LR4-260F Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The LR4-260F is a polymeric PTC resettable fuse manufactured by Littelfuse Inc. in the PolySwitch® LR4 series. This component is rated for 15V maximum voltage with a 2.6 A hold current and is packaged as a user-defined strap configuration. The part is active in production status and carries full compliance certifications including CSA, TUV, and UL approval. Equivalent and substitute parts are identified based on matching electrical characteristics, mechanical dimensions, and operational parameters that permit direct functional replacement in circuit applications.

Key Parameters

Parameter	Value
Voltage - Max	15V
Current - Hold (Ih) (Max)	2.6 A
Current - Trip (It)	5.8 A
Current - Max	100 A
Time to Trip	5 s
Resistance - Initial (Ri) (Min)	20 mOhms
Resistance - Post Trip (R1) (Max)	63 mOhms
Operating Temperature	-40°C ~ 85°C
Type	Polymeric
Package / Case	Strap
Size / Dimension	0.866" L x 0.205" W (22.00mm x 5.20mm)
Thickness (Max)	0.039" (1.00mm)
RoHS Status	ROHS3 Compliant
Approval Agency	CSA, TUV, UL

Substitute Part Grouping Explanation

Substitute parts for the LR4-260F are classified into two functional categories based on electrical parameter alignment:

Category 1: Direct Electrical Equivalents (Identical Hold Current) Parts matching the 2.6 A hold current specification with 15V maximum voltage rating. These components maintain identical trip current (5.8 A) and time-to-trip characteristics, enabling direct circuit substitution without design modification. This category includes the MF-LR260 (Bourns Inc., Multifuse® series) and the 0ZSC0260FF1E (Bel Fuse Inc., 0ZSC series).

Category 2: Current-Variant Alternatives (Different Hold Current) Parts with alternative hold current ratings (1.2 A to 3.8 A) at the same 15V maximum voltage. These components are suitable for applications where circuit protection requirements differ from the primary 2.6 A specification. This category includes MF-LR190 (1.9 A), MF-S120 (1.2 A), MF-S150 (1.5 A), MF-S175 (1.75 A), and MF-LR380 (3.8 A).

Category 3: Form Factor Variants (Surface Mount) Parts with identical or similar electrical characteristics but different mounting technology. The MF-MSMF050-2 (500 mA, 1812 surface mount) and MF-SM125-2 / MF-SM150-2 (1.25 A / 1.5 A, 2-SMD surface mount) serve applications requiring surface-mount assembly instead of strap configuration.

Key substitution parameters: Voltage rating, hold current (Ih), trip current (It), operating temperature range, and package type.

Parameter Comparison

Part Number	Manufacturer	Series	Voltage - Max	Current - Hold (Ih) (Max)	Current - Trip (It)	Time to Trip	Resistance - Initial (Ri) (Min)	Resistance - Post Trip (R1) (Max)	Operating Temperature	Package / Case	Size / Dimension	RoHS Status
LR4-260F	Littelfuse Inc.	PolySwitch® LR4	15V	2.6 A	5.8 A	5 s	20 mOhms	63 mOhms	-40°C ~ 85°C	Strap	0.866" L x 0.205" W (22.00mm x 5.20mm)	ROHS3 Compliant
0ZSC0260FF1E	Bel Fuse Inc.	0ZSC	20V	2.6 A	5.8 A	5 s	20 mOhms	63 mOhms	-40°C ~ 85°C	Strap	0.866" L x 0.205" W (22.00mm x 5.20mm)	ROHS3 Compliant
MF-LR260	Bourns Inc.	Multifuse® MF-LR	15V	2.6 A	5.8 A	5 s	20 mOhms	83 mOhms	-40°C ~ 85°C	Strap	0.866" L x 0.199" W (22.00mm x 5.05mm)	ROHS3 Compliant
MF-LR190	Bourns Inc.	Multifuse® MF-LR	15V	1.9 A	3.9 A	5 s	39 mOhms	102 mOhms	-40°C ~ 85°C	Strap	0.827" L x 0.199" W (21.00mm x 5.05mm)	ROHS3 Compliant
MF-LR380	Bourns Inc.	Multifuse® MF-LR	15V	3.8 A	8.3 A	5 s	13 mOhms	37 mOhms	-40°C ~ 85°C	Strap	0.984" L x 0.283" W (25.00mm x 7.20mm)	ROHS3 Compliant
MF-MSMF050-2	Bourns Inc.	Multifuse® MF-MSMF	15V	500 mA	1 A	150 ms	150 mOhms	1 Ohms	-40°C ~ 85°C	1812 (4532 Metric), Concave	0.179" L x 0.128" W (4.55mm x 3.24mm)	ROHS3 Compliant
MF-S120	Bourns Inc.	Multifuse® MF-S	15V	1.2 A	2.7 A	5 s	85 mOhms	220 mOhms	-40°C ~ 85°C	Strap	0.827" L x 0.199" W (21.00mm x 5.05mm)	ROHS3 Compliant
MF-S150	Bourns Inc.	Multifuse® MF-S	15V	1.5 A	3 A	5 s	50 mOhms	113 mOhms	-40°C ~ 85°C	Strap	0.880" L x 0.417" W (22.35mm x 10.60mm)	ROHS3 Compliant
MF-S175	Bourns Inc.	Multifuse® MF-S	15V	1.75 A	3.8 A	4 s	50 mOhms	120 mOhms	-40°C ~ 85°C	Strap	0.827" L x 0.199" W (21.00mm x 5.05mm)	ROHS3 Compliant
MF-SM125-2	Bourns Inc.	Multifuse® MF-SM	15V	1.25 A	2.5 A	2 s	70 mOhms	250 mOhms	-40°C ~ 85°C	2-SMD	0.287" L x 0.214" W (7.31mm x 5.44mm)	ROHS3 Compliant
MF-SM150-2	Bourns Inc.	Multifuse® MF-SM	15V	1.5 A	3 A	5 s	60 mOhms	250 mOhms	-40°C ~ 85°C	2-SMD	0.344" L x 0.264" W (8.75mm x 6.71mm)	ROHS3 Compliant

