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Microchip Technology LM2574-3.3YN
- Part No.:
- LM2574-3.3YN
- Manufacturer:
- Microchip Technology
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2574-3.3YN.pdf
- Description:
- IC REG BUCK 3.3V 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:273
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Product details
Overview
LM2574-3.3YN from Micrel, Inc. is a fixed-output 3.3V, 0.5A step-down (buck) switching regulator in an 8-pin plastic DIP package, featuring a 52kHz internal oscillator, ±4% output voltage accuracy over load and line, and integrated thermal shutdown and cycle-by-cycle current limiting. It delivers high-efficiency DC/DC conversion for embedded power rails requiring stable low-noise 3.3V supply.
For engineers reviewing the LM2574-3.3YN datasheet, LM2574-3.3YN pinout, LM2574-3.3YN application, or LM2574-3.3YN equivalent, key selection considerations include input voltage range (up to 40V), standby current (<200µA), output voltage tolerance (±4%), thermal protection behavior, and compatibility with standard off-the-shelf inductors and capacitors.
Technical Context
The LM2574-3.3YN integrates a 52kHz fixed-frequency oscillator, error amplifier with 1.23V internal reference, PWM comparator, and N-channel switch driver. Its architecture uses external diode, inductor, and capacitors to form a non-synchronous buck topology with duty-cycle control determined by feedback voltage at the FB pin.
It operates across –40°C to +85°C junction temperature, supports ON/OFF control via logic-level input (VIH ≥2.2V, VIL ≤1.2V), and guarantees 0.5A output current with saturation voltage ≤1.2V at full load. Internal frequency compensation eliminates need for external compensation components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±4% over 0.1–0.5A load and 4.75–40V input - ensures stable microcontroller core rail without external resistor divider. |
| Switching Frequency | 52kHz ±10% - enables use of low-cost, high-current standard inductors (e.g., 330µH) and simplifies EMI filtering design. |
| Max Output Current | 0.5A continuous - sufficient for powering DSPs, FPGAs I/O banks, or multiple low-power peripherals from a single regulator. |
| Input Voltage Range | 4.75V to 40V - supports wide-input industrial and automotive-derived supplies without pre-regulation. |
| Standby Current | <200µA typical - enables low-power sleep modes in battery-backed systems without significant quiescent drain. |
| Protection Features | Cycle-by-cycle current limit (0.7–1.6A peak) and thermal shutdown - prevents damage during short-circuit or overload without external sensing circuitry. |
Pinout & Package
LM2574-3.3YN is housed in an 8-pin plastic DIP (N) package with 0.3" width and through-hole mounting. Thermal performance relies on PCB copper area connected to all pins; no heatsink required under typical loads.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FB | Feedback Input | Monitors regulated output via internal 1.23V reference; not used in fixed 3.3V version - left unconnected per datasheet. |
| 2 SIG GND | Signal Ground | Reference ground for internal error amplifier and oscillator - must be routed separately from power ground to minimize noise coupling. |
| 3 ON/OFF | Enable/Shutdown Control | Logic-high (>2.2V) enables regulation; logic-low (<1.2V) disables output and reduces quiescent current to <200µA. |
| 4 PWR GND | Power Ground | High-current return path for switch node and output capacitor - connects directly to power plane or thick trace. |
| 5 VIN | Input Supply | Accepts 4.75–40V unregulated DC; requires local 22µF/40V input capacitor for stability and transient suppression. |
| 6 OUTPUT | Switch Node | Drives external catch diode and inductor; switches between VIN and GND at 52kHz - critical for layout EMI control. |
| 7 NC | No Connect | Internally unused pin - must remain unconnected; no routing or soldering required. |
| 8 NC | No Connect | Internally unused pin - must remain unconnected; no routing or soldering required. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 3.3V output | Eliminates external feedback resistors, reducing BOM count and layout sensitivity while guaranteeing ±4% accuracy across temperature and load. |
| Integrated 52kHz oscillator | Enables predictable switching behavior and consistent inductor sizing - avoids variability from external timing components. |
| Thermal shutdown + current limit | Provides autonomous fault recovery without external monitoring ICs - protects against sustained overloads and PCB overheating. |
| Low standby current | Supports system-level power gating: <200µA shutdown current allows long-term battery operation in maintenance or alarm-monitoring modes. |
| Minimal external parts | Requires only four components - input cap, output cap, inductor, and catch diode - accelerating prototyping and reducing board space. |
Applications
| Industrial Sensor Node Power | Embedded Microcontroller Core Rail |
|---|---|
|
Use Scenario: Remote temperature/humidity sensor node powered by 12V or 24V industrial bus with periodic wake-up and wireless transmission. IC Role / Device Role / Timing Role: Primary DC/DC buck regulator converting unregulated bus voltage to clean 3.3V for MCU, RF transceiver, and analog front-end. Use Value: High efficiency (>73% at 100mA) extends battery life; 52kHz switching avoids interference with sub-GHz ISM band; ON/OFF pin enables deep-sleep control. |
Use Scenario: Single-board controller in factory automation PLC module requiring reliable 3.3V supply for ARM Cortex-M4 core and peripherals. IC Role / Device Role / Timing Role: Main system regulator delivering 0.5A at 3.3V with tight line/load regulation to meet processor voltage tolerance specs. Use Value: ±4% output accuracy ensures compliance with 3.3V ±5% I/O voltage requirements; thermal shutdown prevents failure during ambient temperature spikes. |
| POS Terminal Power Management | Legacy Industrial Equipment Retrofit |
|
