Equivalent & Substitute Parts for 5STP 2.5

Part Overview

The 5STP 2.5 is a 2.5 A, 250 V AC/DC slow-blow glass cartridge fuse with a 5mm x 20mm axial form factor, manufactured by Bel Fuse Inc. This part is classified as obsolete. Equivalent and substitute parts are available from active product lines that maintain the same electrical ratings, mechanical dimensions, and functional characteristics required for direct replacement in circuit protection applications.

Key Parameters

Parameter	Value
Current Rating	2.5 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm (Axial)
Mounting Type	Through Hole
Operating Temperature Range	-55°C ~ 125°C
Breaking Capacity @ Rated Voltage	35 A

Substitute Part Grouping Explanation

Substitution for the 5STP 2.5 is determined by strict equivalence across the following parameters: current rating (2.5 A), voltage rating (250 V AC), fuse type (cartridge glass), response time (slow blow), package dimensions (5mm x 20mm axial), and mounting type (through hole). All substitute parts listed maintain these core electrical and mechanical specifications. Variations in breaking capacity, melting I²t, DC cold resistance, and approval agencies are noted but do not preclude functional substitution when the primary electrical and mechanical parameters align.

Parameter Comparison

Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
5STP 2.5	Bel Fuse Inc.	2.5	250	Slow Blow	5mm x 20mm	35	20	0.02	Obsolete	RoHS non-compliant
5STP 2.5-R	Bel Fuse Inc.	2.5	250	Slow Blow	5mm x 20mm	35	20	0.02	Active	ROHS3 Compliant
5ETP 2.5-R	Bel Fuse Inc.	2.5	250	Slow Blow	5mm x 20mm	150	137	0.031	Active	ROHS3 Compliant
5TTP 2.5-R	Bel Fuse Inc.	2.5	250	Slow Blow	5mm x 20mm	100	45.2	0.06	Active	ROHS3 Compliant
0034.3121.PT	SCHURTER Inc.	2.5	250	Slow Blow	5mm x 20mm	35	21.9	—	Active	ROHS3 Compliant
021302.5MRET1P	Littelfuse Inc.	2.5	250	Slow Blow	5mm x 20mm	35	138	0.0305	Active	ROHS3 Compliant
021802.5MXEP	Littelfuse Inc.	2.5	250	Slow Blow	5mm x 20mm	35	23.25	0.0219	Active	ROHS3 Compliant

Engineering Selection Recommendations

For direct replacement of the obsolete 5STP 2.5, the 5STP 2.5-R from Bel Fuse Inc. is the primary equivalent, offering identical electrical and mechanical specifications with active product status and ROHS3 compliance.

The 5ETP 2.5-R and 5TTP 2.5-R from Bel Fuse Inc. are parametric equivalents that maintain the same current, voltage, and response time ratings. These parts differ in breaking capacity and melting I²t characteristics, reflecting different internal fuse element designs. Selection between these variants depends on the specific breaking capacity requirement of the application.

The 0034.3121.PT from SCHURTER Inc. is a direct equivalent with matching breaking capacity and active status. Minor dimensional variations exist (5.40mm diameter vs. 5.50mm, 22.50mm length vs. 21.00mm), which may affect fit in legacy fuse holders designed for the original 5STP 2.5 specifications.

The 021302.5MRET1P and 021802.5MXEP from Littelfuse Inc. are functionally equivalent parts available in different packaging formats (tape & reel and bulk, respectively). Both maintain the required electrical ratings and are ROHS3 compliant. Dimensional variations (5.80mm diameter, 22.50mm length) should be evaluated against mechanical constraints in the target application.

Frequently Asked Questions (FAQ)

Q: Can the 5STP 2.5-R be used as a direct replacement for the obsolete 5STP 2.5?

A: Yes. The 5STP 2.5-R maintains identical current rating (2.5 A), voltage rating (250 V AC), response time (slow blow), and package dimensions (5mm x 20mm). The primary difference is product status (active vs. obsolete) and RoHS compliance (ROHS3 vs. non-compliant).

Q: What is the difference between the 5STP 2.5-R, 5ETP 2.5-R, and 5TTP 2.5-R?

A: All three parts share the same current, voltage, and response time ratings. They differ in breaking capacity and melting I²t values, which reflect different fuse element designs. The 5STP 2.5-R has a breaking capacity of 35 A with melting I²t of 20. The 5ETP 2.5-R has a breaking capacity of 150 A with melting I²t of 137. The 5TTP 2.5-R has a breaking capacity of 100 A with melting I²t of 45.2. Selection depends on the application's breaking capacity requirement.

Q: Are there dimensional differences between substitute parts?

A: Yes. The original 5STP 2.5 has dimensions of 5.50mm diameter x 21.00mm length. The SCHURTER 0034.3121.PT measures 5.40mm diameter x 22.50mm length. The Littelfuse parts (021302.5MRET1P and 021802.5MXEP) measure 5.80mm diameter x 22.50mm length. These variations may affect mechanical fit in fuse holders designed for the original specifications.

Q: Which substitute part has the best RoHS compliance status?

A: All active substitute parts listed (5STP 2.5-R, 5ETP 2.5-R, 5TTP 2.5-R, 0034.3121.PT, 021302.5MRET1P, and 021802.5MXEP) are ROHS3 compliant. The original 5STP 2.5 is RoHS non-compliant.

Q: What packaging options are available for substitutes?

A: The 5STP 2.5-R, 5ETP 2.5-R, 5TTP 2.5-R, 0034.3121.PT, and 021802.5MXEP are available in bulk packaging. The 021302.5MRET1P is available in tape & reel (TR) packaging, suitable for automated assembly processes.

Q: Can I use a substitute part with a higher breaking capacity?

A: Yes, provided the application does not require the specific breaking capacity of the original part. The 5ETP 2.5-R (150 A breaking capacity) and 5TTP 2.5-R (100 A breaking capacity) are functionally equivalent for applications where higher breaking capacity is acceptable or beneficial.

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