My Inquiry
My Account
Microchip Technology LM2574BN
- Part No.:
- LM2574BN
- Manufacturer:
- Microchip Technology
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LM2574BN.pdf
- Description:
- IC REG BUCK ADJ 500MA 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,379
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LM2574BN from Micrel is an adjustable-output buck switching regulator IC delivering 0.5A output current with ±4% output voltage accuracy over line and load, operating from 4V to 40V input, featuring internal 52kHz oscillator and thermal shutdown protection. It serves as a compact, high-efficiency DC-DC step-down solution in industrial power supplies and embedded system rails.
For engineers reviewing the LM2574BN datasheet, LM2574BN pinout, LM2574BN application, or LM2574BN equivalent, key selection considerations include its fixed-frequency PWM architecture, ON/OFF control interface, feedback reference voltage of 1.23V, and DIP-8 package compatibility with through-hole prototyping and legacy board designs.
Technical Context
The LM2574BN integrates a 52kHz oscillator (±10%), error amplifier with 1.23V reference, current-limited NPN switch, and thermal shutdown circuitry. Its cycle-by-cycle current limiting triggers at 0.7–1.6A peak, and internal compensation eliminates need for external compensation networks.
It operates in continuous conduction mode with duty cycle up to 98%, supports external shutdown via TTL/CMOS-compatible ON/OFF pin, and maintains regulation down to minimum input voltage determined by dropout and duty cycle constraints - not a low-dropout linear regulator.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | Guaranteed 0.5A continuous output; enables single-stage conversion for mid-power rails without heatsink. |
| Input Voltage Range | 4V to 40V DC; supports wide-input industrial and automotive battery-supplied systems. |
| Feedback Reference | 1.23V ±2.7% over temperature; sets output voltage via resistor divider (VOUT = 1.23V × (1 + R1/R2)). |
| Oscillator Frequency | 52kHz ±10%; fixed frequency simplifies EMI filtering and allows use of standard off-the-shelf inductors. |
| Standby Current | <200µA typical when ON/OFF pin is high; enables low-power sleep modes in battery-backed systems. |
| Thermal Protection | Internal thermal shutdown activates at TJ ≥ 150°C; prevents damage during overload or poor PCB heat sinking. |
| Saturation Voltage | 0.8–1.4V at 0.5A; defines minimum dropout and impacts efficiency at low VIN/VOUT ratios. |
Pinout & Package
LM2574BN is housed in an 8-pin plastic DIP (N) package with 0.3" width, rated for –40°C to +85°C junction temperature. Pins are leaded for through-hole mounting and provide direct access to internal switch, feedback, and control nodes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 FB | Feedback Input | Connects to resistor divider; regulates output by comparing divided VOUT to 1.23V internal reference. |
| 2 GND (SIG) | Signal Ground | Analog ground reference for feedback and error amplifier; separate from power ground in layout best practice. |
| 3 ON/OFF | Shutdown Control | TTL/CMOS-compatible input; logic high disables switching, reducing quiescent current to <200µA. |
| 4 GND (PWR) | Power Ground | High-current return path for internal switch and external catch diode; should be tied to SIG GND at single point. |
| 5 VIN | Input Supply | DC input supply (4–40V); requires local 22µF/40V capacitor for stability and transient response. |
| 6 OUTPUT | Switch Node | Collector of internal NPN transistor; connects to inductor and catch diode anode in buck topology. |
| 7 NC | No Connect | Internally unused; must remain unconnected per datasheet. |
| 8 NC | No Connect | Internally unused; must remain unconnected per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 52kHz Oscillator | Eliminates external timing components; ensures consistent switching frequency for predictable EMI and filter design. |
| Current-Limited Switch | Peak current limit of 0.7–1.6A protects against short-circuit and inductor saturation failures. |
| Thermal Shutdown | Automatically disables regulator at 150°C junction temperature; recovers after cooldown without latch-up. |
| ON/OFF Logic Interface | Direct TTL/CMOS-compatible enable/disable control; supports system-level power sequencing and standby states. |
| Internal Compensation | Reduces external component count to only four: input cap, output cap, inductor, and feedback divider. |
Applications
| Industrial Power Rails | Embedded System DC-DC Conversion |
|---|---|
|
Use Scenario: Providing stable 5V or 12V rail from 24V industrial bus in PLC I/O modules. IC Role / Device Role / Timing Role: Primary buck regulator converting unregulated 24V to isolated 5V logic supply. Use Value: Delivers 0.5A with <78% efficiency at 12VIN/5VOUT, eliminating need for heatsink in enclosed enclosures. |
Use Scenario: Generating 3.3V core voltage for microcontrollers in battery-powered sensor nodes. IC Role / Device Role / Timing Role: Adjustable buck converter configured for 3.3V output with shutdown control. Use Value: Standby current <200µA extends battery life; 52kHz operation avoids audible noise in portable devices. |
| On-Card Pre-Regulator | Positive-to-Negative Converter |
|
Use Scenario: Reducing 40V input to 12V intermediate rail before LDO post-regulation in telecom equipment. IC Role / Device Role / Timing Role: High-input-voltage pre-regulator minimizing power dissipation in downstream linear regulators. Use Value: Supports up to 40V input with guaranteed 0.5A output, improving overall system efficiency vs. single-stage LDO. |
Use Scenario: Generating –5V bias supply from +12V rail in op-amp signal conditioning circuits. IC Role / Device Role / Timing Role: Buck-boost topology implementation using LM2574BN's switch node and external components. Use Value: Leverages internal 52kHz oscillator and current limit for reliable inverting operation without additional controller IC. |
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 architecture but rated for –40°C to +125°C junction range; higher thermal resistance (θJA = 85°C/W same). | Required for extended-temperature industrial or under-hood automotive environments where ambient exceeds 85°C. | Select LM2574HVN when operating junction temperature may exceed +85°C; otherwise LM2574BN suffices for commercial-grade designs. |
| LM2596-ADJ | Higher 3A output current, 150kHz switching frequency, and improved line/load regulation (±1.5%); different pinout and compensation. | Used where higher current or tighter regulation is needed; requires PCB redesign due to non-pin-compatible layout. | Choose LM2596-ADJ only if >0.5A output or better than ±4% accuracy is required; LM2574BN remains optimal for cost-sensitive, space-constrained 0.5A applications. |
Compared with LM2574HVN and LM2596-ADJ, the LM2574BN offers the lowest BOM count and simplest layout for 0.5A buck conversion at 52kHz, balancing thermal robustness, ease of use, and legacy DIP compatibility - making it ideal for maintenance, replacement, and low-volume industrial designs.
