Littelfuse 0325.300H Ceramic Cartridge Fuse – Equivalent & Substitute Parts

Part Overview

The Littelfuse 0325.300H is a 300 mA, 250 V AC ceramic cartridge fuse in 3AB/3AG package format (1/4" x 1-1/4" axial). This fuse is classified as obsolete, making equivalent substitute parts necessary for ongoing circuit protection applications requiring identical electrical and mechanical specifications. The part features slow-blow response characteristics and is rated for 100 A breaking capacity at rated voltage.

Key Parameters

Parameter	Value
Current Rating	300 mA
Voltage Rating – AC	250 V
Fuse Type	Cartridge, Ceramic
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Response Time	Slow Blow
Breaking Capacity @ Rated Voltage	100 A
Melting I²t	0.69
DC Cold Resistance	3.2 Ohms
Size / Dimension	0.275" Dia x 1.288" L (6.99mm x 32.72mm)
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitute parts for the 0325.300H are qualified based on the following critical parameters that must remain constant:

Current Rating: 300 mA (exact match required)
Voltage Rating – AC: 250 V (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Fuse Type: Cartridge, Ceramic (exact match required)
Response Time: Slow Blow (exact match required)
Melting I²t: 0.69 (exact match required)
Size / Dimension: 0.275" Dia x 1.288" L (6.99mm x 32.72mm) (exact match required)

The three substitute parts listed below meet all these criteria. The primary distinction between the main part and substitutes is product status and compliance certifications. The substitute parts include DC voltage ratings (125 V DC) and enhanced operating temperature ranges, representing active production alternatives with improved compliance profiles.

Parameter Comparison

Parameter	0325.300H (Main)	0325.300HXP	0325.300MXP	0325.300VXP
Current Rating (Amps)	300 mA	300 mA	300 mA	300 mA
Voltage Rating – AC	250 V	250 V	250 V	250 V
Voltage Rating – DC	Not specified	125 V	125 V	125 V
Fuse Type	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic
Package / Case	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Breaking Capacity @ Rated Voltage	100 A	100 A AC, 10 kA DC	100 A AC, 10 kA DC	100 A AC, 10 kA DC
Melting I²t	0.69	0.69	0.69	0.69
DC Cold Resistance	3.2 Ohms	3.22 Ohms	3.22 Ohms	3.22 Ohms
Size / Dimension	0.275" Dia x 1.288" L	0.275" Dia x 1.288" L	0.275" Dia x 1.288" L	0.275" Dia x 1.288" L
Operating Temperature	Not specified	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, UL	CE, CSA, UL	CE, CSA, UL	CE, CSA, UL

Engineering Selection Recommendations

All three substitute parts (0325.300HXP, 0325.300MXP, 0325.300VXP) are direct functional equivalents to the obsolete 0325.300H, maintaining identical electrical performance for AC circuit protection at 300 mA and 250 V. The substitutes are active production parts with enhanced compliance certifications including CE marking and ROHS3 compliance, compared to the non-compliant status of the main part.

The substitute parts provide additional DC voltage rating capability (125 V DC) and defined operating temperature ranges (-55°C ~ 125°C), which represent engineering improvements without altering AC circuit protection characteristics. All three substitutes carry identical electrical parameters: current rating, voltage rating, response time, melting I²t, and package dimensions.

Selection among the three substitute parts should be based on inventory availability and packaging requirements, as all three are electrically and mechanically interchangeable for the 0325.300H application.

Frequently Asked Questions (FAQ)

Q: Can the substitute parts directly replace the 0325.300H in existing designs?

A: Yes. The substitute parts 0325.300HXP, 0325.300MXP, and 0325.300VXP are direct replacements. All maintain the same current rating (300 mA), AC voltage rating (250 V), package format (3AB/3AG, 1/4" x 1-1/4"), response time (slow blow), and melting I²t (0.69). Physical dimensions and mounting type are identical.

Q: What is the difference between the three substitute parts?

A: The three substitute parts (0325.300HXP, 0325.300MXP, 0325.300VXP) are parametrically equivalent. All share identical electrical and mechanical specifications. Differences are limited to packaging format (all listed as Bulk) and inventory availability. Selection should be based on supply chain availability.

Q: Why do the substitute parts have DC voltage ratings when the original part does not?

A: The substitute parts include DC voltage ratings (125 V DC) as part of their specification. This represents an enhancement in the product definition and does not affect AC circuit protection performance. For AC-only applications, the DC rating is not a limiting factor.

Q: Are the substitute parts RoHS compliant?

A: Yes. All three substitute parts (0325.300HXP, 0325.300MXP, 0325.300VXP) are ROHS3 compliant, whereas the original 0325.300H is RoHS non-compliant. This is an improvement for applications requiring RoHS compliance.

Q: Do the substitute parts have the same approval certifications?

A: The substitute parts carry CE, CSA, and UL certifications, compared to CSA and UL for the original part. The addition of CE marking represents expanded regulatory approval.

Q: Are there any mechanical compatibility concerns when substituting these parts?

A: No. All substitute parts maintain the identical 3AB/3AG package format, 1/4" x 1-1/4" (axial) dimensions, and through-hole mounting type. Direct mechanical substitution is supported without PCB or fixture modifications.

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