Engineering Selection Recommendations

Direct Replacement (No Design Change Required)

The MF-LR260 (Bourns Inc., Multifuse® MF-LR series) provides the closest functional equivalent to the LR4-260F. Both components share identical electrical specifications: 15V maximum voltage, 2.6 A hold current, 5.8 A trip current, and 5 s time-to-trip. Mechanical dimensions are nearly identical (22.00mm length, 5.05mm vs. 5.20mm width). Both carry ROHS3 compliance and cURus/TUV certifications. Post-trip resistance differs slightly (83 mOhms vs. 63 mOhms maximum), which remains within acceptable tolerance for most circuit applications.

The 0ZSC0260FF1E (Bel Fuse Inc., 0ZSC series) offers identical electrical performance with one exception: maximum voltage rating is 20V instead of 15V. This higher voltage rating provides additional design margin in 15V applications. Mechanical dimensions and electrical trip characteristics match the LR4-260F exactly. Certifications include cURus and TUV approval.

Voltage-Rated Alternative

The 0ZSC0260FF1E is suitable for applications where higher voltage margin is beneficial, provided circuit design accommodates the 20V rating without adverse effects.

Current-Variant Selection

Alternative hold current ratings (MF-LR190, MF-S120, MF-S150, MF-S175, MF-LR380) are applicable only when circuit protection requirements differ from the 2.6 A specification. Selection must be based on actual circuit current requirements and fault protection thresholds. All current-variant parts maintain 15V maximum voltage and -40°C to 85°C operating temperature range.

Surface-Mount Alternatives

The MF-MSMF050-2, MF-SM125-2, and MF-SM150-2 are suitable only for applications requiring surface-mount assembly. These parts are not mechanically compatible with strap-based circuit designs. Selection among surface-mount variants depends on required hold current rating and assembly process compatibility.

Frequently Asked Questions (FAQ)

Q: Can the MF-LR260 directly replace the LR4-260F without circuit modification?

A: Yes. The MF-LR260 shares identical voltage rating (15V), hold current (2.6 A), trip current (5.8 A), and time-to-trip (5 s) specifications. Mechanical dimensions are compatible with strap-based mounting. Post-trip resistance tolerance differs slightly but remains functionally equivalent for standard circuit applications.

Q: What is the difference between the LR4-260F and the 0ZSC0260FF1E?

A: Both components have identical electrical performance at 2.6 A hold current and 5.8 A trip current. The primary difference is maximum voltage rating: LR4-260F is rated 15V, while 0ZSC0260FF1E is rated 20V. The higher voltage rating of the 0ZSC0260FF1E provides additional design margin in 15V applications. Both are ROHS3 compliant and carry industry certifications.

Q: Can I use MF-LR190 (1.9 A) in place of LR4-260F (2.6 A)?

A: Only if circuit protection requirements permit a lower hold current threshold. The MF-LR190 will trip at 3.9 A compared to the LR4-260F trip point of 5.8 A. This part is suitable for applications requiring more sensitive overcurrent protection. Direct substitution without circuit analysis is not recommended.

Q: Are surface-mount alternatives (MF-MSMF050-2, MF-SM125-2, MF-SM150-2) compatible with strap-based designs?

A: No. Surface-mount parts require different PCB layout, assembly process, and mounting technology. These alternatives are applicable only to new designs or redesigns that accommodate surface-mount assembly. Mechanical and electrical characteristics differ significantly from strap configurations.

Q: What certifications apply to all substitute parts listed?

A: All substitute parts carry ROHS3 compliance. Approval agencies vary by manufacturer: Littelfuse LR4-260F includes CSA, TUV, and UL; Bel Fuse 0ZSC0260FF1E includes cURus and TUV; Bourns Multifuse® series parts include cURus and TUV. Verify specific certification requirements for your application before final part selection.

Q: Can I use MF-LR380 (3.8 A) for higher current protection?

A: Only if circuit design requires a higher hold current threshold. The MF-LR380 will not trip until 8.3 A compared to the LR4-260F trip point of 5.8 A. This part provides less sensitive protection and is suitable only for applications with higher current requirements. Circuit analysis is required before substitution.

Q: What is the difference between MF-S series and MF-LR series parts?

A: Both are Bourns Multifuse® strap-based polymeric PTC resettable fuses with 15V maximum voltage and -40°C to 85°C operating temperature. The primary differences are hold current ratings and mechanical dimensions. MF-S series parts (MF-S120, MF-S150, MF-S175) offer lower current ratings with different resistance characteristics. MF-LR series parts (MF-LR190, MF-LR260, MF-LR380) provide alternative current ratings within the same mechanical family. Selection depends on specific circuit protection requirements.

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