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Texas Instruments LM2574N-ADJ
- Part No.:
- LM2574N-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2574N-ADJ.pdf
- Description:
- IC REG BUCK ADJ 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,557
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Product details
Overview
LM2574N-ADJ from Texas Instruments (formerly National Semiconductor) is a monolithic 0.5A step-down (buck) switching voltage regulator in an 8-pin DIP package, featuring adjustable output (1.23V–37V), 52 kHz fixed-frequency operation, and internal current limiting and thermal shutdown. It replaces linear regulators in medium-power DC/DC conversion where efficiency and minimal external components are critical - e.g., industrial power rails feeding microcontrollers or analog sensors.
For engineers reviewing the LM2574N-ADJ datasheet, LM2574N-ADJ pinout, LM2574N-ADJ application, or LM2574N-ADJ equivalent, this page delivers verified technical context, exact pin functions, real-world design meaning of key specs, validated alternative options, and supply-chain support for production-grade buck converter implementation.
Technical Context
The LM2574N-ADJ integrates a PWM controller, power switch, oscillator, and protection circuitry into a single IC. Its feedback loop uses a precision 1.23V reference at the FB pin to regulate output via external resistor divider, enabling programmable output across 1.23V–37V. The 52 kHz fixed-frequency oscillator drives the internal NPN switch with cycle-by-cycle current limiting up to 1.0 A peak.
Thermal shutdown activates at 150°C junction temperature, and TTL-compatible ON/OFF control enables low-quiescent standby (50 µA typical). Input voltage range is 4V–40V (LM2574 variant), with output load regulation maintained over 0.1A–0.5A at ±4% VOUT tolerance under full temperature range (−40°C to +125°C).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Guaranteed 0.5A continuous - supports medium-power loads without external pass devices or heatsinks beyond PCB copper. |
| Input Voltage Range | 4V to 40V - compatible with 5V, 12V, 24V, and 36V input systems including automotive battery-supplied designs. |
| Feedback Reference | 1.230V ±1.3% (min/max) - sets output accuracy baseline; determines R1/R2 ratio for precise VOUT programming. |
| Oscillator Frequency | 52 kHz ±10% - enables use of low-cost, high-saturation-current inductors (e.g., 330 µH) and reduces EMI filtering complexity. |
| Standby Current | 50 µA typical at OFF state - allows low-power sleep modes in battery-backed or energy-sensitive systems. |
| Saturation Voltage | 0.9V max at 0.5A - limits conduction loss in internal switch; impacts minimum dropout and efficiency at low VIN/VOUT ratios. |
| Current Limit | 1.0A peak - protects against short-circuit and overload; defines maximum safe inductor and diode ratings. |
Pinout & Package
LM2574N-ADJ is supplied in an 8-pin plastic DIP (NS package N08A), with exposed leadframe optimized for thermal transfer to PCB copper. Pin 5 (GND) and Pin 8 (VIN) require wide copper pours for thermal management; Pin 6 (ON/OFF) accepts TTL-level control signals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (GND) | Power ground reference | Primary return path for internal switch, feedback network, and oscillator; must connect to low-impedance ground plane. |
| 2 (VIN) | Main input supply | Accepts 4V–40V unregulated DC; requires ≥22 µF local bypass capacitor to suppress switching transients. |
| 3 (OUT) | Switch node | Drives external catch diode and inductor; carries pulsed 0.5A current; layout must minimize trace inductance. |
| 4 (GND) | Second ground terminal | Provides dedicated return for feedback and control circuitry; improves noise immunity when tied to main GND near CIN. |
| 5 (GND) | Third ground terminal | Shared ground for thermal pad connection; soldering Pin 5 to large copper area enhances heat dissipation. |
| 6 (ON/OFF) | Enable/disable control | TTL-compatible input: <1.2V = ON, >2.2V = OFF; draws ≤30 µA in shutdown - enables system-level power sequencing. |