Availability
LM2574BN is available at Aetrix Electronics and suitable for industrial power rails, embedded system DC-DC conversion, and on-card pre-regulator applications requiring stable component supply, long-term obsolescence management, and through-hole assembly support.
Supply support for LM2574BN 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 LM2574BN belongs to Micrel's legacy buck regulator product line, designed for simplicity and reliability in cost-sensitive, medium-current DC-DC conversion where minimal external components and proven thermal behavior are critical.
FAQ
What is the maximum input voltage rating for the LM2574BN?
The LM2574BN has an absolute maximum input voltage rating of 45V, but its recommended operating input voltage range is 4V to 40V DC. Exceeding 40V during normal operation risks violating guaranteed performance specifications such as line regulation and thermal limits. The 40V upper bound ensures reliable operation across the full –40°C to +85°C temperature range with proper PCB layout and thermal management.
Does the LM2574BN require external compensation components?
No, the LM2574BN includes internal frequency compensation, so no external compensation network is needed. This reduces design complexity and component count to just four external parts: input capacitor, output capacitor, power inductor, and feedback resistor divider. The internal compensation is optimized for standard buck configurations using typical inductor values (e.g., 330µH) and output capacitors (e.g., 220µF).
Can the LM2574BN be used in a buck-boost configuration?
Yes, the LM2574BN can be configured as a buck-boost converter by reusing its internal switch node (pin 6) in an inverting topology with appropriate external components - including an inductor, diode, and output capacitor arranged per standard buck-boost schematics. The datasheet explicitly lists "positive to negative converter (buck-boost)" as a supported application, leveraging the same 52kHz oscillator and current-limit protection.
What is the purpose of the two ground pins (pins 2 and 4) on the LM2574BN?
Pins 2 (SIG GND) and 4 (PWR GND) serve separate functions: SIG GND is the analog reference for the feedback amplifier and error comparator, while PWR GND carries high-pulse currents from the internal switch and external catch diode. Separating these grounds minimizes noise coupling into the feedback path and improves regulation accuracy. They must be connected at a single point near the IC to avoid ground loops.
Is the LM2574BN RoHS-compliant?
The LM2574BN part number corresponds to the standard (non-Pb-free) version per Micrel's ordering information table. Pb-free variants are designated with a "Y" suffix (e.g., LM2574YN). Therefore, LM2574BN is not RoHS-compliant unless specifically sourced as a Pb-free variant - always verify the suffix and packaging markings, as RoHS compliance depends on the exact orderable part number and date code.
LM2574BN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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
LM2574BN FAQ
1.How can I place an order for LM2574BN through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2574BN 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 LM2574BN reliable?
The price and inventory of LM2574BN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2574BN is usually 5 days.
3.What payment methods are accepted for LM2574BN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2574BN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2574BN?
LM2574BN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2574BN 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 LM2574BN?
For technical support, including LM2574BN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2574BN requirements.
6.How does Aetrix verify that LM2574BN is sourced from the original manufacturer or authorized distributors?
All LM2574BN 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 LM2574BN meets industry standards.
7.What is the process for return or replacement of LM2574BN?
All LM2574BN units undergo pre-shipment inspection (PSI). If there is an issue with LM2574BN, 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 LM2574BN part is unused and in its original packaging.
Return procedure for LM2574BN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM2574BN Tags
-
TPS562201DDCR
Texas Instruments
-
MC34063ABD-TR
STMicroelectronics
-
TPS561201DDCR
Texas Instruments
-
MC33063ADR
Texas Instruments
-
MC34063ADR
Texas Instruments
-
TPS560200DBVR
Texas Instruments
-
AP3012KTR-G1
Diodes Incorporated
-
TLV61048DBVR
Texas Instruments
-
AZ34063UMTR-G1
Diodes Incorporated
-
TPS562200DDCR
Texas Instruments
-
AP62300TWU-7
Diodes Incorporated
-
MC34063EBD-TR
STMicroelectronics
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
