Littelfuse 02301.25HXSW Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 02301.25HXSW is a 1.25 A, 250 V AC glass cartridge fuse with slow-blow response characteristics, designed for through-hole mounting in axial configuration. This part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain electrical and mechanical compatibility. Substitute parts must preserve the 1.25 A current rating, 250 V AC voltage rating, slow-blow response time, and non-standard axial cartridge form factor to ensure proper circuit protection function.

Key Parameters

Parameter	Value
Manufacturer Part Number	02301.25HXSW
Manufacturer	Littelfuse Inc.
Current Rating	1.25 A
Voltage Rating - AC	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	Cartridge, Non-Standard (Axial)
Mounting Type	Through Hole
Size / Dimension	0.177" Dia x 0.571" L (4.50mm x 14.50mm)
Operating Temperature Range	-55°C ~ 125°C
Melting I²t	9.8
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution of the 02301.25HXSW is determined by strict equivalence in the following electrical and mechanical parameters:

Current Rating: 1.25 A (exact match required)
Voltage Rating - AC: 250 V (exact match required)
Response Time: Slow Blow (exact match required)
Fuse Type: Cartridge, Glass (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)
Mounting Type: Through Hole (exact match required)

All identified substitute parts maintain these core parameters. Variations in DC voltage rating, breaking capacity, RoHS compliance status, and approval agency certifications do not affect substitutability for AC-rated applications but may influence selection based on system requirements.

Parameter Comparison

Parameter	02301.25HXSW (Main)	02301.25HXSP	02301.25HXP	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	Not specified	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
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 (Ohms)	0.145	0.146	0.146	0.146	0.146
Operating Temperature Range	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Product Status	Obsolete	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Breaking Capacity @ Rated Voltage	100A	35A AC, 10kA DC	35A AC, 10kA DC	35A AC, 10kA DC	100A AC, 10kA DC
Approval Agency	CSA, METI, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL

Engineering Selection Recommendations

All four substitute parts (02301.25HXSP, 02301.25HXP, 02301.25MXP, 02301.25VXP) are electrically and mechanically equivalent to the 02301.25HXSW for AC circuit protection applications. Selection among these active alternatives should be based on the following criteria:

Product Availability: 02301.25MXP offers the highest inventory level (19,895 pcs), followed by 02301.25HXP (850 pcs), 02301.25VXP (952 pcs), and 02301.25HXSP (752 pcs).

Compliance Requirements: All substitute parts are ROHS3 compliant and carry CE, CSA, PSE, and UL certifications, providing broader regulatory coverage than the obsolete main part. The 02301.25HXSP includes PSE approval, which may be required for specific markets.

Breaking Capacity Considerations: The 02301.25VXP provides 100A AC breaking capacity, matching the main part specification. The 02301.25HXSP, 02301.25HXP, and 02301.25MXP provide 35A AC breaking capacity. Selection should align with system fault current requirements.

DC Voltage Rating: All substitute parts include 125 V DC rating, providing additional functionality not specified in the main part. This does not affect AC-only applications.

Frequently Asked Questions (FAQ)

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

A: Yes. All four parts maintain identical current rating (1.25 A), AC voltage rating (250 V), response time (slow blow), fuse type (cartridge glass), package configuration (non-standard axial), physical dimensions (0.177" Dia x 0.571" L), and melting I²t (9.8). They are electrically and mechanically equivalent for AC circuit protection applications.

Q: What is the difference between the substitute parts?

A: The primary differences are product status (all substitutes are active versus the obsolete main part), inventory availability, breaking capacity ratings, and regulatory certifications. All substitute parts are ROHS3 compliant with enhanced certification coverage (CE, CSA, PSE, UL). The 02301.25VXP provides 100A AC breaking capacity matching the main part, while others provide 35A AC breaking capacity.

Q: Does the DC voltage rating on substitute parts affect AC-only applications?

A: No. The 125 V DC rating on substitute parts does not impact performance in AC-only circuits. This specification provides additional capability for dual AC/DC applications if required.

Q: Are there any physical or mounting differences between the main part and substitutes?

A: No. All parts share identical physical dimensions (0.177" Dia x 0.571" L / 4.50mm x 14.50mm), through-hole mounting type, and axial cartridge configuration. Direct mechanical substitution is supported without modification to circuit board layouts or holder assemblies.

Q: Which substitute part should be selected for new designs?

A: For new designs, any of the four active substitute parts is acceptable based on availability and system requirements. The 02301.25MXP offers superior availability. The 02301.25VXP should be selected if 100A AC breaking capacity is required to match the original specification.

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