Littelfuse 0255.125M Equivalent & Substitute Parts

Part Overview

The Littelfuse 0255.125M is a 125 mA, 125 V AC/DC board mount axial fuse with fast blow response time, designed for through-hole PCB applications. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and production continuity. The PICO® 255 series fuse requires substitution with active production equivalents that maintain identical electrical and mechanical specifications.

Substiute Parts

0255.125M

Littelfuse Inc.In Stock: 10450255.125M Datasheet

Current PartRFQ

0251.125MXL

Littelfuse Inc.In Stock: 10320251.125MXL Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 0255.125M is determined by strict equivalence across the following electrical and mechanical parameters:

• Current Rating: 125 mA (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (both must be met)
• Response Time: Fast Blow (identical thermal characteristics)
• Mounting Type: Through Hole (PCB assembly compatibility)
• Package / Case: Axial (physical form factor and footprint)
• Breaking Capacity: 50A AC, 300A DC (fault protection capability)

The substitute part 0251.125MXL meets all these criteria while offering active production status and improved compliance characteristics.

Parameter Comparison

Engineering Selection Recommendations

The 0251.125MXL is the manufacturer-recommended substitute for the obsolete 0255.125M. Both components share identical electrical ratings and breaking capacity specifications, ensuring functional equivalence in circuit protection applications.

The 0251.125MXL offers the following advantages:

• Active production status ensures long-term availability and supply chain continuity
• ROHS3 compliance meets current environmental and regulatory requirements
• Defined operating temperature range (-55°C ~ 125°C) provides explicit thermal performance boundaries
• Enhanced certification profile (CSA, cURus) supports broader application acceptance

Physical dimensions differ slightly: the substitute has a marginally larger diameter (0.110" vs. 0.095") while maintaining identical length. PCB layout verification is required to confirm footprint compatibility in existing designs, though axial through-hole mounting remains unchanged.

Frequently Asked Questions (FAQ)

Q: Can the 0251.125MXL be used as a direct replacement for the 0255.125M?

A: Yes. Both components have identical current ratings (125 mA), voltage ratings (125 V AC/DC), response time (Fast Blow), and breaking capacity (50A AC, 300A DC). The primary consideration is the slight increase in component diameter (0.110" vs. 0.095"), which requires verification against PCB layout constraints.

Q: What is the difference between the PICO® 255 and PICO® II 251 series?

A: The PICO® II 251 is the active production successor to the PICO® 255 series. Both series maintain equivalent electrical specifications for the 125 mA, 125 V rating. The PICO® II 251 incorporates improved compliance standards (ROHS3) and defined operating temperature specifications.

Q: Are there any compatibility issues with the axial package change?

A: The axial through-hole package remains consistent between both parts. The dimensional difference (diameter increase from 2.41mm to 2.80mm) must be evaluated against PCB hole sizing and component spacing. Length remains identical at 7.11mm (0.280").

Q: Does the RoHS compliance difference affect substitution?

A: The 0251.125MXL is ROHS3 compliant, while the 0255.125M is RoHS non-compliant. For applications subject to RoHS regulations or customer requirements, the substitute provides enhanced compliance. For legacy systems without RoHS mandates, both components function identically from an electrical standpoint.

Q: What certifications apply to each part?

A: The 0255.125M carries CSA and UL approvals. The 0251.125MXL carries CSA and cURus approvals. Both meet recognized safety standards for board mount fuses in their respective voltage and current classes.