MRT 400-AMMO Equivalent & Substitute Parts

Part Overview

The MRT 400-AMMO is a 400 mA, 250 V AC/DC board mount fuse manufactured by Bel Fuse Inc. in radial, can, vertical configuration for through-hole mounting. The part is active in production with 855 units in current inventory. Substitute parts are identified when equivalent electrical ratings, mechanical dimensions, and functional characteristics align within specified tolerances, enabling direct replacement in circuit board applications without design modification.

Substiute Parts

MRT 400-AMMO

Bel Fuse Inc.In Stock: 904MRT 400-AMMO Datasheet

Current PartRFQ

37204000001

Littelfuse Inc.In Stock: 199537204000001 Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MRT 400-AMMO is determined by the following critical parameters:

• Current Rating: Must be 400 mA
• Voltage Rating (AC): Must be 250 V
• Response Time: Must be Slow Blow
• Mounting Type: Must be Through Hole
• Package / Case: Must be Radial, Can, Vertical configuration
• Fuse Type: Must be Board Mount (Cartridge Style Excluded)

The substitute part 37204000001 (Littelfuse Inc., TR5® 372 series) meets all critical electrical and mechanical parameters. Physical dimensions and resistance characteristics fall within acceptable tolerances for direct board-level replacement.

Parameter Comparison

Engineering Selection Recommendations

Both the MRT 400-AMMO and 37204000001 are active production parts with ROHS3 compliance. The MRT 400-AMMO carries broader regulatory approvals (AEC-Q200, CCC, CE, CSA, cURus, SEMKO, VDE) compared to the Littelfuse substitute (CCC, cURus, SEMKO, VDE). Selection between these parts depends on specific application certification requirements and operating environment constraints. The MRT 400-AMMO supports extended temperature operation (-55°C ~ 125°C) versus the Littelfuse part (-40°C ~ 85°C). The MRT 400-AMMO provides higher breaking capacity (50A vs. 35A) and lower melting I²t (1 vs. 1.408). Physical dimensions differ slightly; verify PCB footprint compatibility before substitution.

Frequently Asked Questions (FAQ)

Q: Can 37204000001 directly replace MRT 400-AMMO in all applications?

A: Both parts share identical current rating (400 mA), voltage rating (250 V AC), response time (Slow Blow), mounting type (Through Hole), and package configuration (Radial, Can, Vertical). Direct replacement is possible where operating temperature range (-40°C ~ 85°C for 37204000001 vs. -55°C ~ 125°C for MRT 400-AMMO) and breaking capacity requirements (35A vs. 50A) are compatible with application specifications.

Q: What are the physical dimension differences?

A: MRT 400-AMMO measures 0.329" Dia x 0.303" H (8.35mm x 7.70mm). The 37204000001 measures 0.335" Dia x 0.315" H (8.50mm x 8.00mm). Verify PCB hole spacing and clearance before substitution.

Q: Are there regulatory compliance differences?

A: The MRT 400-AMMO carries AEC-Q200 certification in addition to CCC, CE, CSA, cURus, SEMKO, and VDE. The 37204000001 carries CCC, cURus, SEMKO, and VDE. Applications requiring AEC-Q200 approval must use the MRT 400-AMMO.

Q: What is the difference in DC cold resistance?

A: MRT 400-AMMO has 0.25 Ohms; 37204000001 has 0.205 Ohms. This difference may affect circuit behavior in low-resistance applications.

Q: Which part has better performance in extreme temperature environments?

A: The MRT 400-AMMO operates across -55°C ~ 125°C, providing wider temperature coverage than the 37204000001 (-40°C ~ 85°C). For applications requiring extended low-temperature or high-temperature operation, the MRT 400-AMMO is the appropriate selection.