Littelfuse 02301.25MXSP Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 02301.25MXSP is a 1.25 A, 250 V AC / 125 V DC glass cartridge fuse with slow-blow response characteristics, designed for through-hole mounting in non-standard axial configurations. This part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain identical electrical and mechanical specifications for seamless circuit protection replacement.

Key Parameters

Parameter	Value
Current Rating	1.25 A
Voltage Rating (AC)	250 V
Voltage Rating (DC)	125 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Mounting Type	Through Hole
Package / Case	Cartridge, Non-Standard (Axial)
Size / Dimension	0.177" Dia x 0.571" L (4.50mm x 14.50mm)
Melting I²t	9.8
DC Cold Resistance	0.146 Ohms
Operating Temperature Range	-55°C ~ 125°C
Approval Agencies	CE, CSA, PSE, UL
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the 02301.25MXSP is determined by strict equivalence across the following critical parameters:

Current Rating: 1.25 A (exact match required)
Voltage Rating AC: 250 V (exact match required)
Voltage Rating DC: 125 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: Cartridge, Non-Standard (Axial) (exact match required)
Size / Dimension: 0.177" Dia x 0.571" L (4.50mm x 14.50mm) (exact match required)
Melting I²t: 9.8 (exact match required)
DC Cold Resistance: 0.146 Ohms (exact match required)
Operating Temperature Range: -55°C ~ 125°C (exact match required)
Approval Agencies: CE, CSA, PSE, UL (exact match required)
RoHS Status: ROHS3 Compliant (exact match required)

All substitute parts listed below meet these criteria. Variations in breaking capacity do not affect substitution eligibility for this product category, as breaking capacity represents an enhanced performance characteristic rather than a limiting constraint for standard circuit protection applications.

Parameter Comparison

Parameter	02301.25MXSP (Main)	02301.25HXP	02301.25HXSP	02301.25MXP	02301.25VXP
Current Rating (Amps)	1.25 A	1.25 A	1.25 A	1.25 A	1.25 A
Voltage Rating - AC	250 V	250 V	250 V	250 V	250 V
Voltage Rating - DC	125 V	125 V	125 V	125 V	125 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Cartridge, Non-Standard (Axial)	Cartridge, Non-Standard (Axial)	Cartridge, Non-Standard (Axial)	Cartridge, Non-Standard (Axial)	Cartridge, Non-Standard (Axial)
Size / Dimension	0.177" Dia x 0.571" L (4.50mm x 14.50mm)	0.177" Dia x 0.571" L (4.50mm x 14.50mm)	0.177" Dia x 0.571" L (4.50mm x 14.50mm)	0.177" Dia x 0.571" L (4.50mm x 14.50mm)	0.177" Dia x 0.571" L (4.50mm x 14.50mm)
Melting I²t	9.8	9.8	9.8	9.8	9.8
DC Cold Resistance	0.146 Ohms	0.146 Ohms	0.146 Ohms	0.146 Ohms	0.146 Ohms
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Approval Agency	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Product Status	Obsolete	Active	Active	Active	Active
Breaking Capacity @ Rated Voltage	35A AC, 10kA DC	35A AC, 10kA DC	35A AC, 10kA DC	35A AC, 10kA DC	100A AC, 10kA DC

Engineering Selection Recommendations

All four substitute parts—02301.25HXP, 02301.25HXSP, 02301.25MXP, and 02301.25VXP—are direct parametric equivalents to the obsolete 02301.25MXSP. Each maintains identical electrical characteristics, mechanical dimensions, thermal operating range, and regulatory certifications (CE, CSA, PSE, UL) with ROHS3 compliance.

Selection among active alternatives should prioritize availability and supply chain continuity. The 02301.25MXP offers the highest inventory level (19,895 units), followed by 02301.25HXP (850 units), 02301.25VXP (952 units), and 02301.25HXSP (752 units). The 02301.25VXP provides enhanced breaking capacity at 100A AC compared to the standard 35A AC rating of other variants, representing an upgraded performance option where circuit protection requirements exceed baseline specifications.

Frequently Asked Questions (FAQ)

Q: Can the 02301.25HXP, 02301.25HXSP, 02301.25MXP, or 02301.25VXP be used as direct replacements for the 02301.25MXSP?

A: Yes. All four parts are parametric equivalents with identical current ratings (1.25 A), voltage ratings (250 V AC / 125 V DC), response characteristics (slow-blow), physical dimensions (0.177" Dia x 0.571" L), and thermal operating ranges (-55°C ~ 125°C). They maintain the same melting I²t value (9.8) and DC cold resistance (0.146 Ohms), ensuring equivalent circuit protection performance.

Q: What is the difference between these substitute parts?

A: The primary differences are product status and availability. The 02301.25MXSP is obsolete; all substitutes are active. The 02301.25VXP offers enhanced breaking capacity (100A AC versus 35A AC), providing superior fault current handling capability. Packaging is bulk for all active alternatives.

Q: Are there any compatibility concerns with through-hole mounting?

A: No. All parts share identical mounting type (through-hole) and non-standard axial cartridge configuration, ensuring mechanical compatibility with existing PCB footprints and holder assemblies designed for the 02301.25MXSP.

Q: Do all substitutes meet the same regulatory certifications?

A: Yes. All substitute parts carry CE, CSA, PSE, and UL approvals with ROHS3 compliance, matching the certification profile of the main part.

Q: Which substitute should be selected for new designs?

A: The 02301.25MXP is recommended for new designs based on superior inventory availability and active product status. The 02301.25VXP is appropriate where enhanced breaking capacity (100A AC) is required for high-fault-current applications.

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