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Texas Instruments LM2574MX-3.3
- Part No.:
- LM2574MX-3.3
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LM2574MX-3.3.pdf
- Description:
- IC REG BUCK 3.3V 500MA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,683
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Product details
Overview
LM2574MX-3.3 from Texas Instruments (formerly National Semiconductor) is a monolithic 0.5A step-down (buck) switching voltage regulator with fixed 3.3V output, 52 kHz internal oscillator, and integrated switch. It delivers ±4% output voltage accuracy across −40°C to +125°C, supports 4.75–40V input, and requires only four external components for operation - used in embedded power rails, industrial controllers, and point-of-load DC/DC conversion.
For engineers reviewing the LM2574MX-3.3 datasheet, LM2574MX-3.3 pinout, LM2574MX-3.3 application, or LM2574MX-3.3 equivalent, key selection criteria include guaranteed 0.5A output current, thermal shutdown protection, TTL-compatible shutdown control, and compatibility with standard off-the-shelf inductors (e.g., 330 µH).
Technical Context
The LM2574MX-3.3 implements a fixed-frequency, current-mode buck topology with internal 52 kHz oscillator and cycle-by-cycle current limiting. Its integrated NPN switch features 0.9 V typical saturation voltage at 0.5A, enabling high-efficiency conversion without external gate drivers.
It operates in continuous conduction mode under typical loads (≥100 mA), supports adjustable soft-start via input capacitor sizing, and uses feedback regulation referenced to an internal 1.23V bandgap - though this reference is not exposed externally in fixed-output versions like LM2574MX-3.3.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±4% over full temperature and load range (0.1–0.5A, −40°C to +125°C) |
| Max Output Current | 0.5A DC - sufficient for powering microcontrollers, FPGAs, and logic I/O rails |
| Input Voltage Range | 4.75V to 40V - compatible with 5V, 12V, and 24V industrial bus inputs |
| Switching Frequency | 52 kHz fixed - enables use of low-cost, high-saturation-current inductors (e.g., Pulse PE-52627) |
| Efficiency | 72% at VIN = 12V, IOUT = 0.5A - reduces thermal load vs. linear regulators |
| Shutdown Current | 50 µA typical - enables low-power standby in battery-backed systems |
| Thermal Protection | Internal thermal shutdown - prevents damage during overload or poor PCB heatsinking |
Pinout & Package
LM2574MX-3.3 is supplied in a 14-lead wide-body surface-mount (WM) package (NS package code M14B), with exposed pad for thermal enhancement. Pin 1 is marked by dot; pins are arranged in two rows (7 per side). The package requires minimum 4 in² copper pour for θJA = 78°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Supply | Primary DC input (4.75–40V); bypass with ≥22 µF electrolytic capacitor |
| 2 (GND) | Power Ground | Common return for input/output capacitors and inductor; connect to thermal pad |
| 3 (OUT) | Switch Node | Drives external catch diode and inductor; carries pulsed 0.5A current |
| 4 (GND) | Power Ground | Second ground connection - must be tied to same plane as Pin 2 |
| 5 (FEEDBACK) | Not connected | No internal connection; leave unconnected or float (not used in fixed-output version) |
| 6 (ON/OFF) | Shutdown Control | TTL-compatible enable: <1.0V = ON, >2.2V = OFF; draws ≤30 µA in shutdown |
| 7 (GND) | Power Ground | Third ground pin - ties to thermal pad and system ground plane |
| 8–14 (NC) | No Connection | Internally unused; may be left open or grounded for mechanical stability |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external resistor divider; ensures stable core voltage for 3.3V logic without calibration |
| Integrated switch with current limit | Enables self-protecting operation up to 1.6A peak; no external MOSFET or sense resistor required |
| 52 kHz fixed-frequency oscillator | Reduces EMI filtering complexity and allows use of low-cost, high-current inductors (e.g., Renco RL-1284-330) |
| TTL shutdown interface | Supports microcontroller-controlled power sequencing with <10 µA leakage in OFF state |
| Thermal shutdown + cycle-by-cycle current limit | Provides fault recovery without latch-up - resumes normal operation after cooling or load removal |
Applications
| Industrial PLC I/O Power | Embedded Microcontroller Core Rail |
|---|---|
|
Use Scenario: Powering digital I/O modules in programmable logic controllers with 24V backplane input. IC Role / Device Role / Timing Role: Primary step-down regulator converting 24V to isolated 3.3V for FPGA configuration and sensor interface logic. Use Value: Delivers 0.5A at 72% efficiency with no heatsink needed - simplifies enclosure thermal design and meets EN 61000-6-4 emission limits. |
Use Scenario: Generating stable 3.3V supply for ARM Cortex-M4 microcontrollers in edge-node sensor gateways. IC Role / Device Role / Timing Role: On-board DC/DC converter replacing linear regulator to reduce board temperature rise in sealed enclosures. Use Value: Maintains ±4% output accuracy across −40°C to +85°C ambient - ensures reliable boot and ADC reference stability. |
| POS Terminal Mainboard Power | Test Equipment Auxiliary Rail |
|
Use Scenario: Providing regulated 3.3V to payment processing SoCs and display controllers in retail point-of-sale terminals. IC Role / Device Role / Timing Role: Secondary buck stage following AC/DC adapter; handles transient loads from touchscreen and printer actuation. Use Value: Withstands 500 mA load steps with <50 mV overshoot (COUT = 220 µF) - prevents brownout resets during concurrent peripheral activation. |
