MF-RX185-2 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The Bourns MF-RX185-2 is a polymeric PTC resettable fuse rated for 60V at 1.85A hold current, designed for through-hole radial mounting in disc configuration. This component is classified as obsolete, making identification of equivalent and substitute parts essential for ongoing design support and procurement continuity. Active alternatives with identical or enhanced electrical characteristics are available from multiple manufacturers.

Key Parameters

Parameter	Value
Voltage - Max	60V
Current - Hold (Ih) (Max)	1.85 A
Current - Trip (It)	3.7 A
Current - Max	40 A
Time to Trip	12.6 s
Resistance - Initial (Ri) (Min)	80 mOhms
Resistance - Post Trip (R1) (Max)	190 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Lead Spacing	0.201" (5.10mm)
Approval Agency	cURus, TUV
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the MF-RX185-2 is determined by the following critical parameters:

Electrical Compatibility Parameters:

Current - Hold (Ih) (Max): Must equal 1.85 A
Current - Trip (It): Must equal 3.7 A
Resistance - Initial (Ri) (Min): Must equal 80 mOhms
Resistance - Post Trip (R1) (Max): Must equal 190 mOhms
Time to Trip: Must equal 12.6 s
Operating Temperature: Must support -40°C ~ 85°C range

Mechanical Compatibility Parameters:

Mounting Type: Must be Through Hole
Package / Case: Must be Radial, Disc
Lead Spacing: Must equal 0.201" (5.10mm)

Regulatory Compliance Parameters:

Approval Agency: Must include cURus and/or TUV
RoHS Status: Must be ROHS3 Compliant

Voltage Consideration: Substitutes with voltage ratings equal to or greater than 60V are acceptable, as higher voltage ratings provide backward compatibility in lower voltage applications.

Parameter Comparison

Parameter	MF-RX185-2 (Main)	MF-RX185/72-0	MF-RX185/72-2	60R185XF	0ZRC0185FF2B
Manufacturer	Bourns Inc.	Bourns Inc.	Bourns Inc.	Littelfuse	Bel Fuse Inc.
Voltage - Max	60V	72V	72V	60V	90V
Current - Hold (Ih) (Max)	1.85 A	1.85 A	1.85 A	1.85 A	1.85 A
Current - Trip (It)	3.7 A	3.7 A	3.7 A	3.7 A	3.7 A
Current - Max	40 A	40 A	40 A	40 A	40 A
Time to Trip	12.6 s	12.6 s	12.6 s	12.6 s	12.6 s
Resistance - Initial (Ri) (Min)	80 mOhms	80 mOhms	80 mOhms	80 mOhms	80 mOhms
Resistance - Post Trip (R1) (Max)	190 mOhms	190 mOhms	190 mOhms	190 mOhms	190 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc	Radial, Disc
Lead Spacing	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)	0.201" (5.10mm)
Approval Agency	cURus, TUV	cURus, TUV	cURus, TUV	cURus, TUV	cURus, TUV
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active	Active
Packaging	-	Bulk	Cut Tape (CT)	Bulk	Tape & Reel (TR)

Engineering Selection Recommendations

All four substitute parts meet the electrical and mechanical compatibility requirements for the obsolete MF-RX185-2. Selection should be based on the following criteria:

Bourns MF-RX185/72-0 and MF-RX185/72-2: Both are active Bourns products with 72V voltage rating, providing enhanced overvoltage margin. These maintain design continuity within the Multifuse MF-RX series. MF-RX185/72-2 is available in Cut Tape packaging with higher inventory (16,643 pcs), while MF-RX185/72-0 is available in Bulk packaging (4,200 pcs).

Littelfuse 60R185XF: This part maintains the original 60V voltage specification and is an active product in the POLY-FUSE 60R series. It provides direct electrical equivalence with identical hold current, trip current, and resistance characteristics. Available in Bulk packaging with 4,463 pcs in stock.

Bel Fuse Inc. 0ZRC0185FF2B: This part offers the highest voltage rating at 90V, providing maximum overvoltage protection margin. It includes AEC-Q200 automotive qualification and is available in Tape & Reel packaging (813 pcs). Moisture Sensitivity Level is Not Applicable, indicating enhanced environmental robustness.

All substitutes carry cURus and TUV approvals and maintain ROHS3 compliance.

Frequently Asked Questions (FAQ)

Q: Can MF-RX185/72-0 and MF-RX185/72-2 be used interchangeably with MF-RX185-2? A: Yes. Both parts are electrically and mechanically identical to the main part, with the exception of higher voltage rating (72V vs. 60V). The higher voltage rating does not affect performance in 60V applications. The difference between these two Bourns parts is packaging: MF-RX185/72-0 is Bulk, while MF-RX185/72-2 is Cut Tape.

Q: What is the difference between the Littelfuse 60R185XF and the Bourns substitutes? A: The Littelfuse 60R185XF maintains the original 60V voltage specification and is from a different manufacturer (Littelfuse POLY-FUSE series vs. Bourns Multifuse series). All electrical parameters, mechanical dimensions, and lead spacing are identical. Physical dimensions show minor variation: 0.660" Dia vs. 0.701" L for the main part, but lead spacing remains 0.201" (5.10mm).

Q: Is the Bel Fuse 0ZRC0185FF2B suitable for direct replacement? A: Yes. The 0ZRC0185FF2B meets all electrical and mechanical compatibility requirements. Its 90V rating provides additional overvoltage margin. This part includes AEC-Q200 automotive qualification and Tape & Reel packaging, making it suitable for automated assembly processes.

Q: What packaging options are available for these substitutes? A: MF-RX185/72-0 is available in Bulk; MF-RX185/72-2 is available in Cut Tape (CT); 60R185XF is available in Bulk; 0ZRC0185FF2B is available in Tape & Reel (TR). Selection depends on assembly process requirements and procurement volume.

Q: Are all substitutes RoHS3 compliant? A: Yes. All four substitute parts are ROHS3 Compliant and carry cURus and TUV approvals, meeting current regulatory requirements.

Q: Can I use a higher voltage rated part in a 60V circuit? A: Yes. Parts rated for 72V or 90V can be used in 60V applications without performance degradation. The higher voltage rating indicates the component can withstand higher electrical stress, making it suitable for lower voltage environments.

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