MF-R050-2-99 Equivalent & Substitute Parts

Part Overview

The Bourns MF-R050-2-99 is a polymeric PTC resettable fuse rated for 60V maximum voltage with 500 mA hold current. This component is classified as obsolete, necessitating identification of active equivalent alternatives for new designs and production continuity. The part belongs to the Multifuse® MF-R series and is designed for through-hole radial mounting in disc configuration. Equivalent and substitute parts maintain the same electrical performance characteristics while offering active product status and improved availability.

Key Parameters

Parameter	Value
Voltage - Max	60V
Current - Hold (Ih) (Max)	500 mA
Current - Trip (It)	1 A
Current - Max	40 A
Time to Trip	4 s
Resistance - Initial (Ri) (Min)	410 mOhms
Resistance - Post Trip (R1) (Max)	1.17 Ohms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Size / Dimension	0.311" Dia x 0.122" T (7.90mm x 3.10mm)
Lead Spacing	0.201" (5.10mm)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution logic for the MF-R050-2-99 is based on strict electrical and mechanical parameter matching. Parametric equivalents maintain identical specifications across all critical parameters: 60V maximum voltage, 500 mA hold current, 1 A trip current, 4 second trip time, 410 mOhms initial resistance, and 1.17 Ohms maximum post-trip resistance. All parametric equivalents share the same through-hole radial disc package configuration with 0.311" diameter, 0.122" thickness, and 0.201" lead spacing.

Parametric equivalents from Bourns include MF-R050-2, MF-R050-2-17, MF-R050-AP, and MF-R050-AP-17, which differ only in packaging format (Cut Tape versus Tape & Reel) and product status (all active). The MF-RX050/72 series variants (MF-RX050/72-2-17 and MF-RX050/72-AP) are parametric equivalents with identical electrical characteristics but rated for 72V maximum voltage, suitable for applications requiring higher voltage margin.

The Littelfuse RXEF017-AP is classified as a similar part due to differing hold current (170 mA versus 500 mA) and trip current (340 mA versus 1 A), making it suitable only for lower-current applications. The SCHURTER PFRA.050.2 is a parametric equivalent with identical electrical specifications and mechanical dimensions, offering cross-manufacturer compatibility.

Parameter Comparison

Part Number	Manufacturer	Voltage - Max	Current - Hold (Ih)	Current - Trip (It)	Resistance - Initial (Ri)	Resistance - Post Trip (R1)	Time to Trip	Packaging	Product Status
MF-R050-2-99	Bourns Inc.	60V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Radial, Disc	Obsolete
MF-R050-2	Bourns Inc.	60V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Cut Tape (CT)	Active
MF-R050-2-17	Bourns Inc.	60V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Tape & Reel (TR)	Active
MF-R050-AP	Bourns Inc.	60V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Cut Tape (CT)	Active
MF-R050-AP-17	Bourns Inc.	60V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Tape & Reel (TR)	Active
MF-RX050/72-2-17	Bourns Inc.	72V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Tape & Reel (TR)	Active
MF-RX050/72-AP	Bourns Inc.	72V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Cut Tape (CT)	Active
PFRA.050.2	SCHURTER Inc.	60V	500 mA	1 A	410 mOhms	1.17 Ohms	4 s	Cut Tape (CT)	Active
RXEF017-AP	Littelfuse	60V	170 mA	340 mA	3.3 Ohms	8 Ohms	3 s	Cut Tape (CT)	Active

Engineering Selection Recommendations

For direct replacement of the obsolete MF-R050-2-99, select from the active Bourns parametric equivalents: MF-R050-2, MF-R050-2-17, MF-R050-AP, or MF-R050-AP-17. These parts maintain 100% electrical and mechanical compatibility with identical 60V voltage rating, 500 mA hold current, and physical dimensions. Packaging selection depends on procurement requirements: Cut Tape (CT) for manual assembly or Tape & Reel (TR) for automated production. All active Bourns alternatives carry ROHS3 compliance and cURus/TUV certifications matching the original part.

The SCHURTER PFRA.050.2 provides cross-manufacturer compatibility with identical electrical specifications and mechanical form factor, suitable for applications requiring supply chain diversification. This part is ROHS3 compliant and cURus/TUV certified.

The Bourns MF-RX050/72 series (MF-RX050/72-2-17 and MF-RX050/72-AP) are suitable for applications where 72V maximum voltage rating is required, maintaining all other electrical characteristics. These parts carry AEC-Q200 automotive qualification and expanded certification coverage (cUL, cURus, TUV, UL).

The Littelfuse RXEF017-AP is not a direct replacement due to significantly lower hold current (170 mA versus 500 mA) and trip current (340 mA versus 1 A). This part is suitable only for applications with lower current protection requirements.

Frequently Asked Questions (FAQ)

Q: Can MF-R050-2 directly replace MF-R050-2-99? A: Yes. MF-R050-2 is a parametric equivalent with identical electrical specifications (60V, 500 mA hold current, 1 A trip current) and mechanical dimensions. The difference is product status (active versus obsolete) and packaging format (Cut Tape versus unspecified original packaging).

Q: What is the difference between MF-R050-2 and MF-R050-2-17? A: Both parts are parametric equivalents with identical electrical and mechanical specifications. The difference is packaging: MF-R050-2 is supplied in Cut Tape (CT) format, while MF-R050-2-17 is supplied in Tape & Reel (TR) format. MF-R050-2-17 includes AEC-Q200 automotive qualification and expanded certifications (cUL, cURus, TUV, UL).

Q: Can I use MF-RX050/72-AP instead of MF-R050-2-99? A: Yes, with consideration for voltage rating. MF-RX050/72-AP maintains identical electrical performance (500 mA hold current, 1 A trip current, 4 second trip time) but is rated for 72V maximum voltage instead of 60V. This higher voltage rating is suitable for applications operating at or below 60V and provides additional voltage margin.

Q: Is RXEF017-AP compatible with MF-R050-2-99? A: No. RXEF017-AP has significantly different electrical specifications: 170 mA hold current (versus 500 mA), 340 mA trip current (versus 1 A), 3.3 Ohms initial resistance (versus 410 mOhms), and 3 second trip time (versus 4 seconds). This part is suitable only for lower-current applications and is not a direct substitute.

Q: What certifications should I verify for replacement parts? A: All recommended parametric equivalents carry ROHS3 compliance. For direct replacement, verify cURus and TUV certifications match the original part. The MF-R050-2-17 and MF-R050-AP-17 variants include additional cUL and UL certifications plus AEC-Q200 automotive qualification.

Q: Can PFRA.050.2 from SCHURTER replace the Bourns MF-R050-2-99? A: Yes. PFRA.050.2 is a parametric equivalent with identical electrical specifications (60V, 500 mA hold current, 1 A trip current) and mechanical dimensions (0.311" diameter, 0.201" lead spacing). This part provides cross-manufacturer compatibility and is ROHS3 compliant with cURus/TUV certifications.

Q: What is the lead spacing for all these parts? A: All parametric equivalents maintain 0.201" (5.10mm) lead spacing, ensuring mechanical compatibility with existing PCB layouts designed for MF-R050-2-99.

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