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Texas Instruments LM2574MX-ADJ
- Part No.:
- LM2574MX-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LM2574MX-ADJ.pdf
- Description:
- IC REG BUCK ADJ 500MA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,575
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Product details
Overview
LM2574MX-ADJ from Texas Instruments (formerly National Semiconductor) is a monolithic 0.5A step-down (buck) switching voltage regulator with adjustable output, internal 52 kHz oscillator, cycle-by-cycle current limiting, thermal shutdown, and TTL-compatible shutdown control. It delivers ±4% output voltage accuracy over line/load/temperature and supports 1.23V–37V output range using two external resistors. It replaces linear regulators in medium-power DC-DC conversion applications such as industrial power supplies and embedded system rails.
For engineers reviewing the LM2574MX-ADJ datasheet, LM2574MX-ADJ pinout, LM2574MX-ADJ application, or LM2574MX-ADJ equivalent, key selection considerations include its fixed 52 kHz switching frequency, 40V max input (non-HV version), 0.5A guaranteed output current, feedback reference voltage of 1.23 V, and requirement for only four external components - making it suitable for cost-sensitive, thermally constrained buck designs where efficiency >77% at 5V/0.5A is critical.
Technical Context
The LM2574MX-ADJ integrates a PWM controller, power switch, oscillator, error amplifier, and protection circuitry into a single SOIC-8 package. Its architecture uses voltage-mode control with internal frequency compensation and a fixed 52 kHz oscillator - eliminating need for external timing components. The feedback loop references the 1.23 V internal bandgap at the FB pin to regulate output via external resistor divider.
Protection features include cycle-by-cycle peak current limiting (1.0 A typical limit), thermal shutdown at ~150°C junction temperature, and low-quiescent standby mode (50 µA typical) activated by the ON/OFF pin. Input voltage range is 4V to 40V, and dropout behavior is defined by minimum on-time and saturation voltage (0.9 V typical at 0.5A).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 0.5 A guaranteed - sufficient for powering microcontrollers, sensors, and logic rails without external pass devices. |
| Input Voltage Range | 4 V to 40 V - supports wide-range unregulated inputs including 12 V, 24 V, and 36 V industrial bus systems. |
| Feedback Reference Voltage | 1.23 V ±1.3% - sets output voltage precision when used with external R1/R2 divider; enables 1.23 V–37 V programmable range. |
| Switching Frequency | 52 kHz fixed - simplifies EMI filtering design and allows use of low-cost, high-saturation-current off-the-shelf inductors. |
| Efficiency | 77% at VIN = 12 V, VOUT = 5 V, IOUT = 0.5 A - reduces thermal load vs. linear regulators; PCB copper traces suffice as heatsink. |
| Quiescent Current | 5 mA typical operating / 50 µA standby - enables low-power sleep modes in battery-backed or energy-conscious systems. |
| Thermal Resistance (θJA) | 78 °C/W (SOIC-8, 4 in² copper) - defines junction-to-ambient rise under full load; requires minimal PCB copper area for thermal management. |
Pinout & Package
LM2574MX-ADJ is housed in an 8-pin SOIC (Small Outline Integrated Circuit) package (TI package code D), with exposed pad not electrically connected but recommended for thermal enhancement via soldering to PCB copper.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VIN) | Input Power Supply | Accepts 4–40 V DC; requires ≥22 µF input capacitor placed close to pin for stability and ripple suppression. |
| 2 (GND) | Power Ground | Common return for input, output, and internal circuitry; must be low-inductance connection to minimize noise and switching transients. |
| 3 (OUT) | Switch Node | Drives external catch diode and inductor; carries pulsed 0.5 A current; layout critical to minimize EMI and voltage spikes. |
| 4 (FB) | Feedback Input | High-impedance (50 nA bias) node sensing output via resistor divider; sensitive to noise - route away from switching nodes. |
| 5 (ON/OFF) | Shutdown Control | TTL-compatible enable pin: <1.0 V disables (50 µA standby), >2.2 V enables; open-circuit defaults to ON. |
