MF-FSMF050X-2 Equivalent & Substitute Parts

Part Overview

The MF-FSMF050X-2 is a polymeric PTC resettable fuse manufactured by Bourns Inc., rated for 6V maximum voltage with 500 mA hold current. This surface mount component in 0603 (1608 Metric) package format is designed for overcurrent protection in electronic circuits. The part maintains Active product status with full RoHS3 compliance and cURus/TUV approvals. Substitute parts are identified when electrical ratings, mechanical dimensions, and regulatory certifications align with the original specification, enabling direct replacement in circuit designs without functional compromise.

Substiute Parts

MF-FSMF050X-2

Bourns Inc.In Stock: 6126MF-FSMF050X-2 Datasheet

Current PartRFQ

0603L050YR

Littelfuse Inc.In Stock: 616560603L050YR Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MF-FSMF050X-2 is determined by strict alignment of the following electrical and mechanical parameters:

• Voltage rating: 6V maximum
• Hold current (Ih): 500 mA maximum
• Trip current (It): 1 A
• Maximum current capacity: 40 A
• Time to trip: 100 ms
• Initial resistance (Ri): 100 mOhms minimum
• Operating temperature range: -40°C to 85°C
• Package format: 0603 (1608 Metric), Concave, surface mount
• Regulatory compliance: RoHS3, cURus/TUV certification

The substitute part 0603L050YR from Littelfuse Inc. meets all critical electrical parameters and maintains identical regulatory certifications, enabling direct functional replacement.

Parameter Comparison

Engineering Selection Recommendations

Both the MF-FSMF050X-2 and 0603L050YR maintain Active product status with full regulatory compliance. Selection between these parts is based on availability and supply chain considerations rather than functional differences. The post-trip resistance differential (800 mOhms vs. 680 mOhms) falls within acceptable engineering tolerance for polymeric PTC fuse applications and does not affect circuit protection performance. Both components carry identical cURus and TUV certifications, confirming compliance with international safety standards. Inventory availability and lead time are the primary factors for component selection in production environments.

Frequently Asked Questions (FAQ)

Q: Can 0603L050YR directly replace MF-FSMF050X-2 in existing designs?

A: Yes. Both components share identical electrical ratings (6V, 500 mA hold current, 1 A trip current), identical package format (0603 Concave), and matching regulatory certifications (RoHS3, cURus, TUV). Direct substitution is supported without circuit redesign.

Q: What is the significance of the post-trip resistance difference (800 mOhms vs. 680 mOhms)?

A: Post-trip resistance variation is inherent to polymeric PTC fuse manufacturing. The 680 mOhms specification for 0603L050YR is lower than the 800 mOhms maximum for MF-FSMF050X-2, resulting in reduced power dissipation after trip. This represents an improvement in thermal performance and does not compromise protection function.

Q: Are both parts suitable for the same operating temperature range?

A: Yes. Both components operate across -40°C to 85°C, meeting identical environmental specifications for industrial and commercial applications.

Q: Do both parts require the same PCB footprint?

A: Yes. Both components use 0603 (1608 Metric) package format with concave geometry. PCB layouts and assembly processes remain unchanged during substitution.

Q: What certifications apply to both substitute parts?

A: Both MF-FSMF050X-2 and 0603L050YR carry cURus and TUV approvals, confirming compliance with North American and European safety standards. Both maintain ROHS3 compliance and REACH unaffected status.