3.3V microcontrollers without trimming. |
| Max Output Current | 0.5 A continuous - supports moderate-power digital subsystems (e.g., MCU + peripherals) without external boost stages. |
| Input Voltage Range | 4.75 V to 40 V - accommodates unregulated 5V, 12V, or 24V rails common in industrial and automotive auxiliary supplies. |
| Switching Frequency | 52 kHz fixed - enables use of low-cost, high-saturation-current off-the-shelf inductors (e.g., Pulse PE-52627, Renco RL-1284-330). |
| Efficiency | 72% at 12 VIN, 0.5 A - reduces thermal load vs. linear regulators; PCB copper traces suffice as heatsink. |
| Protection Features | Cycle-by-cycle current limit + thermal shutdown - prevents damage during short-circuit or overload without external sensing. |
| Standby Current | 50 µA typical at OFF pin = 5 V - enables low-power sleep modes in battery-backed or energy-conscious systems. |
Pinout & Package
LM2574M-3.3/NOPB uses a 14-pin wide SOIC (NS package code M14B), with exposed thermal pad for enhanced heat dissipation. θJA = 78°C/W with 4 in² copper pour - critical for sustained 0.5A operation at elevated ambient temperatures.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Accepts 4.75–40 V DC; requires ≥22 µF aluminum electrolytic bypass capacitor placed adjacent to pin. |
| 2 (GND) | Power Ground | Primary return path for switch current and control circuitry; must connect directly to thermal pad and main ground plane. |
| 3 (OUT) | Switch Node | Drives external catch diode and inductor; high dv/dt node - layout minimizes loop area to reduce EMI. |
| 4 (GND) | Power Ground | Second ground pin for improved current return path; tied to Pin 2 and thermal pad on PCB. |
| 5 (ON/OFF) | Enable Control Input | TTL-compatible shutdown: ≤0.8 V = ON, ≥2.2 V = OFF; draws only 12 µA when active, 50 µA in standby. |
| 6 (GND) | Power Ground | Third ground pin supporting low-impedance return for feedback and bias networks. |
| 7 (FEEDBACK) | Internal Fixed Reference | No connection required - internally tied to output divider; unused pin in fixed-output variants. |
| 8 (GND) | Power Ground | Fourth ground pin; all GND pins and thermal pad must be solidly interconnected. |
| 9–14 (NC / Thermal Pad) | No Connect / Thermal Interface | Pins 9–13 are NC; Pin 14 is thermal pad - must be soldered to ≥4 in² copper area for thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external resistor network - reduces BOM count, layout sensitivity, and drift-related regulation error. |
| 0.5A integrated switch | Supports full-load operation without external MOSFET - simplifies design and improves reliability vs. discrete solutions. |
| 52 kHz fixed oscillator | Enables predictable EMI filtering and compatibility with standard inductor families - avoids frequency variation due to temp/aging. |
| TTL shutdown | Allows system-level power sequencing and low-power sleep states using standard logic-level signals. |
| Thermal + current protection | Self-protecting under fault conditions - removes need for external current sense or thermal cutoff circuits. |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
|
Use Scenario: Powers 3.3V microcontroller, CAN transceiver, and analog sensor interface from a 12V vehicle battery with load dumps up to 40V. IC Role / Device Role / Timing Role: Primary DC-DC buck regulator providing clean, regulated 3.3V rail with transient immunity and thermal resilience. Use Value: Withstands 40V input surges, delivers 0.5A continuously, and shuts down safely during overtemperature events - meets ISO 7637-2 pulse requirements. |
Use Scenario: Supplies 3.3V logic rail for door module MCU and LIN transceiver in harsh under-hood environments. IC Role / Device Role / Timing Role: High-efficiency step-down regulator replacing linear LDOs to minimize heat buildup in sealed enclosures. Use Value: 72% efficiency at 12V→3.3V/0.5A reduces thermal stress; −40°C to +125°C rating ensures operation across full automotive temperature range. |
| Medical Patient Monitor Subsystem | Industrial Ethernet Gateway |
|
Use Scenario: Generates isolated 3.3V supply for ADC front-end and low-noise signal conditioning circuitry. IC Role / Device Role / Timing Role: Pre-regulator feeding low-noise LDOs - reduces dropout and thermal load on downstream linear regulators. Use Value: Fixed 3.3V ±4% accuracy ensures consistent reference stability; 52 kHz switching allows effective LC filtering before sensitive analog stages. |
Use Scenario: Powers 3.3V PHY, Ethernet MAC, and flash memory in DIN-rail mounted gateway with 24V DC input. IC Role / Device Role / Timing Role: Main system power converter handling variable loads from idle to full packet throughput. Use Value: 0.5A output supports burst-mode Ethernet traffic; ON/OFF pin enables remote power cycling via microcontroller GPIO. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2574N-3.3 | 8-pin DIP package (θJA = 72°C/W with 4 in² copper); same electrical specs but lower power density and manual assembly compatible. | Suitable for prototyping, low-volume through-hole boards, or legacy designs where SOIC reflow is unavailable. | Select when board assembly process mandates through-hole, or when thermal margin exceeds 78°C/W requirement of M-package. |
| LM2596-3.3 | 3A output capability, 150 kHz switching, wider VIN (4.5–40V), adjustable version available; not pin-compatible. | Required for higher-current applications (>0.5A) or where smaller inductors are preferred due to higher frequency. | Choose when load exceeds 0.5A or when board space constraints favor smaller magnetics - redesign required. |
Compared with LM2574N-3.3, the LM2574M-3.3/NOPB offers superior thermal performance in surface-mount layouts; compared with LM2596-3.3, it trades current capacity and frequency for proven robustness, lower EMI, and simpler external component selection in 0.5A-class designs.
