Littelfuse 0429007.WRMLHF Surface Mount Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0429007.WRMLHF is a 7A board mount surface mount fuse rated for 24V AC/DC operation in a 1206 (3216 Metric) package. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing design support and procurement continuity. The fast-blow response characteristic and compact surface mount form factor position this fuse for protection in low-voltage DC and AC circuits requiring rapid fault isolation.

Substiute Parts

0429007.WRMLHF

Littelfuse Inc.In Stock: 602600429007.WRMLHF Datasheet

Current PartRFQ

0437007.WR

Littelfuse Inc.In Stock: 1022160437007.WR Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the obsolete 0429007.WRMLHF is permissible with the Littelfuse 0437007.WR based on the following electrical and mechanical compatibility criteria:

Current Rating: Both parts maintain identical 7A current rating, ensuring equivalent load protection characteristics.

Package / Case: Both parts use the 1206 (3216 Metric) surface mount package, providing mechanical and footprint compatibility on printed circuit boards.

Mounting Type: Both parts are surface mount board mount fuses (cartridge style excluded), allowing direct PCB assembly compatibility.

Response Time: Both parts feature fast-blow response characteristics, maintaining identical fault isolation speed.

Voltage Ratings: The substitute part (0437007.WR) provides higher voltage ratings (32V AC / 35V DC) compared to the original (24V AC / 24V DC). Higher voltage ratings are acceptable in applications operating at or below the original voltage specification, as the substitute will function safely in lower-voltage circuits.

Approval Agencies: Both parts carry CSA and UL certifications, maintaining regulatory compliance standards.

RoHS Compliance: Both parts are ROHS3 compliant, ensuring environmental and regulatory alignment.

Parameter Comparison

Engineering Selection Recommendations

The Littelfuse 0437007.WR is the manufacturer-recommended substitute for the obsolete 0429007.WRMLHF. Selection of this substitute is supported by:

Product Status: The substitute part maintains active production status, ensuring long-term availability and supply chain continuity compared to the obsolete original part.

Regulatory Compliance: Both parts maintain CSA and UL certifications, with the substitute offering ROHS3 compliance identical to the original.

Electrical Compatibility: The substitute part's higher voltage ratings (32V AC / 35V DC) provide enhanced margin for applications operating at the original 24V specification. The identical 7A current rating ensures protection characteristics remain unchanged.

Mechanical Compatibility: Identical 1206 package dimensions and surface mount configuration enable direct board-level substitution without design modification.

Enhanced Performance Characteristics: The substitute part provides increased breaking capacity (50A vs. 35A) and extended operating temperature range (-55°C to 150°C vs. -55°C to 90°C), offering improved performance margins in demanding applications.

Frequently Asked Questions (FAQ)

Q: Can the 0437007.WR substitute directly replace the 0429007.WRMLHF on existing PCBs?

A: Yes. Both parts use identical 1206 (3216 Metric) surface mount packages with matching footprints, enabling direct PCB substitution without layout modification.

Q: Why does the substitute part have higher voltage ratings?

A: The 0437007.WR is rated for 32V AC and 35V DC, compared to the original 24V AC/DC rating. Higher voltage ratings do not affect operation in lower-voltage circuits. The substitute will function safely in any application operating at or below 24V AC/DC.

Q: Are there differences in current protection characteristics?

A: No. Both parts maintain identical 7A current ratings and fast-blow response times, providing equivalent fault protection behavior.

Q: What is the significance of the higher breaking capacity in the substitute part?

A: The substitute part's 50A breaking capacity (vs. 35A in the original) indicates enhanced ability to safely interrupt higher fault currents. This provides additional safety margin without affecting normal circuit operation.

Q: Does the extended operating temperature range of the substitute affect compatibility?

A: No. The substitute's -55°C to 150°C operating range encompasses the original part's -55°C to 90°C range. Applications operating within the original temperature specification will function identically.

Q: Are both parts RoHS compliant?

A: Yes. Both the original and substitute parts are ROHS3 compliant, meeting environmental and regulatory requirements.

Q: What is the difference in DC cold resistance between the two parts?

A: The original part has 0.00925 Ohms resistance, while the substitute has 0.01 Ohms. This minimal difference (approximately 8%) has negligible impact on circuit performance in typical applications.

Q: Is the substitute part available in the same packaging format?

A: The original part is supplied in standard packaging, while the substitute (0437007.WR) is available in Tape & Reel (TR) format. Both formats are suitable for automated PCB assembly processes.