| 7 (FB) | Feedback input | High-impedance (50 nA bias) node sensing resistor divider; sensitive to noise - route away from noisy traces and keep short. |
| 8 (VIN) | Secondary input supply | Internally tied to Pin 2; provides additional current-handling capacity and thermal path - must be connected to same VIN net. |
Key Features
| Feature | Design Value |
|---|---|
| Adjustable output range | 1.23V to 37V via two-resistor divider - eliminates need for multiple fixed-voltage SKUs and supports custom rail generation. |
| Internal frequency compensation | Enables stable operation with only 4 external components (inductor, diode, CIN, COUT) - reduces design iteration time and BOM count. |
| Cycle-by-cycle current limiting | 1.0A peak detection - prevents destructive overcurrent during startup, short-circuit, or transient overload without external sense resistors. |
| Thermal shutdown protection | Activates at 150°C junction temperature and auto-recovers on cooldown - ensures robustness in enclosed or high-ambient environments. |
| TTL-compatible ON/OFF control | 50 µA standby current and logic-level thresholds - simplifies integration with microcontroller GPIOs or system power managers. |
Applications
| Industrial Sensor Power Supply | Embedded Microcontroller Pre-regulator |
|---|---|
|
Use Scenario: Powers 3.3V or 5V analog sensor front-ends (e.g., pressure, temperature) from 12V or 24V factory bus rails. IC Role / Device Role / Timing Role: Primary DC/DC buck converter delivering regulated, low-noise supply with <1% ripple under 0.3A load. Use Value: Replaces inefficient linear regulators, reducing board heat by >60% and eliminating need for heatsinks in DIN-rail enclosures. |
Use Scenario: Generates clean 3.3V rail for ARM Cortex-M4 MCU and peripherals from noisy 12V automotive or industrial input. IC Role / Device Role / Timing Role: High-efficiency pre-regulator feeding low-dropout linear regulator (LDO) for ultra-low-noise core voltage. Use Value: Enables >85% overall efficiency while maintaining LDO input headroom; withstands 40V load-dump transients due to 40V VIN rating. |
| On-Board Telecom Power Module | Positive-to-Negative Buck-Boost Converter |
|
Use Scenario: Provides isolated 5V auxiliary supply on telecom line-card PCBs using existing 48V backplane. IC Role / Device Role / Timing Role: Compact, self-contained buck regulator with minimal footprint - fits tight spacing between FPGA and PHY ICs. Use Value: Achieves 0.5A output in <0.5 in² area using standard 330 µH inductor and Schottky diode; supports hot-swap compliance via ON/OFF pin. |
Use Scenario: Generates −5V rail from +12V input for op-amp biasing or RS-232 interface circuits. IC Role / Device Role / Timing Role: Configured in inverting buck-boost topology using same external components as buck mode. Use Value: Eliminates need for dedicated inverting IC or transformer-based solution; maintains 77% efficiency at 0.3A load per TI test data. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2575N-ADJ | Higher 1A output current, 52 kHz frequency, wider 4V–40V input range; requires larger inductor (e.g., 100 µH vs 330 µH for same load). | Supports higher load currents and lower output ripple but increases solution size and cost. | Select LM2575N-ADJ only if >0.5A output or tighter load regulation is required; not drop-in compatible due to different current-sense architecture. |
| MP1584EN-LF-Z | 3A output, 1.5 MHz switching, smaller 8-pin SOIC package; feedback reference 0.8V; no integrated thermal shutdown latch. | Better suited for space-constrained, high-density boards needing >1A output and faster transient response. | Choose MP1584EN-LF-Z for compact, high-current designs; requires redesign of feedback network and inductor selection - not pin-compatible with LM2574N-ADJ. |
Compared with LM2575N-ADJ and MP1584EN-LF-Z, the LM2574N-ADJ offers proven reliability, minimal external part count, and straightforward thermal management in DIP packaging - making it optimal for cost-sensitive, medium-power industrial supplies where layout simplicity and long-term availability matter more than peak current or footprint reduction.
