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Microchip Technology LM2574YN
- Part No.:
- LM2574YN
- Manufacturer:
- Microchip Technology
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2574YN.pdf
- Description:
- IC REG BUCK ADJ 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,927
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Product details
Overview
LM2574YN from Micrel, Inc. is a fixed-frequency 52kHz step-down (buck) switching regulator IC in 8-pin DIP package, delivering up to 0.5A output current with ±4% output voltage accuracy, 40V maximum input voltage, and integrated thermal shutdown and cycle-by-cycle current limiting. It serves as a primary DC-DC conversion stage in industrial power supplies requiring compact, low-component-count regulation.
For engineers reviewing the LM2574YN datasheet, LM2574YN pinout, LM2574YN application, or LM2574YN equivalent, key selection criteria include its 52kHz fixed oscillator frequency, 0.5A guaranteed output capability, 8-pin DIP thermal performance without heatsink, ON/OFF control interface, and compatibility with standard off-the-shelf inductors.
Technical Context
The LM2574YN integrates a 52kHz internal oscillator, error amplifier with 1.23V reference, PWM comparator, and NPN output switch with built-in current limit and thermal shutdown. Its architecture uses external diode, inductor, and capacitors to form a classic buck topology with minimal external parts.
It operates across –40°C to +85°C junction temperature range, supports input voltages up to 40V, and achieves typical efficiency of 78% at 12VIN/5VOUT/100mA. Standby quiescent current is below 200µA when the ON/OFF pin is high.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Guaranteed 0.5A continuous output-supports mid-power embedded rails without derating. |
| Oscillator Frequency | Fixed 52kHz ±10%-enables predictable EMI filtering and use of low-cost, standard 330µH inductors. |
| Input Voltage Range | 4.75V to 40V-compatible with 12V/24V industrial bus inputs and unregulated wall adapters. |
| Output Voltage Accuracy | ±4% over line/load/temperature-meets tight tolerance requirements for analog subsystems and MCU cores. |
| Standby Current | <200µA typical-enables low-power sleep modes in battery-backed or energy-conscious systems. |
| Thermal Protection | Integrated thermal shutdown-prevents latch-up or damage during overload or poor PCB heat sinking. |
| Current Limit | Peak 0.7–1.6A cycle-by-cycle-provides robust short-circuit protection without external sensing. |
Pinout & Package
LM2574YN is housed in an 8-pin plastic DIP (N) package with 0.3" width, rated for –40°C to +85°C operation. Thermal resistance θJA is 85°C/W with standard PCB copper layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FB | Feedback Input | Connects to resistor divider for adjustable versions; tied directly to output for fixed versions-sets regulated voltage via 1.23V internal reference. |
| 2 GND (SIG) | Signal Ground | Analog ground reference for feedback and oscillator-must be separated from power ground in noise-sensitive layouts. |
| 3 ON/OFF | Enable Control Input | Active-low logic interface: ≤0.8V enables, ≥2.2V disables-allows microcontroller or system-level power sequencing. |
| 4 GND (PWR) | Power Ground | High-current return path for switch node and output capacitor-requires low-inductance connection to minimize ringing. |
| 5 VIN | Input Supply | Unregulated DC input (up to 40V)-requires local 22µF/40V ceramic or electrolytic bypass near pin. |
| 6 OUTPUT | Switch Node | Drives external catch diode and inductor-rises to VIN during OFF time; connects to inductor cathode. |
| 7 NC | No Connect | Not internally bonded-must remain unconnected per datasheet; no routing or pull-up/pull-down. |
| 8 NC | No Connect | Not internally bonded-must remain unconnected; floating pin has no electrical function. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 52kHz Oscillator | Eliminates external timing components and ensures stable switching frequency across temperature and load. |
| Internal Current Limit & Thermal Shutdown | Provides autonomous fault recovery without external circuitry-reduces BOM count and improves reliability. |
| ON/OFF Logic Control | Enables precise system-level power management with <200µA standby current-ideal for wake-on-event designs. |
| Minimal External Components | Requires only four passive parts (inductor, diode, input/output caps)-reduces design risk and accelerates prototyping. |
| Fixed-Frequency PWM Operation | Simplifies EMI filter design and avoids subharmonic instability common in current-mode controllers. |
Applications
| Industrial Power Supplies | Embedded System Pre-regulators |
|---|---|
|
Use Scenario: Converting 24V rail to 5V for PLC I/O modules operating in harsh factory environments. IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, efficient, and thermally robust DC-DC conversion. Use Value: Delivers 0.5A at 78% efficiency with no heatsink required-reducing enclosure size and cost while meeting EN 61000-6-4 emissions. |
Use Scenario: Generating 3.3V from 12V for ARM Cortex-M microcontrollers in networked edge sensors. IC Role / Device Role / Timing Role: Pre-regulator feeding low-noise LDOs-reducing thermal load on final linear stage. Use Value: Enables >90% total system efficiency by minimizing LDO dropout loss, with 52kHz switching allowing small 330µH inductor. |
| On-Board DC-DC Conversion | Positive-to-Negative Buck-Boost Converters |
|
Use Scenario: Local 5V supply generation on motor drive control boards where space and component count are constrained. IC Role / Device Role / Timing Role: Compact, self-contained buck controller replacing discrete transistor-based solutions. Use Value: Reduces bill-of-materials to four passives and eliminates gate driver design-cutting layout time and validation effort. |
