LR4-190LF Equivalent & Substitute Parts

Part Overview

The LR4-190LF is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 15V maximum voltage with a 1.9A hold current. This component is classified as obsolete, making identification of equivalent substitute parts essential for ongoing system support and component procurement. The LR4-190LF belongs to the PolySwitch® LR4 series and is designed for applications requiring automatic overcurrent protection with resettable functionality.

Key Parameters

Parameter	Value
Voltage - Max	15V
Current - Hold (Ih) (Max)	1.9 A
Current - Trip (It)	3.9 A
Current - Max	100 A
Time to Trip	5 s
Resistance - Initial (Ri) (Min)	39 mOhms
Resistance - Post Trip (R1) (Max)	102 mOhms
Operating Temperature	-40°C ~ 85°C
Type	Polymeric
Package / Case	Strap
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the LR4-190LF is determined by electrical parameter equivalence across the polymeric PTC resettable fuse category. The critical parameters governing substitution are:

Voltage - Max: 15V
Current - Hold (Ih) (Max): 1.9 A
Current - Trip (It): 3.9 A
Resistance - Initial (Ri) (Min): 39 mOhms
Resistance - Post Trip (R1) (Max): 102 mOhms
Operating Temperature: -40°C ~ 85°C
Package / Case: Strap
Type: Polymeric

The MF-LR190 from Bourns Inc. meets all specified electrical and mechanical parameters, making it a direct equivalent substitute for the obsolete LR4-190LF.

Parameter Comparison

Parameter	LR4-190LF (Littelfuse)	MF-LR190 (Bourns)
Voltage - Max	15V	15V
Current - Hold (Ih) (Max)	1.9 A	1.9 A
Current - Trip (It)	3.9 A	3.9 A
Current - Max	100 A	100 A
Time to Trip	5 s	5 s
Resistance - Initial (Ri) (Min)	39 mOhms	39 mOhms
Resistance - Post Trip (R1) (Max)	102 mOhms	102 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C
Type	Polymeric	Polymeric
Package / Case	Strap	Strap
RoHS Status	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

The MF-LR190 is the direct substitute for the obsolete LR4-190LF. Both components are ROHS3 compliant and carry equivalent regulatory approvals (CSA, TUV, UL for the original; cURus, TUV for the substitute). The MF-LR190 maintains active product status with Bourns Inc., ensuring ongoing availability and supply chain continuity. All electrical parameters, thermal operating range, and mechanical package specifications are identical between the two components.

Frequently Asked Questions (FAQ)

Q: Can the MF-LR190 be used as a direct replacement for the LR4-190LF?

A: Yes. The MF-LR190 is electrically and mechanically equivalent to the LR4-190LF across all specified parameters, including voltage rating, current ratings, resistance characteristics, and operating temperature range.

Q: Are there dimensional differences between the LR4-190LF and MF-LR190?

A: Both components use strap packaging. The LR4-190LF measures 1.161" L x 0.205" W (29.50mm x 5.20mm), while the MF-LR190 measures 0.827" L x 0.199" W (21.00mm x 5.05mm). Physical dimensions differ, but electrical performance is identical.

Q: What is the product status difference between these parts?

A: The LR4-190LF is obsolete, while the MF-LR190 is active. This makes the MF-LR190 the recommended choice for new designs and ongoing procurement.

Q: Are both parts RoHS compliant?

A: Yes. Both the LR4-190LF and MF-LR190 are ROHS3 compliant.

Q: What regulatory approvals apply to the MF-LR190?

A: The MF-LR190 carries cURus and TUV approvals.

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