MF-LR260S Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The MF-LR260S is a polymeric PTC resettable fuse manufactured by Bourns Inc. in the Multifuse® MF-LR series. This component provides overcurrent protection at 15V with a 2.6A hold current rating and is designed for user-defined strap mounting applications. The product is currently obsolete, making equivalent and substitute parts necessary for ongoing system support and new designs requiring similar protection characteristics.

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)	83 mOhms
Operating Temperature	-40°C ~ 85°C
Type	Polymeric
Package / Case	Strap
Size / Dimension	0.866" L x 0.199" W (22.00mm x 5.05mm)
Thickness (Max)	0.039" (1.00mm)
RoHS Status	ROHS3 Compliant
Approval Agency	cURus, TUV

Substitute Part Grouping Explanation

Substitution for the MF-LR260S is determined by strict electrical and mechanical parameter matching within the polymeric PTC resettable fuse category. The critical parameters governing substitutability are:

Voltage rating (15V maximum)
Current hold rating (2.6A maximum)
Current trip rating (5.8A)
Resistance characteristics (initial and post-trip)
Operating temperature range (-40°C ~ 85°C)
Physical form factor (strap mounting)
Regulatory compliance (cURus, TUV, or equivalent certifications)

Substitute parts are classified into two categories:

Direct Equivalents: Parts with identical electrical specifications and active product status, differing only in packaging or manufacturer.

Similar Alternatives: Parts with the same voltage and form factor but different current ratings, suitable only when circuit design permits lower hold current specifications.

Parameter Comparison

Parameter	MF-LR260S (Main)	MF-LR260 (Direct)	LR4-260SF (Direct)	LR4-190F (Similar)
Manufacturer	Bourns Inc.	Bourns Inc.	Littelfuse Inc.	Littelfuse Inc.
Series	Multifuse® MF-LR	Multifuse® MF-LR	PolySwitch® LR4	PolySwitch® LR4
Product Status	Obsolete	Active	Active	Active
Voltage - Max	15V	15V	15V	15V
Current - Hold (Ih) (Max)	2.6 A	2.6 A	2.6 A	1.9 A
Current - Trip (It)	5.8 A	5.8 A	5.8 A	3.9 A
Current - Max	100 A	100 A	100 A	100 A
Time to Trip	5 s	5 s	5 s	5 s
Resistance - Initial (Ri) (Min)	20 mOhms	20 mOhms	20 mOhms	39 mOhms
Resistance - Post Trip (R1) (Max)	83 mOhms	83 mOhms	63 mOhms	102 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Type	Polymeric	Polymeric	Polymeric	Polymeric
Package / Case	Strap	Strap	Strap	Strap
Size / Dimension	0.866" L x 0.199" W (22.00mm x 5.05mm)	0.866" L x 0.199" W (22.00mm x 5.05mm)	0.866" L x 0.205" W (22.00mm x 5.20mm)	0.827" L x 0.205" W (21.00mm x 5.20mm)
Thickness (Max)	0.039" (1.00mm)	0.039" (1.00mm)	0.039" (1.00mm)	0.039" (1.00mm)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	cURus, TUV	cURus, TUV	CSA, TUV, UL	CSA, TUV, UL
Inventory Status	981 Pcs New Original	2300 Pcs New Original	2904 Pcs New Original	2475 Pcs New Original

Engineering Selection Recommendations

MF-LR260 (Bourns Inc.): This is the primary direct equivalent for the obsolete MF-LR260S. It maintains identical electrical specifications, voltage rating, current ratings, and resistance characteristics. The only difference is active product status and bulk packaging. This part is recommended as the first choice for direct replacement in new designs and system support applications.

LR4-260SF (Littelfuse Inc.): This part provides direct electrical equivalence with identical voltage, hold current, and trip current specifications. It is manufactured by Littelfuse under the PolySwitch® LR4 series and carries expanded regulatory approvals (CSA, TUV, UL versus cURus, TUV). The post-trip resistance is lower (63 mOhms maximum versus 83 mOhms), which may provide marginal performance benefits in specific circuit topologies. This part is suitable for applications where Littelfuse component qualification is required or preferred.

LR4-190F (Littelfuse Inc.): This part is classified as a similar alternative due to reduced current ratings (1.9A hold, 3.9A trip versus 2.6A hold, 5.8A trip). It is suitable only for circuit designs where the lower current thresholds are acceptable and provide the required protection margin. This part should not be used as a direct replacement without circuit re-evaluation.

All substitute parts maintain ROHS3 compliance, polymeric construction, strap mounting form factor, and the required operating temperature range.

Frequently Asked Questions (FAQ)

Q: Can MF-LR260 be used as a direct replacement for MF-LR260S?

A: Yes. MF-LR260 is a direct equivalent with identical electrical specifications, voltage rating (15V), current hold rating (2.6A), current trip rating (5.8A), and resistance characteristics. The primary difference is that MF-LR260 is an active product with bulk packaging, whereas MF-LR260S is obsolete with strap packaging.

Q: What is the difference between MF-LR260 and LR4-260SF?

A: Both parts have identical voltage (15V), hold current (2.6A), and trip current (5.8A) specifications. The differences are manufacturer (Bourns versus Littelfuse), series designation (Multifuse® MF-LR versus PolySwitch® LR4), regulatory approvals (cURus/TUV versus CSA/TUV/UL), and post-trip resistance (83 mOhms maximum versus 63 mOhms maximum). Both are suitable for direct substitution in applications where the manufacturer is not specified.

Q: Can LR4-190F replace MF-LR260S?

A: LR4-190F is not a direct replacement. It has a lower hold current rating (1.9A versus 2.6A) and lower trip current rating (3.9A versus 5.8A). This part is suitable only for circuits designed to operate at the lower current thresholds. Use of this part requires circuit re-evaluation to confirm that the reduced current ratings provide adequate protection without nuisance trips.

Q: What are the critical parameters for substitution?

A: The critical parameters are voltage rating (15V), current hold rating (2.6A for direct equivalents), current trip rating (5.8A for direct equivalents), operating temperature range (-40°C ~ 85°C), and strap mounting form factor. Resistance characteristics (initial and post-trip) must also be within specified limits to ensure circuit performance.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. MF-LR260, LR4-260SF, and LR4-190F are all ROHS3 compliant, matching the compliance status of the MF-LR260S.

Q: What packaging options are available?

A: MF-LR260 is supplied in bulk packaging. LR4-260SF and LR4-190F are supplied in bag packaging. The original MF-LR260S used strap packaging. All parts are compatible with standard PCB assembly processes for strap-mounted components.

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