Use Scenario: Deriving –5V bias for op-amp signal conditioning stages in instrumentation front-ends. IC Role / Device Role / Timing Role: Configured in inverting buck-boost topology using same external components as buck mode. Use Value: Leverages identical 330µH inductor and 220µF output cap-minimizing inventory and enabling dual-rail design reuse. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2574HVN | Same pinout and function, but rated for –40°C to +125°C junction temperature and higher input voltage (45V abs max). | Required for under-hood automotive or high-ambient industrial deployments exceeding 85°C ambient. | Select LM2574HVN when extended temperature operation or higher absolute max input voltage margin is needed. |
| LM2596-5.0 | Higher 3A output current, 150kHz switching frequency, and improved line/load regulation (±2%), but requires different inductor value and layout. | Better suited for higher-power loads (>0.5A) or tighter regulation specs; not drop-in compatible due to frequency and compensation differences. | Choose LM2596-5.0 only when upgrading output capability or regulation accuracy-requires full revalidation of LC filter and feedback loop. |
Compared with LM2574HVN and LM2596-5.0, the LM2574YN offers optimal balance of simplicity, thermal performance in DIP packaging, and proven reliability for 0.5A industrial applications-without demanding higher-frequency layout discipline or extended-temperature qualification costs.
Availability
LM2574YN is available at Aetrix Electronics and suitable for industrial power supplies, embedded system pre-regulators, and on-board DC-DC conversion requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM2574YN 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
Micrel, Inc. was a U.S.-based semiconductor company specializing in analog, power management, and timing solutions before its acquisition by Microchip Technology in 2015.
The LM2574YN belongs to Micrel's legacy buck regulator product line, designed specifically for cost-sensitive, medium-current industrial and embedded applications where simplicity, reliability, and minimal external components are critical.
FAQ
What is the maximum input voltage rating for the LM2574YN?
The LM2574YN has an absolute maximum input voltage rating of 45V, but its recommended operating input voltage is up to 40V. Exceeding 40V may compromise long-term reliability or regulation accuracy, especially under high-temperature conditions. The LM2574YN maintains stable 5V or adjustable output regulation across this full 40V range when properly heatsunk on a PCB with adequate copper area.
Does the LM2574YN require an external diode, and what type is recommended?
Yes, the LM2574YN requires an external catch diode connected between the OUTPUT pin and the output capacitor's positive terminal. A Schottky diode such as the 1N5822 (3A, 40V) is recommended for efficiency and fast recovery. The diode must handle peak currents up to 1.6A and sustain reverse voltage equal to the input voltage-critical for reliable operation in buck and inverting configurations.
Can the LM2574YN be used in adjustable-output configurations?
Yes, the LM2574YN is the base part number for the adjustable version of the LM2574 family. When configured with resistive feedback from the OUTPUT pin to FB (pin 1), it delivers a regulated output from 1.23V to 37V with ±4% accuracy. Fixed-output variants like LM2574-5.0YN integrate the feedback divider internally, but the LM2574YN retains full adjustability via external resistors.
What is the thermal performance of the LM2574YN in its 8-pin DIP package?
The LM2574YN in 8-pin DIP (N) package has a junction-to-ambient thermal resistance (θJA) of 85°C/W with ~1 square inch of PCB copper surrounding the leads. At 0.5A output and 12V input, typical power dissipation is ~1.2W-resulting in ~102°C junction rise above ambient. This remains within the 150°C max junction limit if ambient stays below 48°C, eliminating need for external heatsinks in most industrial enclosures.
How does the ON/OFF pin function on the LM2574YN, and what logic levels enable operation?
The ON/OFF pin (pin 3) is an active-low enable input. Driving it to ≤0.8V (typical VIL) enables the LM2574YN; pulling it to ≥2.2V (typical VIH) places the device in standby mode with quiescent current below 200µA. The pin draws only 10µA max in either state, making it compatible with open-drain GPIO or simple transistor switches-enabling flexible power sequencing in multi-rail systems.
LM2574YN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- -
- 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
LM2574YN FAQ
1.How can I place an order for LM2574YN through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574YN 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 LM2574YN reliable?
The price and inventory of LM2574YN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2574YN is usually 5 days.
3.What payment methods are accepted for LM2574YN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574YN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574YN?
LM2574YN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574YN 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 LM2574YN?
For technical support, including LM2574YN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574YN requirements.
6.How does Aetrix verify that LM2574YN is sourced from the original manufacturer or authorized distributors?
All LM2574YN 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 LM2574YN meets industry standards.
7.What is the process for return or replacement of LM2574YN?
All LM2574YN units undergo pre-shipment inspection (PSI). If there is an issue with LM2574YN, 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 LM2574YN part is unused and in its original packaging.
Return procedure for LM2574YN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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