Equivalent & Substitute Parts for MF-S175S

Part Overview

The MF-S175S is a polymeric PTC resettable fuse manufactured by Bourns Inc. in the Multifuse® MF-S series. This component is rated for 15V maximum voltage with a 1.75A hold current and 3.8A trip current, designed for strap mounting applications. The part is currently obsolete, making identification of equivalent and substitute components essential for ongoing system support and new design implementations.

Substiute Parts

MF-S175S

Bourns Inc.In Stock: 1271MF-S175S Datasheet

Current PartRFQ

MF-S175

Bourns Inc.In Stock: 7154MF-S175 Datasheet

DirectRFQ

LR4-190F

Littelfuse Inc.In Stock: 2515LR4-190F Datasheet

SimilarRFQ

LR4-260SF

Littelfuse Inc.In Stock: 2958LR4-260SF Datasheet

SimilarRFQ

SRP175SF

Littelfuse Inc.In Stock: 19277SRP175SF Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MF-S175S is determined by the following critical parameters:

• Voltage rating (15V maximum)
• Current hold rating (1.75A nominal)
• Current trip rating (3.8A nominal)
• Package type (Strap mounting)
• Operating temperature range (-40°C ~ 85°C)
• Polymeric PTC resettable fuse technology
• Regulatory compliance (RoHS3, cURus/TUV certification)

Substitute parts are grouped into two categories:

Direct Equivalent: MF-S175 (Bourns Inc.) - Identical electrical specifications and dimensions, differing only in product status (Active vs. Obsolete) and packaging format (Bulk vs. Strap designation).

Similar Alternatives: LR4-190F, LR4-260SF, and SRP175SF (Littelfuse Inc.) - These parts maintain the 15V voltage rating and strap package type but vary in hold current, trip current, and resistance characteristics. Selection depends on circuit tolerance for these parameter variations.

Parameter Comparison

Engineering Selection Recommendations

MF-S175 (Direct Equivalent): This is the primary substitute for MF-S175S. It maintains identical electrical and mechanical specifications while offering active product status and improved availability. The only distinction is packaging format. This part is recommended for direct replacement in existing designs.

SRP175SF (Littelfuse PolySwitch® SRP): This part matches the MF-S175S in hold current (1.75A), trip current (3.8A), and resistance characteristics. It is manufactured by Littelfuse Inc. with CSA, TUV, and UL certifications, providing broader regulatory approval than the original part. Dimensional variation (0.866" L vs. 0.827" L) requires mechanical verification for board layout compatibility.

LR4-190F (Littelfuse PolySwitch® LR4): This part operates at 1.9A hold current and 3.9A trip current, representing a 8.6% increase in hold current and 2.6% increase in trip current compared to MF-S175S. Lower initial resistance (39 mOhms vs. 50 mOhms) and lower post-trip resistance (102 mOhms vs. 120 mOhms) result in reduced voltage drop characteristics. This part is suitable only when circuit design tolerates higher trip thresholds.

LR4-260SF (Littelfuse PolySwitch® LR4): This part operates at 2.6A hold current and 5.8A trip current, representing a 48.6% increase in hold current and 52.6% increase in trip current. Significantly lower resistance values (20 mOhms initial, 63 mOhms post-trip) provide minimal voltage drop but fundamentally alter circuit protection behavior. This part is not recommended as a substitute for MF-S175S due to substantial parameter deviation.

Frequently Asked Questions (FAQ)

Q: Can MF-S175 be used as a direct replacement for MF-S175S?

A: Yes. MF-S175 is electrically and mechanically identical to MF-S175S. The primary difference is product status (Active vs. Obsolete) and packaging designation. MF-S175 is the recommended direct substitute.

Q: What is the difference between Bourns Multifuse® and Littelfuse PolySwitch® parts?

A: Both are polymeric PTC resettable fuses with identical operating principles. The primary differences are manufacturer, regulatory certifications, and specific electrical characteristics. Littelfuse parts in this comparison offer broader certification coverage (CSA, TUV, UL vs. cURus, TUV).

Q: Can LR4-190F be used instead of MF-S175S?

A: LR4-190F can be used only if circuit design accommodates a 1.9A hold current and 3.9A trip current. The 8.6% increase in hold current and 2.6% increase in trip current may affect circuit protection timing. Verification of circuit tolerance is required before substitution.

Q: Why is LR4-260SF not recommended as a substitute?

A: LR4-260SF operates at 2.6A hold current and 5.8A trip current, representing a 48.6% increase in hold current and 52.6% increase in trip current compared to MF-S175S. This substantial deviation fundamentally alters circuit protection behavior and is not suitable for direct substitution.

Q: Are there mechanical compatibility concerns with Littelfuse alternatives?

A: Yes. SRP175SF has a length of 0.866" compared to MF-S175S at 0.827", and LR4-260SF measures 0.866" L x 0.205" W. Board layout and mechanical mounting must be verified before substitution. LR4-190F dimensions (0.827" L x 0.205" W) present minimal width variation requiring verification of strap contact spacing.

Q: What certifications apply to each substitute part?

A: MF-S175 carries cURus and TUV certifications. SRP175SF, LR4-190F, and LR4-260SF carry CSA, TUV, and UL certifications. System compliance requirements determine which certifications are necessary for your application.

Q: Is RoHS3 compliance maintained across all substitute parts?

A: Yes. All substitute parts listed (MF-S175, SRP175SF, LR4-190F, LR4-260SF) are ROHS3 Compliant.