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HomeProductsCircuit ProtectionFuses0459.250UR
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0459.250UR - Littelfuse Inc.

Manufacturer Part Number
0459.250UR
Manufacturer
Littelfuse
Allelco Part Number
32D-0459.250UR
Warranty
1 Year Allelco Warranty - Find out more
Stock Status:
22,506 pcs available, New & Original
Parts Description
FUSE BOARD MNT 250MA 125VAC/VDC
Package
2-SMD, J-Lead
Data sheet
0459.250UR.pdf
RoHs Status
ROHS3 Compliant
Compare
Our certification
In stock: 22506
  • Unit Price: $0.97
  • Subtotal: $0.00

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Add to Cart and Submit RFQ now, we'll contact you immediately.

Quantity Unit Price Ext. Price
1+ $0.97 $0.97
10+ $0.875 $8.75
30+ $0.819 $24.57
100+ $0.762 $76.20
500+ $0.735 $367.50
1000+ $0.724 $724.00
The above prices does not include taxes and freight rates, which will be calculated on the order pages.

Specifications

0459.250UR Tech Specifications
Littelfuse Inc. - 0459.250UR technical specifications, attributes, parameters and parts with similar specifications to Littelfuse Inc. - 0459.250UR

Product Attribute Attribute Value
Manufacturer Littelfuse
Voltage Rating - DC 125 V
Voltage Rating - AC 125 V
Size / Dimension 0.285' L x 0.170' W x 0.120' H (7.24mm x 4.32mm x 3.05mm)
Series PICO® 459
Response Time Fast Blow
Package / Case 2-SMD, J-Lead
Package Tape & Reel (TR)
Operating Temperature -55°C ~ 125°C
Product Attribute Attribute Value
Mounting Type Surface Mount
Melting I²t 0.0106
Fuse Type Board Mount (Cartridge Style Excluded)
DC Cold Resistance 0.665 Ohms
Current Rating (Amps) 250 mA
Color -
Breaking Capacity @ Rated Voltage 50A AC, 300A DC
Approval Agency CSA, UL

Environmental & Export Classifications

ATTRIBUTE DESCRIPTION
RoHs Status ROHS3 Compliant
Moisture Sensitivity Level (MSL) 1 (Unlimited)
REACH Status REACH Unaffected
ECCN EAR99
HTSUS 8536.10.0040

Parts Introduction

0459.250UR Image
0459.250UR (1)

Manufacturer Part Number

250UR

Manufacturer

littelfuse

Introduction

The littelfuse 0459.250UR is a high-performance surface mount circuit protection fuse that offers reliable and efficient overcurrent protection for a wide range of electronic applications. This fuse features a compact and space-saving design, making it ideal for use in various electronic devices and systems.

Product Features and Performance

Fast-acting, fast-blow response time for quick circuit protection

High breaking capacity of 50A AC and 300A DC to handle high fault currents

Designed for surface mount (SMD) installation for easy integration into PCBs

Voltage ratings of 125V AC and 125V DC for versatile application

Operating temperature range of -55°C to 125°C for reliable performance in diverse environments

Product Advantages

Compact and space-saving design for efficient use of board space

Robust and reliable circuit protection to safeguard electronic components

Fast-acting response time to prevent damage from overcurrent events

High breaking capacity for handling high fault currents

Key Reasons to Choose This Product

Reliable and efficient circuit protection for a wide range of electronic applications

Compact and space-saving design for easy integration into tight spaces

Robust and durable construction for long-lasting performance

Wide operating temperature range for use in diverse environmental conditions

Compliance with industry safety standards (CSA and UL) for quality assurance

Quality and Safety Features

Compliance with CSA and UL safety standards for quality assurance

Robust and durable construction for reliable long-term performance

Rigorous testing and quality control measures to ensure product reliability

Compatibility

The littelfuse 0459.250UR fuse is compatible with a variety of electronic devices and systems that require overcurrent protection, including:

Portable electronics

Industrial control systems

Consumer electronics

Telecommunications equipment

Automotive electronics

Application Areas

Power supply circuits

Motor control circuits

Sensor and instrumentation systems

Telecommunications and networking equipment

Automotive and transportation applications

Product Lifecycle

The littelfuse 0459.250UR is an active and currently available product. There are no known equivalent or alternative models available at this time. If you have any questions or need further assistance, please contact our website's sales team.

