MQ 2 Equivalent & Substitute Parts

Part Overview

The MQ 2 is a 2A 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 2 serves as a fast-blow protection device in through-hole applications requiring 125V AC/DC rated protection at 2A current levels.

Key Parameters

Parameter	Value
Current Rating	2 A
Voltage Rating - AC	125 V
Voltage Rating - DC	125 V
Response Time	Fast Blow
Mounting Type	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)
Package / Case	Axial
Breaking Capacity @ Rated Voltage	50A AC, 300A DC
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitute parts for the MQ 2 are qualified based on the following electrical and mechanical parameters:

Current Rating: 2 A (exact match required)
Voltage Rating: 125 V AC and 125 V DC (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)
Operating Temperature Range: Minimum -55°C to maximum 125°C (substitute must meet or exceed)
Breaking Capacity: Minimum 50A AC and 300A DC (substitute must meet or exceed)

The substitute parts listed below satisfy all mandatory electrical parameters. Physical dimensions may vary within acceptable PCB assembly tolerances. Packaging format differences (Bulk vs. Cut Tape) do not affect electrical equivalency.

Parameter Comparison

Parameter	MQ 2 (Bel Fuse)	0251002.MXL (Littelfuse)	0251002.NRT1L (Littelfuse)	7010.7090.13 (SCHURTER)
Manufacturer	Bel Fuse Inc.	Littelfuse Inc.	Littelfuse Inc.	SCHURTER Inc.
Current Rating (Amps)	2 A	2 A	2 A	2 A
Voltage Rating - AC	125 V	125 V	125 V	125 V
Voltage Rating - DC	125 V	125 V	125 V	125 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Axial	Axial	Axial	Cartridge, Non-Standard (Axial)
Breaking Capacity @ Rated Voltage	50A AC, 300A DC	50A AC, 300A DC	50A AC, 300A DC	300A
Operating Temperature Range	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 85°C
Product Status	Obsolete	Active	Active	Active
DC Cold Resistance (Ohms)	0.055	0.0473	0.0473	Not specified
Melting I²t	0.33	0.405	0.405	1.1

Engineering Selection Recommendations

All three substitute parts meet the mandatory electrical specifications for 2A 125VAC/VDC fast-blow protection. Selection should be based on product availability, compliance requirements, and packaging format:

0251002.MXL and 0251002.NRT1L (Littelfuse PICO® II 251 Series): Both parts are electrically identical and differ only in packaging format (Bulk vs. Cut Tape). These parts carry active product status with expanded approval certifications (CCC, CSA, cURus, PSE, TUV) and ROHS3 compliance. The identical melting I²t value (0.405) and DC cold resistance (0.0473 Ohms) provide consistent performance characteristics. Physical dimensions are 0.110" Dia x 0.280" L, slightly smaller than the original MQ 2.

7010.7090.13 (SCHURTER 172322 Series): This part maintains all critical electrical parameters but operates within a reduced temperature range (-55°C ~ 85°C). The melting I²t value (1.1) is higher than the original specification, indicating a slower thermal response. This part carries CSA and UR certifications with ROHS3 compliance. Physical dimensions are 0.093" Dia x 0.315" L. Selection of this part requires verification that the reduced upper operating temperature limit and altered thermal response characteristics are acceptable for the target application.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 0251002.MXL and 0251002.NRT1L be used interchangeably?

A: Yes. Both parts are electrically and functionally identical. The difference is packaging format only: 0251002.MXL is supplied in Bulk packaging, while 0251002.NRT1L is supplied in Cut Tape (CT) format. Selection depends on procurement and assembly process requirements.

Q: What is the impact of the different melting I²t values?

A: The melting I²t parameter defines the thermal energy required to melt the fuse element. The MQ 2 has a melting I²t of 0.33, while the Littelfuse substitutes have 0.405, and the SCHURTER part has 1.1. Higher values indicate slower thermal response. The Littelfuse parts (0.405) provide closer thermal characteristics to the original. The SCHURTER part (1.1) represents a significant deviation and may alter circuit protection timing.

Q: Are there physical dimension compatibility concerns?

A: The MQ 2 measures 0.125" Dia x 0.280" L. The Littelfuse substitutes measure 0.110" Dia x 0.280" L (slightly smaller diameter). The SCHURTER part measures 0.093" Dia x 0.315" L (smaller diameter, slightly longer). These dimensional differences are within typical PCB assembly tolerances for through-hole axial components. Verify mechanical fit within the target PCB footprint before production implementation.

Q: Does the SCHURTER part's reduced operating temperature range affect suitability?

A: The SCHURTER 7010.7090.13 operates to 85°C maximum, compared to 125°C for the original MQ 2 and Littelfuse substitutes. If the application requires operation above 85°C, this part is not suitable. Verify the maximum ambient and component operating temperatures in the target application.

Q: Which substitute part offers the best compliance coverage?

A: The Littelfuse PICO® II 251 series (both 0251002.MXL and 0251002.NRT1L) carry the broadest approval certifications: CCC, CSA, cURus, PSE, and TUV, with ROHS3 compliance. The SCHURTER part carries CSA and UR certifications with ROHS3 compliance. Selection should align with the specific regulatory requirements of the target application and end market.

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