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onsemi LM2574N-ADJ
- Part No.:
- LM2574N-ADJ
- Manufacturer:
- onsemi
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2574N-ADJ.pdf
- Description:
- IC REG BUCK BST ADJ 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:3,864
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Product details
Overview
LM2574N-ADJ from Texas Instruments is a monolithic non-synchronous step-down (buck) DC-DC switching regulator delivering up to 0.5 A output current with ±4% output voltage accuracy, 1.23 V to 37 V adjustable output range, and 52 kHz fixed-frequency operation. It serves as a high-efficiency replacement for linear regulators in industrial power supplies, embedded controllers, and on-card DC-DC conversion.
For engineers reviewing the LM2574N-ADJ datasheet, pinout, applications, or equivalent options, key selection criteria include its 40 V max input voltage (non-HV), PDIP-8 package thermal resistance (60.4°C/W), feedback reference voltage (1.23 V), and TTL-compatible ON/OFF control with 50 µA standby current.
Technical Context
The LM2574N-ADJ implements a fixed-frequency PWM controller with internal oscillator, error amplifier, and 0.5-A NPN power switch. Its feedback loop uses a precision 1.23 V bandgap reference and requires external resistor divider to set output voltage - no internal voltage reference is used for regulation except at the FB pin.
It operates in continuous or discontinuous conduction mode depending on load and inductor value, features cycle-by-cycle current limiting (1.0 A typical peak limit), thermal shutdown, and undervoltage lockout. The ON/OFF pin enables TTL-level shutdown with 1.2 V logic-low threshold and 1.4 V logic-high threshold.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | 0.5 A DC maximum - supports mid-power loads without external pass transistor or heatsink. |
| Input voltage range | 4.75 V to 40 V - compatible with 5 V, 12 V, 24 V, and 36 V industrial rails. |
| Output voltage range | 1.23 V to 37 V - set via external R1/R2 divider; FB pin voltage regulated to 1.23 V ±1.3%. |
| Oscillator frequency | 52 kHz ±10% - fixed frequency enables predictable EMI filtering and inductor selection. |
| Feedback reference | 1.23 V ±1.3% - defines output accuracy baseline; tolerance contributes directly to overall VOUT error. |
| Standby current | 50 µA typical - enables low-power shutdown in battery-backed or energy-sensitive systems. |
| Saturation voltage | 1.2 V max at 0.5 A - determines minimum dropout and impacts efficiency at low VOUT. |
| Thermal resistance | 60.4°C/W (PDIP-8, junction-to-ambient) - defines maximum power dissipation before thermal shutdown at 125°C. |
Pinout & Package
LM2574N-ADJ is supplied in an 8-pin plastic dual in-line package (PDIP), with exposed copper pad not present; thermal performance relies on PCB copper area connected to PWR_GND and SIG_GND pins.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FB | Feedback sense input | High-impedance input (100 nA bias) referenced to 1.23 V; connects to resistor divider midpoint to set VOUT. |
| 2 SIG_GND | Signal ground | Reference for internal bandgap, error amp, and logic; must be star-connected to minimize noise coupling. |
| 3 ON/OFF | Enable control input | TTL-compatible; <1.2 V = active, >1.4 V = shutdown; 50 µA standby draw when high. |
| 4 PWR_GND | Power ground | Return path for switch emitter current; must be low-inductance connection to CIN and COUT grounds. |
| 5 VIN | Input supply | Collector of internal NPN switch; accepts 4.75–40 V; requires local 22 µF electrolytic bypass. |
| 6–8 NC | No internal connection | Not bonded; may be grounded or left floating per layout best practice - no electrical function. |
| 7 OUTPUT | Switch emitter node | Switching node connecting to inductor and diode cathode; high dv/dt requires tight layout. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 52-kHz oscillator | Enables consistent EMI profile and simplifies filter design without external timing components. |
| Internal current limit | 1.0 A peak switch current limit protects against short-circuit and overload without external sensing. |
| Thermal shutdown | Activates at ~150°C junction temperature, latching off until cooldown - prevents permanent damage. |
| Low-component count | Requires only 4 external parts: input cap, output cap, inductor, and feedback divider - reduces BOM cost and footprint. |
| Standard inductor compatibility | Optimized for off-the-shelf shielded power inductors (e.g., 100–680 µH), avoiding custom magnetics. |
Applications
| Industrial Power Supply | Embedded Controller Board |
|---|---|
Use Scenario: Local 5 V or 12 V rail generation from 24 V factory bus in PLC I/O modules. IC Role / Device Role / Timing Role: Primary buck regulator providing stable, efficient DC-DC conversion with minimal external components. Use Value: Eliminates need for heat sinks due to 77%+ efficiency at 0.5 A, reducing board area and thermal management complexity. | Use Scenario: On-board 3.3 V supply for microcontroller, ADC, and interface ICs in remote sensor nodes. IC Role / Device Role / Timing Role: Adjustable-output buck converter configured for precise 3.3 V with ±4% regulation over line/load/temperature. Use Value: 1.23 V reference and resistor-based feedback enable accurate, low-cost voltage setting without trimming or calibration. |