Frequently Asked Questions(FAQ)

How does the Littelfuse 0459.250UR PICO® 459 fuse compare to traditional cartridge-style fuses in terms of current interruption capability at DC voltage, and what design implications does this have for high-reliability PCB applications?
The 0459.250UR provides a breaking capacity of 300A DC at its rated voltage of 125 VDC, significantly higher than many standard cartridge fuses which typically offer only 1–2 kA DC ratings. This enhanced DC interruption performance reduces the risk of sustained arcing during fault conditions in DC-powered systems such as battery management circuits or power conversion stages. When integrating into space-constrained PCBs, engineers benefit from its surface-mount form factor while maintaining robust protection capabilities comparable to larger through-hole solutions. The fast-blow response ensures rapid disconnection during overcurrent events, minimizing thermal stress on downstream components.
What is the practical significance of the 0.665 Ohms DC cold resistance value for the 0459.250UR, and how might it affect system efficiency in low-power embedded designs?
With a DC cold resistance of 0.665 Ohms, the 0459.250UR dissipates approximately 96 mW when carrying its full continuous current of 250 mA (I²R = 0.25² × 0.665). While this power loss may seem minor, in thermally sensitive environments or densely populated boards where heat buildup must be minimized, even small resistive losses can influence junction temperatures of nearby ICs or connectors. For battery-operated devices with strict power budgets, this cumulative dissipation should be factored into thermal simulations and overall energy budgeting. However, given the component’s compact size and efficient J-lead packaging, it remains suitable for most modern low-voltage digital systems without significant derating concerns.
In what scenarios would the Melting I²t value of 0.0106 for the 0459.250UR necessitate coordination with upstream overcurrent protection devices?
The Melting I²t of 0.0106 indicates that the fuse requires 10.6 mWs to initiate melting under short-circuit conditions. This relatively low threshold means the 0459.250UR responds quickly to transient surges but may not withstand benign overloads that last longer than a few milliseconds. Therefore, in applications like USB-powered peripherals or IoT sensor nodes, where surge immunity is critical, proper coordination with upstream polyfuses or resettable devices becomes essential. If the system experiences repeated moderate overloads below the fuse’s clearing curve, the fast-blow nature could lead to nuisance tripping unless filtered or buffered appropriately by preceding circuitry.
Why is the 0459.250UR suitable for industrial control systems requiring both UL and CSA approval, and what compliance advantages does this dual certification provide?
Dual certification to UL and CSA standards ensures that the 0459.250UR meets stringent safety requirements across North American markets, reducing regulatory hurdles for manufacturers deploying equipment in commercial or institutional environments. These agencies test not only dielectric strength and material flammability but also long-term reliability under thermal cycling and humidity exposure—critical factors in harsh industrial settings. For designers finalizing product certifications, using a pre-approved component like the 0459.250UR accelerates time-to-market and simplifies documentation for safety reviews.
How should the operating temperature range of -55°C to 125°C influence placement decisions for the 0459.250UR in automotive-grade versus consumer electronics?
Although the 0459.250UR supports an extended temperature range up to 125°C, automotive applications often require tighter thermal margins due to prolonged exposure to engine bay heat or direct sunlight. While the component itself is qualified for such extremes, its performance—particularly the DC cold resistance and response time—may drift outside specified tolerances if subjected to sustained peak temperatures near 125°C. In contrast, consumer electronics typically operate well within this range, allowing more flexible layout choices. Designers should still ensure adequate airflow or thermal isolation around the device, especially in enclosed enclosures or high-density assemblies.
Can the 0459.250UR be used interchangeably with other members of the PICO® 459 series in mixed-current designs, and what risks arise from mismatched current ratings?
The 0459.250UR is part of a broader family within the PICO® 459 series, sharing identical package dimensions and voltage ratings, making physical substitution feasible. However, substituting a 250 mA-rated fuse with one of a different nominal current—such as 500 mA or 1 A—without recalculating fault current thresholds and response curves can compromise system protection strategy. A lower-rated fuse may clear too aggressively during inrush transients, while a higher-rated unit might fail to protect sensitive loads adequately. Therefore, even within the same series, current rating coordination remains essential for safe and reliable operation.
What role does the Tape & Reel packaging play in automated assembly processes involving the 0459.250UR, and how does MSL 1 classification simplify handling logistics?
Tape & Reel packaging enables fully automated pick-and-place processing, improving production throughput and minimizing manual handling errors during SMT manufacturing. Combined with Moisture Sensitivity Level (MSL) 1 classification—indicating unlimited shelf life without drying requirements—the 0459.250UR simplifies inventory management and storage protocols. This combination is particularly advantageous for high-volume contract manufacturers aiming to reduce cycle times and avoid unnecessary pre-bake steps, ultimately lowering per-unit costs in mass-produced electronic goods.
How does the surface-mount J-lead configuration of the 0459.250UR impact solder joint reliability compared to gull-wing leads in vibration-prone environments?
The J-lead style promotes better coplanarity during reflow soldering and offers mechanical compliance under thermal expansion, enhancing resistance to fatigue cracking in thermally stressed joints. In automotive or aerospace applications subject to cyclic temperature changes, this design characteristic helps maintain connection integrity over the component’s lifetime. While not inherently superior to all lead types in every scenario, the J-lead’s inherent flexibility makes the 0459.250UR more resilient than some rigid leadframe variants when mounted on materials with mismatched CTE, such as FR4 PCBs exposed to wide ambient swings.
Is the 0459.250UR appropriate for use in Class II power supplies with isolated outputs, and why or why not?
