Littelfuse 021902.5TXAP Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 021902.5TXAP is a 2.5 A, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm form factor. This fuse is designed for circuit protection in applications requiring slow-blow response characteristics and is currently in active production status. Equivalent and substitute parts are identified based on matching electrical ratings, mechanical dimensions, response time classification, and approval certifications to ensure direct functional compatibility in circuit protection applications.

Key Parameters

Parameter	Value
Current Rating	2.5 A
Voltage Rating (AC)	250 V
Voltage Rating (DC)	DC Rated
Response Time	Slow Blow
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Mounting Type	Requires Holder
Operating Temperature Range	-55°C ~ 125°C
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 021902.5TXAP is determined by the following critical parameters:

Primary Matching Criteria:

Current Rating: 2.5 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Operating Temperature Range: -55°C ~ 125°C (minimum requirement)

Secondary Considerations:

Breaking Capacity @ Rated Voltage (varies among substitutes)
Melting I²t (varies among substitutes)
DC Cold Resistance (varies among substitutes)
Approval Agency certifications (must maintain compliance requirements)

Parts meeting all primary criteria are classified as parametric equivalents. Variations in breaking capacity, melting I²t, and resistance are acceptable provided the application does not impose specific requirements for these parameters.

Parameter Comparison

Part Number	Manufacturer	Series	Current (A)	Voltage AC (V)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Resistance (Ω)	Temp Range (°C)
021902.5TXAP	Littelfuse Inc.	219XA	2.5	250	Slow Blow	5x20mm	150	138	0.0305	-55 ~ 125
021302.5MXP	Littelfuse Inc.	213	2.5	250	Slow Blow	5x20mm	35	138	0.0305	-55 ~ 125
021802.5HXP	Littelfuse	218	2.5	250	Slow Blow	5x20mm	35	23.25	0.0219	-55 ~ 125
021802.5TXP	Littelfuse Inc.	218	2.5	250	Slow Blow	5x20mm	35	23.25	0.0219	-55 ~ 125
021902.5MXAP	Littelfuse	219XA	2.5	250	Slow Blow	5x20mm	150	138	0.0305	-55 ~ 125
023902.5HXP	Littelfuse	239	2.5	250	Slow Blow	5x20mm	100	79.705	0.0583	-55 ~ 125
023902.5MXP	Littelfuse	239	2.5	250	Slow Blow	5x20mm	100	79.705	0.0583	-55 ~ 125
0034.3121	SCHURTER Inc.	FST 5x20	2.5	250	Slow Blow	5x20mm	35	21.9	—	-55 ~ 125
0034.5621.11	SCHURTER Inc.	SMD-FST	2.5	250	Slow Blow	5x20mm	35	21.9	—	-55 ~ 125
0034.5717.11	SCHURTER Inc.	SMD-FTT	2.5	250	Slow Blow	5x20mm	35	258	—	-55 ~ 125

Engineering Selection Recommendations

All listed substitute parts meet the primary electrical and mechanical matching criteria for the 021902.5TXAP. Selection among equivalents should be based on the following factors:

Littelfuse 219XA Series (021902.5TXAP, 021902.5MXAP): These parts share identical electrical characteristics and breaking capacity (150 A). Both are ROHS3 compliant and maintain the full operating temperature range. The 021902.5MXAP provides equivalent functionality with 1,000 pcs inventory availability.

Littelfuse 218 Series (021802.5HXP, 021802.5TXP): These parts provide lower melting I²t (23.25 vs. 138) and reduced DC cold resistance (0.0219 Ω vs. 0.0305 Ω). Breaking capacity is reduced to 35 A. Both maintain full temperature range and ROHS3 compliance. Certification coverage differs: 021802.5HXP includes K-MARK; 021802.5TXP includes KC.

Littelfuse 213 Series (021302.5MXP): Provides identical melting I²t and DC resistance to the main part but with reduced breaking capacity (35 A). Certification includes BSI in addition to standard approvals.

Littelfuse 239 Series (023902.5HXP, 023902.5MXP): These parts feature intermediate breaking capacity (100 A) and melting I²t (79.705). DC cold resistance is higher (0.0583 Ω). Certification coverage is more limited (CE, CSA, KC, PSE, UL only).

SCHURTER FST/SMD Series (0034.3121, 0034.5621.11, 0034.5717.11): All SCHURTER glass cartridge fuses meet primary electrical criteria. The 0034.3121 and 0034.5621.11 share melting I²t of 21.9. The 0034.5717.11 features significantly higher melting I²t (258). Certification coverage is limited to cURus and/or VDE. Operating temperature range matches the main part.

Note on 0034.2520: This SCHURTER ceramic fuse does not qualify as a substitute. Although it matches current rating, voltage, and package, it is classified as medium-blow response rather than slow-blow, making it functionally incompatible.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with different breaking capacity? A: Yes, provided the application does not impose specific breaking capacity requirements. Breaking capacity indicates the maximum fault current the fuse can safely interrupt. Lower breaking capacity (35 A vs. 150 A) is acceptable in applications with fault currents below that threshold. Higher breaking capacity provides additional safety margin.

Q: What is the significance of melting I²t variation among substitutes? A: Melting I²t characterizes the thermal energy required to melt the fuse element. Variations indicate different thermal response profiles. Lower melting I²t (21.9 to 23.25) results in faster thermal response; higher values (138 to 258) result in slower response. All listed substitutes maintain slow-blow classification and are compatible with the 021902.5TXAP application.

Q: Are SCHURTER parts direct replacements for Littelfuse parts? A: SCHURTER glass cartridge fuses meeting all primary criteria (2.5 A, 250 V AC, slow-blow, 5x20mm) are parametric equivalents. Physical dimensions and electrical performance are compatible. Certification differences should be verified against application compliance requirements.

Q: Why is the 0034.2520 ceramic fuse not listed as a substitute? A: The 0034.2520 is classified as medium-blow response, not slow-blow. Response time classification is a primary matching criterion. Additionally, it is rated for 125 V DC maximum, whereas the 021902.5TXAP is rated for full AC/DC operation. These differences make it functionally incompatible.

Q: Does DC cold resistance variation affect substitution? A: DC cold resistance affects voltage drop and heat generation under normal operating conditions. Variations from 0.0219 Ω to 0.0583 Ω are within acceptable ranges for cartridge fuses. Selection should consider application thermal constraints if resistance variation is critical.

Q: What certifications are required for my application? A: Certification requirements depend on end-use application and regional standards. The main part 021902.5TXAP carries CCC, CE, CSA, PSE, SEMKO, UL, and VDE approvals. Substitute parts carry varying certification subsets. Verify that selected substitute meets all mandatory certifications for your application jurisdiction.

Q: Can I substitute a Littelfuse part with a SCHURTER part in existing designs? A: Yes, provided all primary electrical and mechanical criteria match and certification requirements are satisfied. Physical compatibility is ensured by identical 5x20mm package dimensions and cartridge fuse holder requirements. Thermal and electrical performance differences should be evaluated for specific applications.

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