| 6 (GND) | Signal Ground | Dedicated ground for feedback and control circuitry; tied to Pin 2 externally per layout guidelines. |
| 7 (GND) | Power Ground (redundant) | Second GND pin for improved thermal and current handling; must be connected to same ground plane as Pins 2 and 6. |
| 8 (NC) | No Connection | Not internally bonded; left unconnected or grounded per PCB thermal requirements (no electrical function). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 0.5A power switch | Eliminates need for external MOSFET or transistor; reduces BOM count and layout complexity in buck topology. |
| Fixed 52 kHz oscillator | Enables predictable EMI profile and compatibility with standard inductor families optimized for this frequency. |
| ±4% output voltage tolerance | Guaranteed over full line, load, and temperature range - ensures stable rail generation without post-regulation. |
| Cycle-by-cycle current limiting | Protects against short-circuit and overload faults without latch-up; maintains regulation during transient overloads. |
| TTL-compatible shutdown | Allows microcontroller-driven power sequencing and low-power sleep states with sub-100 µA system standby current. |
Applications
| Industrial Power Supply | Embedded System Rail Generator |
|---|---|
|
Use Scenario: Converting 24 V factory bus to 5 V or 3.3 V for PLC I/O modules and sensor interfaces. IC Role / Device Role / Timing Role: Primary step-down regulator providing isolated, efficient, and thermally manageable DC-DC conversion. Use Value: Replaces linear regulators to eliminate heat sinks, reduce board space, and achieve >77% efficiency at 0.5 A load. |
Use Scenario: Generating clean 3.3 V supply for ARM Cortex-M microcontrollers and peripheral ICs in edge devices. IC Role / Device Role / Timing Role: Adjustable-output buck converter configured for precise 3.3 V with tight tolerance and low ripple. Use Value: Delivers ±4% output accuracy across temperature and load while supporting simple resistor-based programming. |
| On-Card Buck Converter | Positive-to-Negative Inverter (Buck-Boost) |
|
Use Scenario: Local voltage regulation on dense PCBs where space and thermal dissipation are constrained. IC Role / Device Role / Timing Role: Compact SOIC-8 DC-DC solution requiring only four external passive components. Use Value: Minimizes component footprint and simplifies layout with integrated switch and fixed-frequency operation. |
Use Scenario: Generating −5 V or −12 V from a positive input for op-amp biasing or analog signal conditioning. IC Role / Device Role / Timing Role: Configured in inverting buck-boost topology using external diode and inductor. Use Value: Leverages same control architecture and protection features for bipolar rail generation without additional ICs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2575MX-ADJ | Higher 1 A output current, 52 kHz frequency, wider 4–40 V input, but larger SOIC-16 package and higher quiescent current (10 mA). | Better suited for higher-load applications (>0.5 A); less ideal for space-constrained layouts due to larger footprint. | Select LM2575MX-ADJ if load exceeds 0.5 A or if higher current headroom is required; otherwise LM2574MX-ADJ offers better size/cost trade-off. |
| MP1584EN-LF-Z | 4.5–28 V input, 3 A output, 1.5 MHz switching, smaller SOIC-8 package, but requires external compensation and lacks integrated soft-start. | Enables smaller magnetics and lower output capacitance; not drop-in compatible due to different pinout and control architecture. | Choose MP1584EN-LF-Z for higher efficiency at light loads or compact high-frequency designs; LM2574MX-ADJ remains preferred for simplicity and legacy compatibility. |
Compared with LM2575MX-ADJ and MP1584EN-LF-Z, the LM2574MX-ADJ provides optimal balance of integration, thermal performance, and design simplicity for ≤0.5 A buck applications - especially where fixed-frequency predictability, minimal external parts, and proven reliability in industrial environments are prioritized.
Availability
LM2574MX-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, embedded system rail generation, on-card DC-DC conversion, and positive-to-negative inverter circuits requiring stable component supply, long-lifecycle support, and consistent parametric performance.
