MQ 5TR Equivalent & Substitute Parts

Part Overview

The MQ 5TR is a 5A 125VAC/VDC board mount axial fuse manufactured by Bel Fuse Inc. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and component procurement. The MQ 5TR serves as a fast-blow protective device in through-hole applications requiring 5 ampere current limiting at 125 volt AC and DC ratings.

Substiute Parts

MQ 5TR

Bel Fuse Inc.In Stock: 1110MQ 5TR Datasheet

Current PartRFQ

0251005.NRT1L

Littelfuse Inc.In Stock: 1850960251005.NRT1L Datasheet

DirectRFQ

0251005.MXL

Littelfuse Inc.In Stock: 90500251005.MXL Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the MQ 5TR are qualified based on strict electrical and mechanical parameter matching:

Critical Matching Parameters:

• Current Rating: 5 A (exact match required)
• Voltage Rating - AC: 125 V (exact match required)
• Voltage Rating - DC: 125 V (exact match required)
• Response Time: Fast Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Fuse Type: Board Mount (Cartridge Style Excluded) (exact match required)
• Package / Case: Axial (exact match required)
• Breaking Capacity @ Rated Voltage: 50A AC, 300A DC (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (exact match required)

Both substitute parts listed below meet all critical electrical and mechanical parameters. Differences in physical dimensions (diameter and length) and DC cold resistance remain within acceptable tolerances for board mount axial fuse applications. The substitute parts are manufactured by Littelfuse Inc. under the PICO® II 251 series and maintain active product status with enhanced compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

Both Littelfuse PICO® II 251 series fuses (0251005.NRT1L and 0251005.MXL) are direct functional equivalents to the obsolete MQ 5TR. Selection between these two substitute parts is determined by packaging requirements:

0251005.NRT1L is supplied in Cut Tape (CT) packaging with 185,000 pieces in stock inventory, suitable for automated assembly processes and high-volume production environments.

0251005.MXL is supplied in Bulk packaging with 9,015 pieces in stock inventory, suitable for manual assembly and lower-volume applications.

Both substitute parts maintain active product status and provide enhanced compliance certifications (CCC, CSA, cURus, PSE, TUV) compared to the original MQ 5TR. The Littelfuse alternatives are ROHS3 compliant, supporting modern regulatory requirements. Physical dimension differences (reduced diameter from 3.18mm to 2.80mm) are compatible with standard through-hole board mount applications. The slightly higher melting I²t value (4.14 versus 3.4) represents improved thermal performance within the fast-blow response classification.

Frequently Asked Questions (FAQ)

Q: Can 0251005.NRT1L and 0251005.MXL be used interchangeably with MQ 5TR?

A: Yes. Both Littelfuse parts meet all critical electrical parameters: 5A current rating, 125VAC/VDC voltage rating, fast-blow response, through-hole mounting, and 50A AC / 300A DC breaking capacity. The difference between these two substitute parts is packaging format only (Cut Tape versus Bulk).

Q: What is the significance of the melting I²t difference between MQ 5TR (3.4) and the Littelfuse substitutes (4.14)?

A: The melting I²t value characterizes thermal energy absorption before fuse element melting. The higher value in Littelfuse parts indicates slightly improved thermal performance while maintaining fast-blow response classification. This difference does not affect functional compatibility in standard 5A 125V applications.

Q: Are the physical dimension changes from 3.18mm to 2.80mm diameter compatible with existing PCB designs?

A: Yes. The reduced diameter of the Littelfuse substitutes is compatible with standard through-hole board mount fuse footprints. The axial length remains essentially identical (7.10mm versus 7.11mm). Verification of PCB hole sizing is recommended for legacy designs with tight mechanical tolerances.

Q: What compliance advantages do the Littelfuse substitutes provide?

A: The Littelfuse PICO® II 251 series parts carry expanded approval certifications (CCC, CSA, cURus, PSE, TUV) and ROHS3 compliance status, compared to the MQ 5TR certifications (CE, CSA, cURus). This provides broader regulatory acceptance in international markets and modern supply chain requirements.

Q: Which substitute part should be selected for new designs?

A: For new designs, either 0251005.NRT1L or 0251005.MXL is appropriate based on assembly process requirements. Cut Tape (0251005.NRT1L) is preferred for automated assembly; Bulk (0251005.MXL) is suitable for manual assembly or lower-volume production.