Yes, the 0459.250UR is well-suited for Class II power supplies due to its 125 VAC/VDC working voltage and robust insulation properties validated by UL and CSA testing. Class II devices rely on double or reinforced insulation rather than grounding, so the fuse must operate safely under fault conditions without compromising isolation barriers. The 0459.250UR’s solid-state construction and absence of internal arcing during interruption support this requirement, provided the PCB layout maintains proper creepage and clearance distances per IEC 60950 or IEC 62368 standards.
What considerations apply when selecting between the 0459.250UR and ceramic-based resettable PTCs for overcurrent protection in space-limited consumer audio amplifiers?
While ceramic PTCs offer automatic recovery, they exhibit higher steady-state resistance and generate more heat during tripped states, potentially affecting amplifier bias stability or requiring additional cooling. In contrast, the 0459.250UR provides precise, single-use interruption with minimal post-fault resistance variation, preserving signal fidelity and simplifying fault diagnostics. For non-recurring faults or where reset functionality adds complexity, the discrete fuse solution proves more predictable and easier to verify during troubleshooting. However, if frequent nuisance trips are expected, a coordinated PTC-fuse combination may offer better robustness.
How does the RoHS3 and REACH compliance status of the 0459.250UR align with global environmental regulations, particularly in EU and California markets?
RoHS3 compliance confirms the absence of restricted substances including lead, mercury, cadmium, and certain phthalates, meeting stricter thresholds introduced after RoHS2. REACH Unaffected status further assures that the component contains no SVHCs (Substances of Very High Concern) above mandated thresholds, easing export documentation for European and Californian distributors. This dual compliance streamlines supply chain audits and avoids potential market access restrictions, making the 0459.250UR a reliable choice for multinational OEMs seeking consistent regulatory alignment across jurisdictions.
Given its 50A AC breaking capacity, can the 0459.250UR reliably interrupt fault currents in AC mains-powered appliances, or is it limited to auxiliary circuits?
No, the 0459.250UR is not intended for direct interruption of primary AC mains currents, even though its 50A AC rating appears sufficient for many household loads. Primary protection in mains applications requires fuses with specialized arc-quenching structures, higher interrupting ratings, and rigorous certification beyond basic board-mount components. Instead, the 0459.250UR is optimized for secondary-side protection in isolated power supplies or auxiliary circuits where fault energies are contained and controlled. Using it in primary mains roles could result in catastrophic failure, fire hazard, or non-compliance with electrical safety codes.
What trade-offs exist between using the 0449.250UR (if available) versus the 0459.250UR in high-humidity environments, based on their shared specifications?
Assuming both share identical electrical characteristics, differences in performance under humidity stress would depend on packaging details not specified here. However, since the 0459.250UR carries MSL 1 and is RoHS3 compliant, it likely incorporates protective coatings or materials resistant to moisture ingress. Without explicit comparative data on leakage current behavior or insulation resistance degradation, engineers should consult manufacturer application notes for humidity testing results. Generally, surface-mount fuses with sealed encapsulations outperform unsealed alternatives in damp conditions, but empirical validation remains necessary for mission-critical designs.
How does the 0459.250UR’s physical footprint (7.24mm x 4.32mm x 3.05mm) influence routing density in high-pin-count FPGA boards?
At less than 15 mm² of board area, the 0459.250UR occupies minimal real estate, enabling dense layouts without compromising signal integrity or increasing layer count. Its rectangular shape allows parallel alignment with traces, minimizing stub effects or impedance discontinuities in power delivery networks. When protecting multiple rails from a central power source, several units can be placed along adjacent rows without crowding vias or decoupling capacitors, supporting efficient PDN design. This compactness, combined with surface mounting, enhances manufacturability and reduces parasitic inductance compared to radial-leaded equivalents.
Are there any limitations in using the 0459.250UR in intrinsically safe circuits requiring certified explosion-proof protection?
Intrinsically safe circuits demand components rated specifically for hazardous locations (e.g., Zone 0/1) with certified containment of sparks or arcs. The 0459.250UR lacks such certification (only UL/CSA general-purpose), meaning its internal energy release during interruption could violate safety barriers in explosive atmospheres. For these environments, only fuses explicitly approved for use in ATEX/IECEx zones should be deployed. Thus, while the 0459.250UR excels in industrial control or telecom gear, it is unsuitable for oil/gas, mining, or chemical processing applications without supplementary containment measures.
What diagnostic value does the fast-blow response of the 0459.250UR provide in fault-tolerant computing platforms?
Fast-blow characteristics enable rapid detection of latent faults before they propagate to critical subsystems, allowing supervisory logic to log events and initiate graceful shutdown sequences. In redundant architectures where one rail fails, the quick interruption prevents cascading failures and preserves data integrity during transition phases. Unlike slow-blow fuses that tolerate brief surges, the 0459.250UR ensures immediate isolation, which is vital in server PSUs or edge AI devices where thermal runaway or voltage droop must be halted within microseconds to avoid permanent damage.
Does the absence of color coding on the 0459.250UR impact visual inspection or traceability during rework operations?
Color coding is uncommon in surface-mount fuses due to manufacturing constraints and limited differentiation utility at micro-scale sizes. Instead, traceability relies on laser-marked part numbers, batch codes, and fiducial alignment. Since the 0459.250UR includes its full model number (0459.250UR) in machine-readable form during reel labeling, automated optical inspection systems can verify placement accuracy and orientation effectively. Manual inspectors benefit from standardized orientation marks and polarity indicators, ensuring correct reinstallation during repair cycles without relying solely on visual cues like color.

