Littelfuse 0673.200DRT4 Equivalent & Substitute Parts

Part Overview

The Littelfuse 0673.200DRT4 is a 200 mA, 250 V AC/DC slow-blow glass cartridge fuse with axial through-hole mounting. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system maintenance and new design implementations. Substitute parts must maintain identical electrical ratings and mechanical compatibility to ensure proper circuit protection without redesign.

Key Parameters

Parameter	Value
Current Rating	200 mA
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Mounting Type	Through Hole
Package Type	Cartridge, Non-Standard (Axial)
Breaking Capacity @ Rated Voltage	50 A
Approval Agencies	CSA, UL

Substitute Part Grouping Explanation

Substitution eligibility for the 0673.200DRT4 is determined by the following critical parameters:

Current Rating: 200 mA (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Breaking Capacity: 50 A @ rated voltage (exact match required)
Mounting Type: Through Hole, axial configuration (exact match required)
Approval Certifications: CSA and/or UL compliance (required for safety-critical applications)

The Littelfuse 0875.200MRET1P qualifies as a manufacturer-recommended substitute because it maintains all critical electrical parameters (200 mA, 250 V, slow-blow response, 50 A breaking capacity) and through-hole axial mounting. The primary difference is the fuse element material (ceramic versus glass) and updated product status (active versus obsolete), with enhanced compliance certifications.

Parameter Comparison

Parameter	0673.200DRT4 (Main Part)	0875.200MRET1P (Substitute)
Manufacturer	Littelfuse Inc.	Littelfuse Inc.
Current Rating	200 mA	200 mA
Voltage Rating (AC)	250 V	250 V
Response Time	Slow Blow	Slow Blow
Fuse Type	Cartridge, Glass	Cartridge, Ceramic
Mounting Type	Through Hole	Through Hole
Package / Case	Cartridge, Non-Standard (Axial)	Cartridge, Non-Standard (Axial)
Breaking Capacity @ Rated Voltage	50 A	50 A
Melting I²t	0.0161	0.0165
DC Cold Resistance	2.528 Ohms	0.92 Ohms
Product Status	Obsolete	Active
Approval Agencies	CSA, UL	cULus
RoHS Status	RoHS non-compliant	ROHS3 Compliant
Operating Temperature Range	Not specified	-55°C ~ 125°C
Size / Dimension	0.154" Dia x 0.433" L (3.90mm x 11.00mm)	0.142" Dia x 0.394" L (3.60mm x 10.00mm)

Engineering Selection Recommendations

The Littelfuse 0875.200MRET1P is the manufacturer-recommended substitute for the obsolete 0673.200DRT4. Both components satisfy identical electrical protection requirements with matching current, voltage, and breaking capacity specifications.

Selection considerations based on provided specifications:

The 0875.200MRET1P offers active product status with current manufacturing support, eliminating supply chain risk associated with obsolete components. The substitute maintains cULus certification, which encompasses both CSA and UL approval requirements. ROHS3 compliance of the substitute aligns with modern environmental and regulatory standards, whereas the original part does not meet RoHS requirements.

Physical dimensions differ slightly (0.142" Dia x 0.394" L versus 0.154" Dia x 0.433" L). Verify mechanical fit within the target application's fuse holder or socket before implementation.

DC cold resistance differs between the parts (0.92 Ohms versus 2.528 Ohms). This parameter may affect circuit behavior during cold-start conditions in applications with tight resistance tolerances. Evaluate circuit design sensitivity to this variance.

Frequently Asked Questions (FAQ)

Q: Can the 0875.200MRET1P be used as a direct replacement for the 0673.200DRT4?

A: Yes, the 0875.200MRET1P is the manufacturer-recommended substitute. Both parts maintain identical electrical ratings (200 mA, 250 V, slow-blow response, 50 A breaking capacity) and through-hole axial mounting. Verify mechanical fit in the existing fuse holder, as physical dimensions differ slightly.

Q: What is the primary difference between these two fuses?

A: The main difference is the fuse element material: the 0673.200DRT4 uses glass, while the 0875.200MRET1P uses ceramic. Both materials provide equivalent electrical protection at the specified ratings. The ceramic variant offers active product status, improved compliance certifications (cULus, ROHS3), and lower DC cold resistance.

Q: Why is the 0673.200DRT4 listed as obsolete?

A: Littelfuse has discontinued the 0673.200DRT4 in favor of the 0875.200MRET1P ceramic cartridge fuse, which provides equivalent functionality with enhanced compliance and active manufacturing support.

Q: Are there any compatibility concerns with the dimensional differences?

A: The substitute is slightly smaller (0.142" Dia x 0.394" L) compared to the original (0.154" Dia x 0.433" L). Confirm that the fuse holder or socket accommodates the smaller cartridge. Most standard axial fuse holders accept both sizes, but application-specific holders may require verification.

Q: Does the DC cold resistance difference affect circuit operation?

A: The 0875.200MRET1P has lower DC cold resistance (0.92 Ohms versus 2.528 Ohms). In applications where fuse resistance contributes significantly to circuit behavior during startup or low-temperature operation, evaluate whether this difference impacts performance. For most standard circuit protection applications, this variance is negligible.

Q: What certifications does the substitute part carry?

A: The 0875.200MRET1P carries cULus certification, which satisfies both CSA and UL approval requirements. It also meets ROHS3 compliance standards, whereas the original part does not.

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