Supply support for LM2574MX-ADJ 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 LM2574MX-ADJ belongs to TI's SIMPLE SWITCHER™ family of integrated buck regulators, designed specifically for ease-of-use, minimal external component count, and robust operation in industrial, automotive, and communications power systems.
FAQ
What is the maximum input voltage rating for LM2574MX-ADJ?
The LM2574MX-ADJ has an absolute maximum input voltage of 45 V and an operating maximum input voltage of 40 V. Exceeding 40 V during normal operation risks violating the device's safe operating area and may trigger thermal shutdown or reduce long-term reliability. For applications requiring >40 V input, the LM2574HV-ADJ variant (60 V operating / 63 V absolute max) should be used instead of LM2574MX-ADJ.
How do I calculate the output voltage for LM2574MX-ADJ?
The output voltage of LM2574MX-ADJ is set using two external resistors (R1 and R2) connected between VOUT, FB, and GND. The formula is VOUT = 1.23 V × (1 + R2/R1), where R1 connects FB to GND and R2 connects VOUT to FB. For best accuracy and temperature stability, use 1% metal-film resistors with R1 between 1 kΩ and 5 kΩ - e.g., R1 = 1.0 kΩ and R2 = 18.7 kΩ yields VOUT ≈ 24.2 V. This calculation applies directly to LM2574MX-ADJ in standard buck configuration.
Does LM2574MX-ADJ require an external diode, and what type is recommended?
Yes, LM2574MX-ADJ requires an external Schottky catch diode connected from the OUT pin to GND. Recommended diodes include MBR150 (50 V, 1 A), 11DQ05 (50 V, 1 A), or SR105 (50 V, 1 A), all selected for low forward voltage (<0.55 V) and fast recovery to minimize conduction loss and switching stress. The diode's reverse voltage rating must exceed 1.25× the maximum input voltage, and its current rating should be ≥1.5× the maximum load current - critical for reliable operation of LM2574MX-ADJ under transient or short-circuit conditions.
What is the purpose of the ON/OFF pin on LM2574MX-ADJ?
The ON/OFF pin on LM2574MX-ADJ enables external control of regulator operation: pulling the pin below 1.0 V (typical) disables the IC and reduces quiescent current to 50 µA (typical), while pulling it above 2.2 V (typical) enables normal regulation. This feature supports power sequencing, battery-saving sleep modes, and system-level fault response. When left unconnected, the internal pull-up keeps LM2574MX-ADJ enabled - no external pull-up resistor is needed unless noise immunity is required in high-noise environments.
Can LM2574MX-ADJ be used in discontinuous conduction mode (DCM)?
Yes, LM2574MX-ADJ operates reliably in both continuous and discontinuous conduction modes depending on load, input voltage, and inductor value. At light loads (<~100 mA), the inductor current naturally falls to zero each cycle - entering DCM - which is fully supported and does not affect regulation or protection functionality. DCM reduces switching losses and improves light-load efficiency, though output ripple increases slightly. Designers may intentionally select smaller inductors (e.g., 68 µH or 100 µH) to operate LM2574MX-ADJ in DCM for specific efficiency or size targets.
LM2574MX-ADJ 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:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.23V
- Voltage - Output (Max):
- 37V
- 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-ADJ FAQ
1.How can I place an order for LM2574MX-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574MX-ADJ 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-ADJ reliable?
The price and inventory of LM2574MX-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2574MX-ADJ is usually 5 days.
3.What payment methods are accepted for LM2574MX-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574MX-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574MX-ADJ?
LM2574MX-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574MX-ADJ 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-ADJ?
For technical support, including LM2574MX-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574MX-ADJ requirements.
6.How does Aetrix verify that LM2574MX-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2574MX-ADJ 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-ADJ meets industry standards.
7.What is the process for return or replacement of LM2574MX-ADJ?
All LM2574MX-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2574MX-ADJ, 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-ADJ part is unused and in its original packaging.
Return procedure for LM2574MX-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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