Parts with Similar Specifications

The three parts on the right have similar specifications to Littelfuse Inc. 0459.250UR

Product Attribute 0459.200UR 0459.125UR 0459.250ER 0459.750UR
Part Number 0459.200UR 0459.125UR 0459.250ER 0459.750UR
Manufacturer Littelfuse Inc. Littelfuse Inc. Littelfuse Inc. Littelfuse Inc.
Approval Agency - - - -
Fuse Type - - - -
Size / Dimension - - - -
Response Time - - - -
Current Rating (Amps) - - - -
Mounting Type - Surface Mount Through Hole Surface Mount
DC Cold Resistance - - - -
Package / Case - 196-LFBGA 16-DIP (0.300', 7.62mm) 64-VFQFN Exposed Pad
Breaking Capacity @ Rated Voltage - - - -
Voltage Rating - AC - - - -
Color - - - -
Operating Temperature - -40°C ~ 85°C 0°C ~ 70°C -40°C ~ 85°C
Series - - - -
Voltage Rating - DC - - - -
Package - Tape & Reel (TR) Tube Tape & Reel (TR)
Melting I²t - - - -

0459.250UR Datasheet PDF

Download 0459.250UR pdf datasheets and Littelfuse Inc. documentation for 0459.250UR - Littelfuse Inc..

Datasheets
Cylindrical Battery Holders.pdf

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Customer Reviews

Evaluation: 10 Articles

  • ECUb***h
    Sep 22, 2026

    Used for repair of an older automotive ECU. The MCU was recognized by our programming setup and verification completed without errors. The repaired board now starts and communicates normally.