Use Scenario: Point-of-sale terminal with 12V wall adapter input, powering display, barcode scanner, and secure element. IC Role / Device Role / Timing Role: Step-down regulator supplying isolated 3.3V domain for security IC and touch controller interface. Use Value: Wide 4.75–40V input accommodates aging adapters with poor regulation; low standby current minimizes energy waste during idle periods. |
Use Scenario: Retrofitting obsolete linear regulators in legacy CNC machine control boards where heat dissipation was problematic. IC Role / Device Role / Timing Role: Drop-in replacement for inefficient 78L33, reducing board temperature rise and enabling higher ambient operating range. Use Value: 73–78% efficiency vs. ~40% for linear regulators cuts power loss by >50%, eliminating need for heatsinks and improving long-term reliability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2574-3.3W | Same electrical specs but in TO-220-5 package with exposed tab for enhanced thermal dissipation (θJA = 50°C/W vs. 85°C/W). | Better suited for continuous 0.5A loads in high-ambient environments (>60°C) or where forced-air cooling is unavailable. | Select LM2574-3.3W when thermal margin is constrained; LM2574-3.3YN remains optimal for cost-sensitive, space-constrained DIP layouts. |
| MP1584EN-LF-Z | Higher switching frequency (1.5MHz), smaller external components, but requires external compensation and lacks built-in current limit threshold specification. | Enables ultra-compact designs but demands more careful loop stability analysis and may require additional fault-handling circuitry. | Choose MP1584EN-LF-Z only if board area is critical and design team has experience with high-frequency buck compensation. |
Compared with LM2574-3.3W and MP1584EN-LF-Z, the LM2574-3.3YN offers the simplest implementation for moderate-power, cost-driven industrial applications - requiring no compensation, delivering guaranteed protection, and fitting legacy DIP footprints without layout revision.
Availability
LM2574-3.3YN is available at Aetrix Electronics and suitable for industrial sensor nodes, embedded microcontroller core rails, and POS terminal power management requiring stable component supply and long-lifecycle support.
Supply support for LM2574-3.3YN 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 LM2574 product line was designed for simple, robust, low-component-count DC/DC conversion in industrial, telecom, and embedded systems where reliability and ease of use outweighed ultra-high efficiency or miniaturization.
FAQ
What is the maximum input voltage rating for the LM2574-3.3YN?
The LM2574-3.3YN has an absolute maximum input voltage rating of 45V, but its recommended operating input voltage range is 4.75V to 40V. Exceeding 40V risks violating guaranteed performance specifications such as output voltage accuracy and efficiency, even if the device does not immediately fail. Always refer to the Electrical Characteristics table for test conditions specifying VIN = 12V and input ranges up to 40V.
Does the LM2574-3.3YN require external feedback resistors?
No, the LM2574-3.3YN is a fixed-output variant and does not require external feedback resistors. Its 3.3V regulation is achieved internally using a precision 1.23V reference and trimmed resistor network. The FB pin (Pin 1) must be left unconnected - unlike the adjustable LM2574 versions, which rely on external resistors to set output voltage.
How does the ON/OFF pin function on the LM2574-3.3YN?
The ON/OFF pin (Pin 3) controls enable/disable functionality: applying ≥2.2V (VIH) enables regulation, while ≤1.2V (VIL) places the LM2574-3.3YN into standby mode with quiescent current <200µA. This pin is TTL- and CMOS-compatible and draws only 4–30µA in OFF state, making it ideal for microcontroller GPIO control in low-power systems.
Can the LM2574-3.3YN be used in a positive-to-negative buck-boost configuration?
Yes, the LM2574-3.3YN can be configured as a positive-to-negative converter per Application Note AN-112 and Figure 5 in the original Micrel datasheet. In this topology, the OUTPUT pin drives an inductor to ground, and the negative output is taken across the output capacitor referenced to VIN. However, output voltage regulation and ripple performance differ from standard buck operation and require careful component selection.
What thermal management guidance applies to the LM2574-3.3YN in DIP package?
The LM2574-3.3YN in 8-pin DIP (N) package has a junction-to-ambient thermal resistance (θJA) of 85°C/W when mounted on a standard PCB with ~1 square inch of copper around the leads. No heatsink is required for 0.5A operation at ambient ≤50°C; however, thermal relief on all pins and generous copper pour on both layers significantly improves reliability and derating margins.
LM2574-3.3YN 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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- -
- 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:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LM2574-3.3YN FAQ
1.How can I place an order for LM2574-3.3YN through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574-3.3YN 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 LM2574-3.3YN reliable?
The price and inventory of LM2574-3.3YN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2574-3.3YN is usually 5 days.
3.What payment methods are accepted for LM2574-3.3YN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574-3.3YN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574-3.3YN?
LM2574-3.3YN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574-3.3YN 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 LM2574-3.3YN?
For technical support, including LM2574-3.3YN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574-3.3YN requirements.
6.How does Aetrix verify that LM2574-3.3YN is sourced from the original manufacturer or authorized distributors?
All LM2574-3.3YN 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 LM2574-3.3YN meets industry standards.
7.What is the process for return or replacement of LM2574-3.3YN?
All LM2574-3.3YN units undergo pre-shipment inspection (PSI). If there is an issue with LM2574-3.3YN, 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 LM2574-3.3YN part is unused and in its original packaging.
Return procedure for LM2574-3.3YN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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