Availability
LM2574M-3.3/NOPB is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and medical monitoring systems requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for LM2574M-3.3/NOPB 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 LM2574 series was designed specifically for cost-sensitive, medium-power DC-DC conversion in industrial and embedded systems where reliability, simplicity, and thermal efficiency outweigh ultra-high current or ultra-small footprint requirements.
FAQ
What is the maximum input voltage rating for LM2574M-3.3/NOPB?
The absolute maximum input voltage for LM2574M-3.3/NOPB is 45 V, with recommended operating range up to 40 V. Exceeding 40 V risks violating the guaranteed output regulation spec (±4%) and may trigger internal protection. The HV variant (LM2574HV) supports up to 60 V operating input, but LM2574M-3.3/NOPB is the standard-voltage version. Always observe derating guidelines per TI datasheet DS011394.
Does LM2574M-3.3/NOPB require external feedback resistors?
No, LM2574M-3.3/NOPB does not require external feedback resistors. It is a fixed-output variant with internal resistor divider setting the 3.3 V output; the FEEDBACK pin (Pin 7) is internally connected and must remain unconnected in PCB layout. This eliminates resistor tolerance errors and thermal drift effects seen in adjustable versions like LM2574M-ADJ.
Can LM2574M-3.3/NOPB be used in discontinuous conduction mode (DCM)?
Yes, LM2574M-3.3/NOPB operates reliably in both continuous and discontinuous conduction modes. At light loads (<~100 mA), inductor current naturally drops to zero, entering DCM - a normal, documented behavior. Efficiency remains acceptable, and no design changes are needed; the IC's current limit and oscillator behavior adapt inherently per datasheet Figure 10 and Section "Inductor Ripple Current".
What is the thermal pad connection requirement for LM2574M-3.3/NOPB?
The thermal pad (Pin 14) of LM2574M-3.3/NOPB must be soldered to a minimum 4 in² copper area on the PCB to achieve the specified θJA = 78°C/W. Using less copper raises junction temperature significantly - e.g., 1 in² increases θJA to 102°C/W. Vias to inner-layer planes are recommended, and the pad must be electrically connected to GND (Pins 2, 4, 6, 8) for both thermal and electrical integrity.
Is LM2574M-3.3/NOPB RoHS compliant and lead-free?
Yes, LM2574M-3.3/NOPB is RoHS compliant and lead-free. The "/NOPB" suffix explicitly denotes lead-free packaging per TI's product nomenclature. It meets JEDEC J-STD-020 moisture sensitivity level (MSL) 3 and is qualified for Pb-free reflow soldering profiles. Full compliance documentation is available in TI's official product folder for LM2574M-3.3/NOPB.
LM2574M-3.3/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-SOIC (0.295", 7.50mm Width)
- 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:
- 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/NOPB FAQ
1.How can I place an order for LM2574M-3.3/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574M-3.3/NOPB 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/NOPB reliable?
The price and inventory of LM2574M-3.3/NOPB 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/NOPB is usually 5 days.
3.What payment methods are accepted for LM2574M-3.3/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574M-3.3/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574M-3.3/NOPB?
LM2574M-3.3/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574M-3.3/NOPB 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/NOPB?
For technical support, including LM2574M-3.3/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574M-3.3/NOPB requirements.
6.How does Aetrix verify that LM2574M-3.3/NOPB is sourced from the original manufacturer or authorized distributors?
All LM2574M-3.3/NOPB 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/NOPB meets industry standards.
7.What is the process for return or replacement of LM2574M-3.3/NOPB?
All LM2574M-3.3/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM2574M-3.3/NOPB, 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/NOPB part is unused and in its original packaging.
Return procedure for LM2574M-3.3/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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