Littelfuse 0328021.MXP Ceramic Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0328021.MXP is a 21 A ceramic cartridge fuse rated for 300 V AC and 100 V DC operation. This slow-blow fuse is designed for applications requiring holder-based mounting in 3AB, 3AG configurations with 1/4" x 1-1/4" dimensions. The part is currently active in production with full inventory availability. Substitute parts are identified to provide alternative sourcing options when the primary part is unavailable or when system voltage ratings permit higher-rated alternatives.

Substiute Parts

0328021.MXP

Littelfuse Inc.In Stock: 16850328021.MXP Datasheet

Current PartRFQ

MDH-21-R-BK

Eaton - Electronics DivisionIn Stock: 991MDH-21-R-BK Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The Eaton MDH-21-R-BK qualifies as a direct substitute based on the following critical parameters:

Matching Parameters:

• Current Rating: 21 A (identical)
• Fuse Type: Cartridge, Ceramic (identical)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (identical)
• Physical Dimensions: 0.250" Dia x 1.250" L (identical)
• Breaking Capacity: 200 A (identical)
• Operating Temperature Range: -55°C ~ 125°C (identical)
• Mounting Type: Requires Holder (identical)

Allowable Differences:

• Voltage Rating - AC: 600 V (higher than 300 V requirement)
• Voltage Rating - DC: 125 V (higher than 100 V requirement)
• Melting I²t: 5100 (higher than 4800)
• DC Cold Resistance: 0.0024 Ohms (lower than 0.0042 Ohms)

The MDH-21-R-BK operates at higher voltage ratings and maintains identical current and mechanical specifications, making it suitable for applications where the system voltage does not exceed the substitute's ratings.

Parameter Comparison

Engineering Selection Recommendations

Both the Littelfuse 0328021.MXP and Eaton MDH-21-R-BK are active production parts with current inventory availability. Selection between these parts depends on system voltage requirements:

Use Littelfuse 0328021.MXP when:

• System voltage is limited to 300 V AC / 100 V DC maximum
• ROHS3 compliance is specifically required
• UR and TUV certifications are mandated

Use Eaton MDH-21-R-BK when:

• System voltage operates up to 600 V AC / 125 V DC
• cURus certification meets application requirements
• Higher voltage margin is beneficial for system design
• RoHS compliance (non-ROHS3) is acceptable

Both parts share identical current ratings, mechanical dimensions, and holder compatibility, ensuring direct physical and electrical interchangeability within their respective voltage operating ranges.

Frequently Asked Questions (FAQ)

Q: Can the Eaton MDH-21-R-BK replace the Littelfuse 0328021.MXP in all applications?

A: The Eaton substitute is compatible only when system voltage does not exceed 600 V AC and 125 V DC. If your application operates at or below 300 V AC and 100 V DC, both parts are interchangeable. If your system requires higher voltage operation, the Eaton part provides additional margin.

Q: Are the physical dimensions identical between these two fuses?

A: Yes. Both parts use the 3AB, 3AG package configuration with 0.250" diameter and 1.250" length (6.35mm x 31.75mm). They are mechanically interchangeable in standard fuse holders.

Q: What is the significance of the different Melting I²t values?

A: The Melting I²t (4800 for Littelfuse, 5100 for Eaton) indicates the thermal energy required to melt the fuse element. The higher value in the Eaton part reflects its higher voltage rating but does not affect 21 A current protection performance.

Q: Do these fuses require a specific holder type?

A: Both fuses require a holder compatible with 3AB or 3AG cartridge fuse standards. They cannot be used in applications without a proper fuse holder assembly.

Q: Which certifications should I prioritize for my application?

A: Select based on your regional and industry requirements. The Littelfuse part carries UR and TUV approvals; the Eaton part carries cURus approval. Verify that the selected certification meets your application's compliance standards.