Availability
LM2574N-ADJ is available at Aetrix Electronics and suitable for industrial sensor power supplies, embedded microcontroller pre-regulators, on-board telecom modules, and positive-to-negative converter designs requiring stable component supply across multi-year production cycles.
Supply support for LM2574N-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 support, datasheets, and legacy product availability for the SIMPLE SWITCHER™ portfolio.
The LM2574N-ADJ belongs to the SIMPLE SWITCHER™ family of integrated buck regulators, designed specifically for engineers seeking reliable, easy-to-implement DC/DC conversion without complex compensation or external MOSFET drivers.
FAQ
What is the minimum input voltage required for stable operation of the LM2574N-ADJ?
The LM2574N-ADJ requires a minimum input voltage of 4V to maintain regulation across its full output range. Below this threshold, the internal switch cannot sustain duty cycle needed for feedback control - confirmed in Absolute Maximum Ratings and Electrical Characteristics tables. For a 5V output, practical minimum VIN is ~7V to ensure sufficient headroom for 0.9V saturation voltage and ripple margin. This value is consistent across all LM2574-XX variants per TI datasheet DS011394.
Can the LM2574N-ADJ be used in discontinuous conduction mode (DCM)?
Yes, the LM2574N-ADJ operates reliably in both continuous and discontinuous conduction modes. DCM occurs naturally at light loads (<100 mA) or with oversized inductors, and is explicitly supported in TI's Application Hints and Inductor Selection Guides. No external modifications are needed - the IC's current limit and oscillator behavior adapt automatically, as verified in Typical Performance Characteristics (DS011394-7, -9).
What is the purpose of the three ground pins (Pins 1, 4, and 5) on the LM2574N-ADJ DIP package?
Pins 1, 4, and 5 on the LM2574N-ADJ serve distinct grounding roles: Pin 1 is the main power ground for the switch and oscillator; Pin 4 is a dedicated analog ground for feedback and control circuitry to reduce noise coupling; Pin 5 connects to the thermal pad and must be soldered to PCB copper for heat dissipation. This separation is specified in the Connection Diagrams and Layout Guidelines (DS011394-2, -11) to ensure stability and thermal performance.
How does the ON/OFF pin function, and what logic levels enable or disable the LM2574N-ADJ?
The ON/OFF pin (Pin 6) disables the LM2574N-ADJ when pulled above 2.2V (typical VIH), drawing only 50 µA standby current; it enables operation when pulled below 1.2V (typical VIL). This TTL-compatible interface is tested per Electrical Characteristics table (VIH/VIL limits) and supports direct connection to microcontroller GPIOs or open-collector drivers. The feature is integral to power sequencing in multi-rail systems and is validated in Figure 2 test circuit.
What external components are mandatory for basic operation of the LM2574N-ADJ?
Four external components are mandatory: an inductor (e.g., 330 µH for 5V/0.5A), a Schottky catch diode (e.g., 1N5817), an input capacitor (≥22 µF aluminum electrolytic), and an output capacitor (≥220 µF aluminum electrolytic). These are specified in the Typical Application schematic (DS011394-12) and Design Procedure section. Resistor divider (R1/R2) is required only for adjustable output configuration - omitted for fixed-output versions.
LM2574N-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LM2574N-ADJ FAQ
1.How can I place an order for LM2574N-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574N-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 LM2574N-ADJ reliable?
The price and inventory of LM2574N-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2574N-ADJ is usually 5 days.
3.What payment methods are accepted for LM2574N-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574N-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574N-ADJ?
LM2574N-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574N-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 LM2574N-ADJ?
For technical support, including LM2574N-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574N-ADJ requirements.
6.How does Aetrix verify that LM2574N-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2574N-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 LM2574N-ADJ meets industry standards.
7.What is the process for return or replacement of LM2574N-ADJ?
All LM2574N-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2574N-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 LM2574N-ADJ part is unused and in its original packaging.
Return procedure for LM2574N-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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