MF-R400-2-99 Equivalent & Substitute Parts

Part Overview

The MF-R400-2-99 is a polymeric PTC resettable fuse manufactured by Bourns Inc., rated for 30V maximum voltage and 4A hold current. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. The part operates across a temperature range of -40°C to 85°C and is ROHS3 compliant with cURus and TUV approval.

Key Parameters

Parameter	Value
Voltage - Max	30V
Current - Hold (Ih) (Max)	4 A
Current - Trip (It)	8 A
Current - Max	40 A
Time to Trip	12.7 s
Resistance - Initial (Ri) (Min)	10 mOhms
Resistance - Post Trip (R1) (Max)	50 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole
Package / Case	Radial, Disc
Type	Polymeric
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the MF-R400-2-99 is determined by strict parametric matching across the following critical criteria:

Voltage - Max: 30V
Current - Hold (Ih) (Max): 4 A
Current - Trip (It): 8 A
Time to Trip: 12.7 s
Resistance - Initial (Ri) (Min): 10 mOhms
Resistance - Post Trip (R1) (Max): 50 mOhms
Operating Temperature: -40°C ~ 85°C
Mounting Type: Through Hole
Package / Case: Radial, Disc
Type: Polymeric

Substitute parts are grouped into three categories based on their relationship to the main part:

Parametric Equivalents (Bourns Inc.): Parts that match all critical electrical and mechanical parameters with identical or compatible packaging. These include MF-R400, MF-R400-2, and MF-R400-2-14, all from the Multifuse® MF-R series.

Direct Equivalents (Cross-Manufacturer): Parts from alternative manufacturers (Eaton, Littelfuse, SCHURTER) that meet identical electrical specifications and mechanical dimensions. These include PTR030V0400-TR, PTR030V0400-TR1, RUEF400-2, RUEF400K-2, and PFRA.400.2.

Parameter Comparison

Part Number	Manufacturer	Voltage - Max	Current - Hold (Ih)	Current - Trip (It)	Current - Max	Time to Trip	Ri (Min)	R1 (Max)	Operating Temp	Packaging	Product Status
MF-R400-2-99	Bourns Inc.	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Tape & Reel	Obsolete
MF-R400	Bourns Inc.	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Bulk	Active
MF-R400-2	Bourns Inc.	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Cut Tape	Active
MF-R400-2-14	Bourns Inc.	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Cut Tape	Active
PTR030V0400-TR	Eaton - Electronics Division	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Cut Tape	Active
PTR030V0400-TR1	Eaton - Electronics Division	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Tape & Reel	Active
RUEF400-2	Littelfuse	30V	4 A	8 A	100 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Cut Tape	Active
RUEF400K-2	Littelfuse Inc.	30V	4 A	8 A	100 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Cut Tape	Active
PFRA.400.2	SCHURTER Inc.	30V	4 A	8 A	40 A	12.7 s	10 mOhms	50 mOhms	-40°C ~ 85°C	Cut Tape	Active

Engineering Selection Recommendations

Primary Recommendation: MF-R400-2 (Bourns Inc.) is the direct parametric equivalent with active product status. This part maintains identical electrical specifications and mechanical form factor while offering superior inventory availability (68,735 units in stock). ROHS3 compliance and cURus/TUV approvals are maintained.

Secondary Recommendation: PTR030V0400-TR1 (Eaton - Electronics Division) provides cross-manufacturer equivalence with active status and Tape & Reel packaging matching the original MF-R400-2-99 format. Approvals include cURus and TUV certification.

Alternative Recommendation: RUEF400-2 or RUEF400K-2 (Littelfuse PolySwitch® series) meet all critical electrical parameters with enhanced current handling capability (100A maximum vs. 40A). Both parts carry expanded certifications including CQC, CSA, TUV, and UL. These are suitable for applications requiring additional safety margin.

Packaging Consideration: For automated assembly requiring Tape & Reel format, PTR030V0400-TR1 is the preferred substitute. For manual or bulk assembly, MF-R400-2 in Cut Tape packaging offers maximum availability.

Frequently Asked Questions (FAQ)

Q: Can MF-R400-2 directly replace MF-R400-2-99?

A: Yes. MF-R400-2 is a parametric equivalent with identical electrical specifications (30V, 4A hold current, 8A trip current, 12.7s trip time) and mechanical dimensions. The primary difference is product status (active vs. obsolete) and packaging format (Cut Tape vs. Tape & Reel).

Q: What is the difference between Bourns MF-R400 variants and Littelfuse RUEF400 series?

A: All parts meet the core electrical requirements (30V, 4A hold, 8A trip). The RUEF400-2 and RUEF400K-2 feature higher maximum current ratings (100A vs. 40A) and broader certification coverage (CQC, CSA, TUV, UL vs. cURus, TUV). Selection depends on application requirements and certification mandates.

Q: Are there mechanical compatibility concerns between manufacturers?

A: Mechanical dimensions vary slightly between manufacturers. Bourns MF-R400-2-99 and PFRA.400.2 share identical lead spacing (0.201", 5.10mm) and height (0.976", 24.80mm). Eaton PTR030V0400-TR1 and Littelfuse RUEF400-2 have slightly different dimensions (lead spacing 0.197"-0.199", height 0.760"-0.969"). Verify PCB footprint compatibility before substitution.

Q: Which substitute offers the best inventory availability?

A: MF-R400-2 (Bourns Inc.) provides the highest inventory level at 68,735 units in stock, followed by RUEF400-2 (Littelfuse) at 18,032 units.

Q: Are all substitutes ROHS3 compliant?

A: Yes. All listed substitute parts carry ROHS3 compliance certification.

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