MDRR-DT-35-40-F Equivalent & Substitute Parts

Part Overview

The MDRR-DT-35-40-F is a glass body reed switch manufactured by Littelfuse Inc., configured as a single-pole double-throw (SPDT) contact arrangement. This component is rated for 180mA AC switching at 120V and 250mA DC switching at 175V, with a 5W power rating and 35–40AT operate range. The part is currently listed as obsolete, necessitating identification of functionally equivalent alternatives for ongoing system support and new designs.

Substiute Parts

MDRR-DT-35-40-F

Littelfuse Inc.In Stock: 984MDRR-DT-35-40-F Datasheet

Current PartRFQ

MDRR-DT-30-40-F

Littelfuse Inc.In Stock: 855MDRR-DT-30-40-F Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MDRR-DT-35-40-F is determined by the following critical parameters:

• Circuit Configuration: Must be SPDT to maintain contact switching logic
• Current Rating: Must support minimum 180mA AC and 250mA DC switching capacity
• Voltage Rating: Must support minimum 120V AC and 175V DC switching
• Power Rating: Must support minimum 5W dissipation
• Mounting and Termination: Must be through-hole with axial termination for mechanical compatibility
• Operating Temperature: Must cover -40°C to 125°C range
• Operate Range: Must be compatible with the magnetic field requirements of the application

The MDRR-DT-30-40-F qualifies as a direct substitute. While its operate range is specified as 30–40AT (versus 35–40AT for the main part), all other electrical, mechanical, and environmental parameters are identical. The broader operate range of the substitute part ensures compatibility with applications designed for the original component.

Parameter Comparison

Engineering Selection Recommendations

The MDRR-DT-30-40-F is the recommended substitute for the obsolete MDRR-DT-35-40-F. Both components are manufactured by Littelfuse Inc. within the same MDRR-DT series and share identical electrical specifications, mechanical dimensions, and environmental ratings. The substitute part maintains active product status, ensuring continued availability and supply chain support.

Both parts carry ROHS3 compliance and REACH unaffected status, meeting current regulatory requirements. The substitute's broader operate range (30–40AT) encompasses the original part's specification window (35–40AT), confirming functional compatibility for all applications designed around the main part.

Frequently Asked Questions (FAQ)

Q: Can the MDRR-DT-30-40-F directly replace the MDRR-DT-35-40-F in existing designs?

A: Yes. The substitute part maintains identical electrical ratings (180mA AC, 250mA DC, 120V AC, 175V DC, 5W), mechanical form factor (through-hole axial termination, 51.66mm length), and environmental specifications (-40°C to 125°C). The broader operate range of the substitute ensures compatibility.

Q: What is the significance of the operate range difference (35–40AT vs. 30–40AT)?

A: Operate range defines the magnetic field strength (in Ampere-Turns) required to close the reed switch contacts. The substitute's 30–40AT range encompasses the original 35–40AT specification, meaning it will activate within or below the original activation threshold, maintaining functional compatibility.

Q: Are there any compliance or certification differences between the two parts?

A: No. Both parts are ROHS3 compliant, REACH unaffected, and carry identical moisture sensitivity ratings (MSL 1, Unlimited). Regulatory and environmental compliance are equivalent.

Q: Why is the original part listed as obsolete?

A: The MDRR-DT-35-40-F is obsolete due to manufacturer discontinuation. The MDRR-DT-30-40-F remains in active production and serves the same functional requirements.

Q: Are the physical dimensions identical?

A: Yes. Both parts measure 2.034" (51.66mm) overall length with a 0.100" diameter × 0.580" length body (2.54mm × 14.73mm). PCB footprints and mounting hole spacing are identical.