Equivalent & Substitute Parts for 02191.25MXAF5P

Part Overview

The Littelfuse 02191.25MXAF5P is a 1.25 A, 250 V AC/DC glass cartridge fuse in 5mm x 20mm form factor with slow blow response characteristics. This fuse is designed for circuit protection in applications requiring moderate current limiting with extended response time. The part is active in production with 854 units currently in stock. Alternative equivalent parts may be required due to supply constraints, regional certification requirements, or specific application performance parameters.

Key Parameters

Parameter	Value
Current Rating	1.25 A
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	150 A
Melting I²t	27.15
Operating Temperature Range	-55°C ~ 125°C
DC Cold Resistance	0.0817 Ohms
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 02191.25MXAF5P is determined by the following mandatory parameters:

Current Rating: 1.25 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Requires Holder (exact match required)

Substitute parts are grouped into two categories:

Littelfuse Series Equivalents: Parts from Littelfuse 213, 218, and 239 series maintain identical electrical and mechanical specifications with variations in breaking capacity and melting I²t characteristics. These parts are direct parametric equivalents suitable for applications where the primary circuit protection parameters are identical.

Cross-Manufacturer Equivalents: SCHURTER and OptiFuse parts meeting all mandatory parameters provide alternative sourcing options with equivalent performance characteristics and compliance certifications.

Parameter Comparison

Part Number	Manufacturer	Series	Current (A)	Voltage AC (V)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Resistance (Ω)	Inventory (Pcs)
02191.25MXAF5P	Littelfuse	219XA	1.25	250	Slow Blow	5x20mm	150	27.15	0.0817	854
02131.25MXP	Littelfuse	213	1.25	250	Slow Blow	5x20mm	35	27.15	0.0817	3448
02181.25HXP	Littelfuse	218	1.25	250	Slow Blow	5x20mm	35	12.65	0.0446	5238
02181.25MXP	Littelfuse	218	1.25	250	Slow Blow	5x20mm	35	12.65	0.0446	4296
02181.25TXP	Littelfuse	218	1.25	250	Slow Blow	5x20mm	35	12.65	0.0446	1155
02191.25MXAP	Littelfuse	219XA	1.25	250	Slow Blow	5x20mm	150	27.15	0.0817	1587
02391.25HXP	Littelfuse	239	1.25	250	Slow Blow	5x20mm	100	19.525	0.198	881
0034.3118	SCHURTER	FST 5x20	1.25	250	Slow Blow	5x20mm	35	5.5	—	13782
0034.5618.11	SCHURTER	SMD-FST	1.25	250	Slow Blow	5x20mm	35	5.5	—	1181
TSC-1.25A	OptiFuse	TSC	1.25	250	Slow Blow	5x20mm	100	4.07	—	4533

Engineering Selection Recommendations

Primary Equivalents (Littelfuse 219XA Series): The 02191.25MXAP maintains identical electrical characteristics, breaking capacity, and melting I²t to the primary part. Both parts carry equivalent compliance certifications (CCC, CE, CSA, PSE, SEMKO, UL, VDE) and are suitable for direct substitution in applications requiring 150 A breaking capacity.

Secondary Equivalents (Littelfuse 213 and 218 Series): Parts 02131.25MXP, 02181.25HXP, 02181.25MXP, and 02181.25TXP meet all mandatory electrical and mechanical parameters. These parts feature reduced breaking capacity (35 A) and lower melting I²t values. Selection depends on application requirements where lower breaking capacity is acceptable. All parts maintain ROHS3 compliance and broad certification coverage.

Alternative Capacity Option (Littelfuse 239 Series): The 02391.25HXP provides intermediate breaking capacity (100 A) with melting I²t of 19.525. This part is suitable for applications requiring performance between standard 35 A and 150 A breaking capacity ratings.

Cross-Manufacturer Options: SCHURTER FST 5x20 series (0034.3118) and SMD-FST series (0034.5618.11) provide equivalent parametric performance with reduced melting I²t (5.5). OptiFuse TSC-1.25A offers 100 A breaking capacity with the lowest melting I²t (4.07). Cross-manufacturer selection should account for regional certification requirements and supply chain considerations.

Frequently Asked Questions (FAQ)

Q: Can I substitute a part with different breaking capacity? A: Breaking capacity is a critical parameter determined by application circuit requirements. Parts with lower breaking capacity (35 A) are suitable only for applications where the circuit fault current does not exceed this rating. Parts with higher breaking capacity (100 A or 150 A) provide additional margin but do not affect normal operation at rated current.

Q: Are all substitute parts ROHS3 compliant? A: All listed substitute parts carry ROHS3 compliance certification. Compliance status is identical across all options.

Q: What is the significance of melting I²t variation? A: Melting I²t indicates the thermal energy required to melt the fuse element. Lower values result in faster response to overcurrent conditions. Selection should match application thermal time constant requirements. The primary part (27.15) and 02131.25MXP (27.15) provide identical thermal response, while 218 series parts (12.65) and cross-manufacturer options (4.07–5.5) provide faster response characteristics.

Q: Can I use parts with different DC cold resistance? A: DC cold resistance affects voltage drop under normal operating current. The primary part and 02131.25MXP both measure 0.0817 Ohms. Littelfuse 218 series parts measure 0.0446 Ohms (lower drop), while 02391.25HXP measures 0.198 Ohms (higher drop). Selection should account for circuit voltage budget and thermal dissipation requirements.

Q: Are SCHURTER and OptiFuse parts direct replacements? A: SCHURTER and OptiFuse parts meet all mandatory electrical and mechanical parameters (1.25 A, 250 V AC, 5x20mm, slow blow, cartridge glass). Differences in breaking capacity and melting I²t require application-specific evaluation. Regional certification requirements may influence selection.

Q: What certifications are most critical for my application? A: Certification requirements depend on end-use application and regional standards. All listed parts carry CCC, CE, CSA, PSE, and VDE certifications. Specific applications may require additional certifications such as UL, K-MARK, or KC. Verify certification alignment with application requirements before selection.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message