  • RS48***ieldTech
    Sep 16, 2026

    Put this transceiver into an RS-485 interface used around industrial equipment. Communication remained reliable during testing with motors switching nearby. Good result for the replacement board.

  • Logi***b_Chris
    Sep 8, 2026

    Purchased for a Cyclone III development project. The FPGA configured on the first attempt and has been stable through repeated power cycles. No problems with the I/O we are using.

  • Circ***FixerTom
    Sep 2, 2026

    Used this rectifier in a high-current power supply repair. Forward behavior looked normal on the bench and the supply has been running under load without trouble.

  • Retr***UWorks
    Aug 31, 2026

    Needed the exact ST10F269Z2Q6 for servicing an older control unit. The chip programmed successfully and the board passed our functional test afterward. Much easier than redesigning around a newer MCU.

  • Andr***PCBLab
    Aug 28, 2026

    I needed this ADC for an older data acquisition board. Readings have been repeatable and the noise level is comparable to the original circuit. Happy with the purchase.

  • Leat***O'Keefe
    Aug 20, 2026

    one of my hobbies is skydiving. and when i'm skydiving this works great.

  • Ilen***
    Aug 20, 2026

    This product works considerably well. It secretly improves my basketball by a lot.

  • Indu***ialPower
    Aug 17, 2026

    Installed this IGBT module in a power conversion cabinet. Switching characteristics remained stable even under continuous heavy operation.

  • Nikh***ech
    Aug 13, 2026

    Great low-power MCU for portable equipment. Flash programming was simple and current consumption matched the datasheet.

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Shipment

Delivery Time

In-stock items can be shipped within 24 hours. Some parts will be arranged for delivery within 1-2 days from the date all items arrive at our warehouse. And Allelco ships order once a day at about 17:00, except Sunday. Once the goods are shipped, the estimated delivery time depends on the shipping methods and Delivery destination. The table below shows are the logistic time for some common countries.

Delivery Cost

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  2. Use our account for the shipment. Refer to the table below for the approximate charges.
(Different time frame / countries / package size has different price.)

Delivery Method

  1. Global Common Shipment by DHL / UPS / FedEx / TNT / EMS / SF we support.
  2. Others more shipping ways, please get in touch with your customer manager.

Common Countries Logistic Time Reference
Region Country Logistic Time(Day)
America United States 5
Brazil 7
Europe Germany 5
United Kingdom 4
Italy 5
Oceania Australia 6
New Zealand 5
Asia India 4
Japan 4
Middle East Israel 6
DHL & FedEx Shipment Charges Reference
Shipment charges(KG) Reference DHL(USD$)
0.00kg-1.00kg USD$30.00 - USD$60.00
1.00kg-2.00kg USD$40.00 - USD$80.00
2.00kg-3.00kg USD$50.00 - USD$100.00
Note:
The above table is for reference only. There may have some data bias for the uncontrollable factors.
Contact us if you have any questions.
  • QC (Quality Warranty)
  • Payment Support
  • Packaging
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QC (Quality Warranty)

Allelco is committed to exceeding customer expectations through customer service excellence, order accuracy, and on-time delivery.
This is achieved through our commitment to the continual improvement of our processes, services, and products.


Strict quality inspection builds a solid foundation for electronic component quality.
  1. Visual inspection
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  3. Standardized full-process testing
  4. Precise control of every parameter
We eliminate defective components and ensure the stable operation of electronic devices through professional quality standards.
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Packaging

Electrostatic Discharge Protection and Handling

All electrostatic-sensitive components are handled in accordance with electrostatic discharge control procedures. The products are hermetically sealed in anti-static safe packaging to prevent electrostatic damage. Appropriate labeling is also applied for identification and traceability. This ensures product integrity during storage, handling and transportation.


ESD

Certifications & Memberships

Third-party certified, strict quality control. Our certification
  • ISO 9001: 2015
  • ISO 13485: 2016
  • ISO 14001: 2015
  • ISO 28000: 2007
  • ISO 45001: 2018
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  • IPC
  • ESD
  • PSMA
0459.250UR Image

0459.250UR

Littelfuse Inc.
32D-0459.250UR

Want a better price? Add to Cart and Submit RFQ now, we'll contact you immediately.

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