Use Scenario: Generating clean 3.3V for analog front-end circuitry in portable multimeters and signal analyzers. IC Role / Device Role / Timing Role: Low-noise power source for precision op-amps and 16-bit ADCs, operating from 9V battery or bench supply. Use Value: Achieves <15 mVPP output ripple with proper LC filter - avoids aliasing in sub-100 kHz measurement bandwidths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2576-3.3 | 0.3A lower quiescent current (5 mA vs. 10 mA max), higher peak current limit (3A vs. 1.6A), same 52 kHz frequency | Preferred where light-load efficiency matters more than peak surge capability | Select LM2576-3.3 if system spends >70% time at <50 mA load; verify inductor saturation rating for 3A peak |
| TPS54302DDCR | Higher switching frequency (2.2 MHz), smaller external components, but requires external compensation and has 0.6V reference | Better suited for space-constrained designs needing fast transient response | Choose TPS54302DDCR only when PCB area is critical and design team has SMPS layout expertise; LM2574MX-3.3 offers simpler BOM and proven reliability |
Compared with LM2576-3.3 and TPS54302DDCR, LM2574MX-3.3 provides the most straightforward drop-in replacement for legacy linear regulator upgrades, requiring minimal layout changes and no loop compensation tuning - ideal for cost-sensitive industrial designs with moderate performance requirements.
Availability
LM2574MX-3.3 is available at Aetrix Electronics and suitable for industrial automation, test equipment, and embedded computing applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LM2574MX-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 support and manufacturing continuity for the SIMPLE SWITCHER™ product line.
The LM2574MX-3.3 belongs to TI's SIMPLE SWITCHER™ family of easy-to-use DC/DC converters, designed specifically for engineers transitioning from linear regulators to switching solutions without complex design overhead.
FAQ
What is the maximum input voltage rating for LM2574MX-3.3?
The absolute maximum input voltage for LM2574MX-3.3 is 45V, but the recommended operating maximum is 40V. Exceeding 40V risks violating the guaranteed output voltage tolerance and may trigger thermal shutdown under sustained load. Always observe derating curves in the official datasheet DS011394 for extended temperature operation.
Can LM2574MX-3.3 be used with an input voltage as low as 4.75V?
Yes, LM2574MX-3.3 is specified to regulate correctly down to 4.75V input while delivering full 0.5A output at 3.3V. At this minimum input, duty cycle approaches 98%, so ensure the external catch diode (e.g., SR102) has low forward voltage and the inductor has low DCR to maintain efficiency above 65%.
Does LM2574MX-3.3 require an external feedback resistor network?
No, LM2574MX-3.3 is a fixed-output variant - the feedback node (Pin 5) is internally connected to the 3.3V regulation circuit and must be left unconnected. Unlike the adjustable LM2574-ADJ, it contains no external resistor divider and does not support output voltage modification.
What is the thermal resistance (θJA) of LM2574MX-3.3 in its standard package?
LM2574MX-3.3 in the M14B wide-body surface-mount package has θJA = 102°C/W with 1 in² copper and 78°C/W with 4 in² copper (1 oz. thickness). These values assume direct thermal connection of the exposed pad to the PCB ground plane - omitting this connection increases junction temperature by >25°C at full load.
How does the ON/OFF pin function on LM2574MX-3.3?
The ON/OFF pin (Pin 6) provides TTL-compatible enable control: driving it below 1.0V (typical) enables regulation; pulling it above 2.2V disables the internal switch and reduces quiescent current to 50 µA. No pull-up or pull-down resistors are required - the pin has built-in hysteresis and leakage <12 µA.
LM2574MX-3.3 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 14-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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
LM2574MX-3.3 FAQ
1.How can I place an order for LM2574MX-3.3 through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574MX-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 LM2574MX-3.3 reliable?
The price and inventory of LM2574MX-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 LM2574MX-3.3 is usually 5 days.
3.What payment methods are accepted for LM2574MX-3.3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574MX-3.3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574MX-3.3?
LM2574MX-3.3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574MX-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 LM2574MX-3.3?
For technical support, including LM2574MX-3.3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574MX-3.3 requirements.
6.How does Aetrix verify that LM2574MX-3.3 is sourced from the original manufacturer or authorized distributors?
All LM2574MX-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 LM2574MX-3.3 meets industry standards.
7.What is the process for return or replacement of LM2574MX-3.3?
All LM2574MX-3.3 units undergo pre-shipment inspection (PSI). If there is an issue with LM2574MX-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 LM2574MX-3.3 part is unused and in its original packaging.
Return procedure for LM2574MX-3.3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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