Littelfuse 0251.125M Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0251.125M is a 125 mA, 125 V AC/DC board mount axial fuse from the PICO® II 251 series. This component is classified as obsolete, making identification of active equivalent parts essential for ongoing production and maintenance applications. The part features fast-blow response characteristics and is approved by CSA and cURus agencies. Due to its obsolete status, direct substitutes with active product status are available to ensure supply chain continuity.

Substiute Parts

0251.125M

Littelfuse Inc.In Stock: 8440251.125M Datasheet

Current PartRFQ

0251.125MXL

Littelfuse Inc.In Stock: 10320251.125MXL Datasheet

Parametric EquivalentRFQ

0251.125VXL

Littelfuse Inc.In Stock: 8920251.125VXL Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 0251.125M is determined by strict equivalence across the following critical parameters:

• Current Rating: 125 mA (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Fast Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Package / Case: Axial (exact match required)
• Breaking Capacity: 50 A AC, 300 A DC (exact match required)
• Melting I²t: 0.00174 (exact match required)
• DC Cold Resistance: 1.7 Ohms (exact match required)
• Operating Temperature Range: -55°C to 125°C (exact match required)
• Physical Dimensions: 0.110" Dia x 0.280" L (exact match required)
• Approval Agencies: CSA, cURus (exact match required)

The substitute parts 0251.125MXL and 0251.125VXL meet all these criteria and are classified as active products, providing direct functional and mechanical equivalence to the obsolete 0251.125M.

Parameter Comparison

Engineering Selection Recommendations

Both 0251.125MXL and 0251.125VXL are direct functional and mechanical equivalents to the obsolete 0251.125M. Selection between these two active alternatives should be based on the following factors:

RoHS Compliance: Both substitute parts are ROHS3 compliant, whereas the main part is RoHS non-compliant. For applications requiring RoHS compliance, either substitute is suitable.

Product Status: The 0251.125M is obsolete and no longer in active production. The 0251.125MXL and 0251.125VXL are both active products with confirmed inventory availability, ensuring long-term supply chain reliability.

Regulatory Approvals: All three parts carry identical CSA and cURus approvals, confirming equivalent safety and performance certification.

Packaging Consideration: The main part is supplied in standard packaging, while both substitutes are supplied in bulk packaging. Bulk packaging may offer cost advantages for high-volume applications.

Frequently Asked Questions (FAQ)

Q: Can 0251.125MXL and 0251.125VXL be used interchangeably with 0251.125M?

A: Yes. Both substitute parts are parametric equivalents with identical electrical and mechanical specifications, including current rating, voltage rating, response time, breaking capacity, and physical dimensions. They are direct replacements for the obsolete 0251.125M.

Q: What is the difference between 0251.125MXL and 0251.125VXL?

A: Both parts are parametric equivalents with identical electrical and mechanical specifications. The difference lies in their part number designation, which may reflect internal Littelfuse manufacturing or packaging variations. Both are active products with ROHS3 compliance and CSA/cURus approvals.

Q: Why is the main part 0251.125M obsolete?

A: The 0251.125M is classified as obsolete by the manufacturer. The active equivalents 0251.125MXL and 0251.125VXL are recommended for new designs and ongoing production to ensure supply chain continuity.

Q: Are there any compliance differences between the main part and substitutes?

A: Yes. The 0251.125M is RoHS non-compliant, while both 0251.125MXL and 0251.125VXL are ROHS3 compliant. Both substitutes maintain identical CSA and cURus approvals as the main part.

Q: What is the physical compatibility of these fuses?

A: All three parts share identical physical dimensions (0.110" Dia x 0.280" L) and axial package configuration, ensuring direct mechanical compatibility in through-hole board mount applications.

Q: Can these fuses be used in both AC and DC circuits?

A: Yes. All three parts are rated for 125 V AC and 125 V DC operation with identical breaking capacities (50 A AC, 300 A DC) and fast-blow response characteristics.