Littelfuse 0325.400H Ceramic Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0325.400H is a 400 mA, 250 V AC ceramic cartridge fuse with slow-blow response characteristics, designed for through-hole mounting in 3AB/3AG package format (1/4" x 1-1/4" axial). This part is classified as obsolete. Equivalent substitute parts are available from the same manufacturer series with enhanced specifications, including DC voltage rating capability and active product status, making them suitable replacements for new designs and ongoing applications.

Key Parameters

Parameter	Value
Current Rating	400 mA
Voltage Rating - AC	250 V
Fuse Type	Cartridge, Ceramic
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Mounting Type	Through Hole
Breaking Capacity @ Rated Voltage	100A
Size / Dimension	0.275" Dia x 1.288" L (6.99mm x 32.72mm)

Substitute Part Grouping Explanation

Substitution of the 0325.400H is determined by the following critical parameters:

Current Rating: 400 mA (exact match required)
Voltage Rating - AC: 250 V (exact match required)
Fuse Type: Cartridge, Ceramic (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Mounting Type: Through Hole (exact match required)
Melting I²t: 1.33 (exact match required)

The substitute parts 0325.400HXP, 0325.400MXP, and 0325.400VXP meet all critical electrical and mechanical parameters. These parts are direct functional equivalents with the addition of DC voltage rating (125 V DC) and enhanced operational temperature range (-55°C ~ 125°C), representing active product alternatives to the obsolete 0325.400H.

Parameter Comparison

Parameter	0325.400H (Main)	0325.400HXP	0325.400MXP	0325.400VXP
Current Rating (Amps)	400 mA	400 mA	400 mA	400 mA
Voltage Rating - AC	250 V	250 V	250 V	250 V
Voltage Rating - DC	—	125 V	125 V	125 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Breaking Capacity @ Rated Voltage	100A	100A AC, 10kA DC	100A AC, 10kA DC	100A AC, 10kA DC
Melting I²t	1.33	1.33	1.33	1.33
DC Cold Resistance	1.92 Ohms	1.935 Ohms	1.935 Ohms	1.935 Ohms
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
Operating Temperature	—	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C

Engineering Selection Recommendations

The 0325.400H is obsolete and no longer in active production. The substitute parts 0325.400HXP, 0325.400MXP, and 0325.400VXP are functionally equivalent and recommended for component replacement in new designs and ongoing applications.

All three substitute parts maintain identical AC voltage and current ratings, response characteristics, and mechanical dimensions. The substitute parts offer the following advantages:

Active Product Status: Currently manufactured and supported by Littelfuse Inc.
Enhanced Compliance: ROHS3 compliant (versus RoHS non-compliant for the main part)
Extended Certifications: CE certification added to existing CSA and UL approvals
DC Voltage Capability: 125 V DC rating enables use in mixed AC/DC applications
Defined Operating Temperature Range: -55°C ~ 125°C operational specification
Improved Breaking Capacity: 10kA DC breaking capacity in addition to 100A AC

Selection among the three substitute parts (0325.400HXP, 0325.400MXP, 0325.400VXP) is based on packaging and inventory availability, as all three are electrically and mechanically identical.

Frequently Asked Questions (FAQ)

Q: Can the 0325.400HXP, 0325.400MXP, or 0325.400VXP be used as direct replacements for the 0325.400H?

A: Yes. All three substitute parts are direct functional equivalents. They maintain the same 400 mA current rating, 250 V AC voltage rating, slow-blow response, ceramic cartridge construction, and 3AB/3AG package format. The substitute parts are physically and electrically compatible with applications designed for the 0325.400H.

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

A: The 0325.400HXP, 0325.400MXP, and 0325.400VXP are electrically and mechanically identical. Differences exist only in packaging format (all specified as Bulk) and inventory availability. Selection should be based on procurement requirements and stock availability.

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

A: No. The 250 V AC rating remains unchanged. The 125 V DC rating is an additional capability that does not impact performance in AC-only circuits. The substitute parts are fully backward compatible with the original 0325.400H specification for AC applications.

Q: Are the substitute parts RoHS compliant?

A: Yes. All three substitute parts (0325.400HXP, 0325.400MXP, 0325.400VXP) are ROHS3 compliant, whereas the original 0325.400H is RoHS non-compliant. This makes the substitute parts suitable for applications with RoHS compliance requirements.

Q: What certifications do the substitute parts carry?

A: The substitute parts carry CE, CSA, and UL certifications. The original 0325.400H carries CSA and UL certifications only. The addition of CE certification on the substitute parts extends regulatory approval coverage.

Q: Are the physical dimensions identical between the main part and substitute parts?

A: Yes. All parts share identical dimensions: 0.275" Dia x 1.288" L (6.99mm x 32.72mm). The 3AB/3AG package format and through-hole mounting type are identical, ensuring mechanical compatibility in existing PCB designs and fuse holders.

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