MDQ-1/2 Equivalent & Substitute Parts Reference

Part Overview

The Eaton MDQ-1/2 is a 500 mA, 250 V AC/DC glass cartridge fuse with slow-blow response characteristics. This fuse is designed for 3AB and 3AG holder compatibility with physical dimensions of 0.250" diameter by 1.250" length (6.35 mm × 31.75 mm). The part maintains Active product status with 633 pieces currently in stock. Equivalent and substitute parts are identified to support procurement flexibility, supply chain continuity, and application-specific compliance requirements.

Key Parameters

Parameter	Value
Current Rating	500 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" × 1-1/4"
Physical Dimensions	0.250" Dia × 1.250" L (6.35 mm × 31.75 mm)
Breaking Capacity @ Rated Voltage	35 A
Mounting Type	Requires Holder
Approval Agencies	CSA, UL

Substitute Part Grouping Explanation

Substitution eligibility for the MDQ-1/2 is determined by strict equivalence across the following critical parameters:

Current Rating: 500 mA (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 3AB, 3AG, 1/4" × 1-1/4" (exact match required)
Physical Dimensions: 0.250" Dia × 1.250" L (exact match required)
Breaking Capacity @ Rated Voltage: 35 A (exact match required)

All identified substitute parts meet these criteria. Variations in secondary parameters such as DC Cold Resistance, Melting I²t, RoHS compliance status, and operating temperature ranges do not disqualify substitution but are documented for application-specific selection.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Current Rating (Amps)	Voltage Rating (AC)	Response Time	Package / Case	Breaking Capacity @ Rated Voltage	DC Cold Resistance (Ohms)	Approval Agency	Inventory (Pcs)
MDQ-1/2	Eaton - Electronics Division	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	1.4	CSA, UL	633
BK/MDL-1/2-R	Eaton - Electronics Division	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	0.943	CE, CSA, UL	1130
BK/MDQ-1/2	Eaton - Electronics Division	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	1.4	CSA, UL	773
MDL-1/2-R	Eaton - Electronics Division	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	0.943	CE, CSA, UL	1068
0313.500HXIDP	Littelfuse Inc.	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	1.26	CE, CSA, UL	781
0313.500HXP	Littelfuse Inc.	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	1.26	CE, CSA, UL	2295
0313.500MXP	Littelfuse Inc.	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	1.26	CE, CSA, UL	4917
0313.500VXP	Littelfuse Inc.	500 mA	250 V	Slow Blow	3AB, 3AG, 1/4" × 1-1/4"	35 A	1.26	CE, CSA, UL	976

Engineering Selection Recommendations

Eaton MDQ Series (MDQ-1/2, BK/MDQ-1/2): These parts maintain identical electrical and mechanical specifications to the reference MDQ-1/2. Selection is appropriate for direct replacement in existing designs. The BK/MDQ-1/2 variant offers higher inventory availability (773 pcs) compared to the base MDQ-1/2 (633 pcs).

Eaton MDL Series (MDL-1/2-R, BK/MDL-1/2-R): These parts provide equivalent functionality with expanded approval agency coverage (CE, CSA, UL versus CSA, UL). The MDL-1/2-R carries RoHS Compliance status, making it suitable for applications with RoHS requirements. DC Cold Resistance is lower (0.943 Ohms versus 1.4 Ohms), which may be advantageous in low-resistance circuit applications. Inventory availability is higher (1068 pcs for MDL-1/2-R, 1130 pcs for BK/MDL-1/2-R).

Littelfuse 313 Series (0313.500HXIDP, 0313.500HXP, 0313.500MXP, 0313.500VXP): All Littelfuse variants meet electrical and mechanical equivalence requirements. These parts feature ROHS3 Compliance and extended operating temperature range (-55°C to 125°C). DC Cold Resistance is 1.26 Ohms. The 0313.500MXP variant offers the highest inventory level (4917 pcs), followed by 0313.500HXP (2295 pcs). Selection among Littelfuse variants should be based on specific application requirements and supply chain preferences.

Frequently Asked Questions (FAQ)

Q: Can the MDQ-1/2 be directly replaced with any of the listed substitute parts?

A: Yes. All listed substitute parts meet the critical electrical and mechanical parameters: 500 mA current rating, 250 V AC voltage rating, slow-blow response, 3AB/3AG package compatibility, and 35 A breaking capacity. Physical dimensions are identical across all parts.

Q: What is the difference between Eaton MDQ and MDL series fuses?

A: Both series meet the same electrical and mechanical specifications for the 500 mA, 250 V application. The MDL series includes CE approval in addition to CSA and UL, and the MDL-1/2-R variant is RoHS Compliant. DC Cold Resistance differs: MDQ series is 1.4 Ohms, while MDL series is 0.943 Ohms.

Q: Are Littelfuse 313 series fuses compatible with Eaton MDQ holders?

A: Yes. The Littelfuse 0313.500 variants share identical physical dimensions (0.250" Dia × 1.250" L) and are designed for 3AB and 3AG holder compatibility. All electrical parameters match the MDQ-1/2 specification.

Q: What is the significance of DC Cold Resistance variation among substitute parts?

A: DC Cold Resistance values range from 0.943 Ohms (Eaton MDL series) to 1.4 Ohms (Eaton MDQ series) to 1.26 Ohms (Littelfuse 313 series). This parameter affects heat dissipation characteristics in the fuse element. Selection should consider circuit design requirements, but all values are within the acceptable range for this fuse category.

Q: Which substitute part offers the best inventory availability?

A: The Littelfuse 0313.500MXP provides the highest inventory level at 4917 pieces, followed by 0313.500HXP at 2295 pieces. Among Eaton parts, BK/MDL-1/2-R offers 1130 pieces.

Q: Do all substitute parts carry the same regulatory approvals?

A: Eaton MDQ-1/2 and BK/MDQ-1/2 carry CSA and UL approvals. Eaton MDL-1/2-R and BK/MDL-1/2-R carry CE, CSA, and UL approvals. All Littelfuse 313 series variants carry CE, CSA, and UL approvals. Applications requiring CE certification should select MDL series or Littelfuse variants.

Q: Are there RoHS compliance differences among the substitute parts?

A: Yes. Eaton MDL-1/2-R is RoHS Compliant. All Littelfuse 313 series variants are ROHS3 Compliant. Eaton MDQ-1/2 and BK/MDQ-1/2 are RoHS non-compliant. Applications with RoHS requirements should select MDL-1/2-R or any Littelfuse variant.

Q: What is the operating temperature range for each substitute part?

A: Eaton MDQ and MDL series do not specify an operating temperature range in the provided data. Littelfuse 313 series variants specify -55°C to 125°C operating temperature range. Applications requiring extended temperature operation should select Littelfuse variants.

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