| Positive-to-Negative Converter | Preregulator for Linear Regulator |
Use Scenario: Generating –5 V or –12 V from +12 V input in analog signal conditioning circuits. IC Role / Device Role / Timing Role: Buck-boost topology implementation using LM2574N-ADJ in inverting configuration. Use Value: Fixed 52 kHz frequency and robust current limit simplify negative rail design versus discrete solutions. | Use Scenario: Reducing 24 V input to 7 V intermediate rail before LDO for clean 5 V digital supply. IC Role / Device Role / Timing Role: High-efficiency preregulator minimizing power loss and heat in LDO pass element. Use Value: 0.5 A capability and 40 V input support wide input variation while maintaining regulation under dynamic load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596-ADJ | Higher 3 A output current, 150 kHz switching frequency, improved efficiency (up to 92%), but larger solution size and higher cost. | Better suited for higher-current (>0.75 A) or space-constrained designs requiring lower ripple. | Select LM2596-ADJ when load exceeds 0.5 A or when tighter output ripple (<100 mVpp) is required. |
| MP1584EN-LF-Z | 3 A output, 1.5 MHz switching, smaller external components, but requires careful layout for EMI and lacks integrated thermal shutdown flag. | Preferred for compact consumer-grade power supplies where PCB area is critical and thermal monitoring is optional. | Choose MP1584EN-LF-Z for high-density designs needing sub-1 mm height inductors and faster transient response. |
Compared with LM2574N-ADJ, LM2596-ADJ delivers 6× more output current and better efficiency but increases BOM count and layout sensitivity; MP1584EN-LF-Z offers modern high-frequency integration at the cost of reduced fault protection visibility and stricter layout requirements.
Availability
LM2574N-ADJ is available at Aetrix Electronics and suitable for industrial power supplies, embedded controller boards, positive-to-negative converters, and preregulator applications requiring stable component supply across extended temperature ranges and long production lifecycles.
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 is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with broad industrial and automotive reach.
The LM2574x SIMPLE SWITCHER® product line was designed for cost-sensitive, medium-power DC-DC conversion where ease of use, reliability, and minimal external component count outweigh ultra-high efficiency or miniaturization demands.
FAQ
What is the maximum input voltage rating for the LM2574N-ADJ?
The LM2574N-ADJ has a maximum supply voltage rating of 45 V (absolute maximum), with recommended operating input voltage up to 40 V. Exceeding 40 V continuously risks exceeding thermal limits or degrading long-term reliability, especially at elevated ambient temperatures. The LM2574N-ADJ is not the HV variant - for 60 V operation, the LM2574HV-ADJ must be used instead.
How do I calculate the output voltage for the LM2574N-ADJ?
The output voltage of the LM2574N-ADJ is set by an external resistor divider between VOUT, FB, and GND. Use the formula VOUT = 1.23 V × (1 + R1/R2), where R2 connects FB to GND and R1 connects VOUT to FB. The FB pin draws only 100 nA, so standard 1% metal-film resistors yield ±0.5% setting accuracy. For example, R1 = 10 kΩ and R2 = 1.02 kΩ yields 13.0 V output. This calculation applies directly to the LM2574N-ADJ.
Does the LM2574N-ADJ require an input capacitor, and what type is recommended?
Yes, the LM2574N-ADJ requires a minimum 22 µF aluminum electrolytic capacitor at the VIN pin, placed with short leads near the device. This capacitor stabilizes input voltage during switching transients and reduces EMI. At temperatures below −25°C, TI recommends paralleling a 1–10 µF ceramic capacitor to compensate for electrolytic capacitance loss and ESR rise. The RMS ripple current rating must exceed calculated values - failure to meet this spec risks premature capacitor failure in the LM2574N-ADJ circuit.
Can the LM2574N-ADJ be used in a buck-boost (inverting) configuration?
Yes, the LM2574N-ADJ supports buck-boost topology for generating negative output voltages from positive inputs. In this configuration, the OUTPUT pin drives the inductor, the diode anode connects to ground, and the output capacitor negative terminal becomes the regulated negative rail. Feedback is taken from the negative rail via an inverted resistor divider. This application is explicitly documented in the LM2574N-ADJ datasheet Figure 16 and is a validated use case - not a workaround.
What thermal considerations apply to the LM2574N-ADJ in PDIP-8 package?
The LM2574N-ADJ in PDIP-8 has a junction-to-ambient thermal resistance (RθJA) of 60.4°C/W. With a maximum junction temperature of 150°C and 25°C ambient, the allowable power dissipation is ~2.08 W. At 0.5 A output and 10 V dropout, power loss reaches ~5 W - requiring significant PCB copper area (≥4 cm² per GND pin) and possibly airflow. Derating is essential above 70°C ambient; the LM2574N-ADJ thermal shutdown activates at ~150°C to prevent damage.
LM2574N-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Buck-Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.75V
- 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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