Littelfuse 37014000000 Board Mount Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 37014000000 is a 4 A, 250 V AC/DC board mount fuse with fast blow response characteristics, designed for through-hole radial mounting in TR5® 370 series applications. This component is currently active in production with 919 pieces in stock. Substitute parts are identified based on matching electrical ratings, mechanical compatibility, and approval agency certifications to ensure functional equivalence in circuit protection applications.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	250 V
Mounting Type	Through Hole
Package / Case	Radial, Can, Vertical
Response Time	Fast Blow
Size / Dimension	0.335" Dia x 0.315" H (8.50mm x 8.00mm)
Breaking Capacity @ Rated Voltage	40 A
Operating Temperature Range	-40°C ~ 85°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the Littelfuse 37014000000 are classified based on the following substitution criteria:

Parametric Equivalent (Direct Electrical Match):

Current Rating: 4 A
Voltage Rating: 250 V AC
Mounting Type: Through Hole
Package / Case: Radial, Can, Vertical
Operating Temperature: -40°C ~ 85°C

Parts meeting all these criteria are considered parametric equivalents. The Littelfuse 37314000000 (TR5® 373 series) qualifies as a parametric equivalent with identical electrical ratings and mechanical form factor.

Direct Manufacturer Alternatives (Functional Equivalents):

Current Rating: 4 A
Voltage Rating: 250 V AC
Mounting Type: Through Hole
Package / Case: Radial, Can, Vertical

The Bel Fuse Inc. MRF 4-BULK meets these core functional requirements with minor dimensional variation (0.329" Dia x 0.303" H vs. 0.335" Dia x 0.315" H) and extended operating temperature range (-55°C ~ 125°C).

Partial Rating Alternatives (Current Derating Required):

The Eaton SR-5-2.5A-BK operates at 2.5 A, representing a 37.5% current reduction from the 4 A rating. This part is listed as a substitute only where circuit design permits lower current protection thresholds.

Manufacturer Recommended Alternatives (Response Time Variation):

The Eaton SR-5-4A-AP and SR-5-4A-BK maintain 4 A, 250 V ratings with slow blow response characteristics, differing from the fast blow response of the primary part. These are suitable where circuit topology requires slower response characteristics.

Parameter Comparison

Parameter	37014000000 (Littelfuse)	37314000000 (Littelfuse)	MRF 4-BULK (Bel Fuse)	SR-5-4A-AP (Eaton)	SR-5-4A-BK (Eaton)	SR-5-2.5A-BK (Eaton)
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Bel Fuse Inc.	Eaton - Electronics Division	Eaton - Electronics Division	Eaton - Electronics Division
Current Rating (Amps)	4 A	4 A	4 A	4 A	4 A	2.5 A
Voltage Rating - AC	250 V	250 V	250 V	250 V	250 V	250 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Slow Blow	Slow Blow	Slow Blow
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical
Size / Dimension	0.335" Dia x 0.315" H (8.50mm x 8.00mm)	0.335" Dia x 0.315" H (8.50mm x 8.00mm)	0.329" Dia x 0.303" H (8.35mm x 7.70mm)	0.335" Dia x 0.319" H (8.50mm x 8.10mm)	0.335" Dia x 0.319" H (8.50mm x 8.10mm)	0.335" Dia x 0.319" H (8.50mm x 8.10mm)
Breaking Capacity @ Rated Voltage	40 A	50 A	40 A	40 A	40 A	35 A
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-55°C ~ 125°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Approval Agency	CCC, cURus, PSE, SEMKO, VDE	CSA, cULus	AEC-Q200, CE, CSA, cULus, PSE, SEMKO, VDE	CCC, cULus, KC-MARK, PSE, SEMKO, VDE	CCC, cULus, KC-MARK, PSE, SEMKO, VDE	CCC, cULus, KC-MARK, PSE, SEMKO, VDE
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Active	Active	Active	Active	Active	Active

Engineering Selection Recommendations

Primary Substitute - Littelfuse 37314000000: This part provides the closest parametric match with identical current and voltage ratings, matching mechanical dimensions, and overlapping approval certifications (CCC, cULus). The TR5® 373 series variant maintains fast blow response and operates within the same temperature range. Selection is appropriate for direct replacement in TR5® series applications.

Extended Temperature Range Alternative - Bel Fuse Inc. MRF 4-BULK: The MRF 4-BULK offers expanded operating temperature capability (-55°C ~ 125°C) compared to the primary part (-40°C ~ 85°C), with comprehensive approval agency coverage including AEC-Q200 automotive qualification. Dimensional variation is minimal (0.006" diameter reduction, 0.012" height reduction). This part is suitable for applications requiring extended temperature performance or automotive compliance.

Response Time Variants - Eaton SR-5-4A-AP and SR-5-4A-BK: Both Eaton parts maintain 4 A, 250 V ratings with identical mechanical form factors but employ slow blow response characteristics. These are applicable only where circuit design specifications explicitly require slow blow fuse behavior. The SR-5-4A-AP is supplied in cut tape packaging; the SR-5-4A-BK is supplied in bulk packaging.

Current Derating Alternative - Eaton SR-5-2.5A-BK: This part operates at 2.5 A, representing a 37.5% reduction in current protection threshold. Selection requires circuit design verification to confirm that lower current protection is acceptable for the intended application.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 37314000000 be used as a direct replacement for the 37014000000?

A: Yes. Both parts share identical 4 A, 250 V ratings, fast blow response, through-hole radial mounting, and mechanical dimensions (0.335" Dia x 0.315" H). The primary difference is the series designation (TR5® 373 vs. TR5® 370) and approval agency coverage. Verification of approval agency requirements for your specific application is recommended.

Q: What is the difference between fast blow and slow blow fuses?

A: Fast blow fuses respond quickly to overcurrent conditions, providing protection against transient surges and short circuits. Slow blow fuses tolerate temporary inrush currents and respond only to sustained overcurrent conditions. The Littelfuse 37014000000 is fast blow; the Eaton SR-5 series parts are slow blow. Selection depends on circuit topology and inrush current characteristics.

Q: Can I use the Eaton SR-5-2.5A-BK in place of the Littelfuse 37014000000?

A: The SR-5-2.5A-BK operates at 2.5 A versus the 4 A rating of the primary part. This represents a 37.5% reduction in current protection threshold. Substitution is only valid if circuit design permits operation at the lower current rating. Electrical verification is required before implementation.

Q: What are the dimensional constraints for board mount fuse substitution?

A: The primary part measures 0.335" Dia x 0.315" H (8.50mm x 8.00mm). All listed substitutes maintain radial, can, vertical package geometry compatible with through-hole mounting. The Bel Fuse MRF 4-BULK exhibits minor dimensional variation (0.329" Dia x 0.303" H / 8.35mm x 7.70mm) and remains mechanically compatible. The Eaton SR-5 series parts measure 0.335" Dia x 0.319" H (8.50mm x 8.10mm), representing a 0.004" height increase.

Q: Which substitute part offers the broadest approval agency coverage?

A: The Bel Fuse Inc. MRF 4-BULK carries the most comprehensive certification portfolio: AEC-Q200, CE, CSA, cULus, PSE, SEMKO, and VDE. This part is suitable for applications requiring automotive qualification or multi-regional compliance.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All listed substitute parts maintain ROHS3 compliance status, matching the environmental compliance profile of the primary Littelfuse 37014000000 part.

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