MQ 12TR Equivalent & Substitute Parts

Part Overview

The MQ 12TR is a 12A 125VAC/VDC board mount axial fuse manufactured by Bel Fuse Inc. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement. The MQ 12TR serves as a fast-blow protective device in through-hole applications requiring 125V AC/DC rated protection.

Substiute Parts

MQ 12TR

Bel Fuse Inc.In Stock: 933MQ 12TR Datasheet

Current PartRFQ

0251012.MRT1L

Littelfuse Inc.In Stock: 13190251012.MRT1L Datasheet

SimilarRFQ

0251012.NRT1L

Littelfuse Inc.In Stock: 225990251012.NRT1L Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution for the MQ 12TR is based on the following critical parameters that must remain constant or compatible:

• Current Rating: 12 A (exact match required)
• Mounting Type: Through Hole (exact match required)
• Fuse Type: Board Mount Axial (exact match required)
• Response Time: Fast Blow (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)

The substitute parts identified are from the Littelfuse PICO® II 251 series. These parts maintain identical current ratings, mounting configurations, and response characteristics. However, the voltage rating differs: substitute parts are rated 32VAC/32VDC compared to the original 125VAC/125VDC. This voltage reduction represents a more conservative rating and is acceptable only in applications where the actual circuit voltage does not exceed 32V AC/DC.

Parameter Comparison

Engineering Selection Recommendations

0251012.NRT1L is the primary substitute for the MQ 12TR. This part is active in production with 22,500 units in stock, ensuring long-term availability. It carries CSA and cURus certifications, meeting regulatory requirements for most applications. The ROHS3 compliance status provides environmental compliance advantages over the obsolete original part.

0251012.MRT1L is an alternative substitute with identical electrical characteristics to 0251012.NRT1L but lower inventory availability (1,225 units). Both Littelfuse parts are functionally equivalent for applications operating at 32V AC/DC or below.

Critical Voltage Consideration: The substitute parts carry a 32V AC/DC rating versus the original 125V AC/DC rating. Selection of these substitutes is valid only for circuits where the maximum applied voltage does not exceed 32V AC/DC. For applications requiring the full 125V rating, alternative sources must be evaluated.

Frequently Asked Questions (FAQ)

Q: Can 0251012.NRT1L directly replace MQ 12TR in all applications?

A: Direct replacement is valid only in applications where circuit voltage does not exceed 32V AC/DC. The substitute part has a lower voltage rating (32V) compared to the original (125V). Verify actual circuit voltage before substitution.

Q: What is the difference between 0251012.MRT1L and 0251012.NRT1L?

A: Both parts are electrically identical with matching current ratings, voltage ratings, response times, and breaking capacities. The primary difference is packaging format (both Cut Tape) and inventory availability. 0251012.NRT1L has significantly higher stock levels (22,500 units vs. 1,225 units).

Q: Are there physical dimension differences between the original and substitute parts?

A: Yes. The MQ 12TR has a diameter of 0.125" (3.18mm), while both Littelfuse substitutes have a diameter of 0.110" (2.80mm). The length remains consistent at 0.280" (7.10-7.11mm). Verify PCB pad spacing and through-hole sizing before installation.

Q: What certifications do the substitute parts carry?

A: Both 0251012.MRT1L and 0251012.NRT1L carry CSA and cURus certifications. The original MQ 12TR carried CE, CSA, and cURus certifications. Confirm certification requirements for your specific application.

Q: Is RoHS compliance a factor in selecting substitutes?

A: Yes. Both Littelfuse substitutes are ROHS3 compliant, whereas the original MQ 12TR status is not specified. For applications requiring RoHS compliance, the Littelfuse parts provide documented compliance.