5MF 300-R Equivalent & Substitute Parts

Part Overview

The 5MF 300-R is a 300 mA, 250 V AC/DC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc. in a 5mm x 20mm package format. This component is classified as obsolete, making identification of active equivalent parts essential for ongoing system maintenance and new design implementations. Substitute parts must maintain identical electrical ratings and mechanical compatibility to ensure proper circuit protection without modification to existing fuse holders.

Substiute Parts

5MF 300-R

Bel Fuse Inc.In Stock: 10125MF 300-R Datasheet

Current PartRFQ

0235.300HXP

Littelfuse Inc.In Stock: 10230235.300HXP Datasheet

DirectRFQ

0235.300MXP

Littelfuse Inc.In Stock: 16000235.300MXP Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 5MF 300-R is determined by strict equivalence across the following parameters:

• Current Rating: 300 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Fast Blow (exact match required)
• Package / Case: 5mm x 20mm (exact match required)
• Mounting Type: Requires Holder (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (minimum requirement)

The following parts meet all substitution criteria:

• 0235.300HXP (Littelfuse Inc., Series 235)
• 0235.300MXP (Littelfuse Inc., Series 235)

Parameter Comparison

Engineering Selection Recommendations

Both 0235.300HXP and 0235.300MXP are direct functional equivalents to the 5MF 300-R. Selection between these two Littelfuse alternatives should be based on availability and packaging requirements:

• 0235.300HXP: 944 units in stock, bulk packaging
• 0235.300MXP: 1493 units in stock, bulk packaging

Both parts carry active product status and maintain full compliance with CE, CSA, and UL certifications. The Littelfuse 235 series parts provide superior regulatory coverage compared to the original Bel Fuse component, with the addition of KC approval. Both substitute parts are ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements.

Frequently Asked Questions (FAQ)

Q: Can 0235.300HXP and 0235.300MXP be used interchangeably with the 5MF 300-R?

A: Yes. Both parts are electrically and mechanically equivalent. They share identical current ratings (300 mA), voltage ratings (250 V AC), fuse type (cartridge, glass), response time (fast blow), and package dimensions (5mm x 20mm). Both are compatible with existing 5mm x 20mm fuse holders.

Q: What is the difference between 0235.300HXP and 0235.300MXP?

A: Both parts are functionally identical in electrical and mechanical specifications. The difference lies in packaging designation and inventory availability. 0235.300MXP has higher stock levels (1493 units vs. 944 units).

Q: Why is the 5MF 300-R listed as obsolete?

A: The 5MF 300-R has been discontinued by Bel Fuse Inc. The Littelfuse 235 series equivalents (0235.300HXP and 0235.300MXP) are active products that provide identical functionality with enhanced regulatory certifications.

Q: Are there any dimensional differences between the main part and substitutes?

A: The package case specification is 5mm x 20mm for all parts. Minor dimensional variations exist (5.10mm vs. 5.20mm diameter), but these fall within standard tolerance ranges for 5mm x 20mm cartridge fuses and do not affect holder compatibility.

Q: Do the substitute parts require any circuit modifications?

A: No. The substitute parts are direct replacements requiring no circuit modifications. They are designed for use in existing 5mm x 20mm fuse holders without any adapter or modification.