MRPR-3-12-18 Equivalent & Substitute Parts

Part Overview

The MRPR-3-12-18 is a glass body reed switch manufactured by Littelfuse Inc., configured as a SPST-NO (Single Pole Single Throw - Normally Open) device. This component operates within a 12 to 18 AT (Ampere-Turn) range and is rated for 50W power dissipation with switching capabilities of 1.1A AC and 1.5A DC at 140V AC / 200V DC. The part features through-hole axial termination and operates across a temperature range of -40°C to 125°C.

The MRPR-3-12-18 is classified as obsolete. Identifying equivalent substitute parts is necessary to maintain design continuity, ensure supply chain availability, and support ongoing production or maintenance requirements for applications utilizing this component.

Substiute Parts

MRPR-3-12-18

Littelfuse Inc.In Stock: 878MRPR-3-12-18 Datasheet

Current PartRFQ

MRPR-20-12-18

Littelfuse Inc.In Stock: 749MRPR-20-12-18 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the MRPR-3-12-18 is determined by the following critical parameters that must remain equivalent or superior:

• Circuit configuration (SPST-NO)
• Operate range (12 ~ 18 AT)
• Current switching capability (1.1A AC minimum, 1.5A DC minimum)
• Voltage switching capability (140V AC minimum, 200V DC minimum)
• Power rating (50W minimum)
• Mounting type (Through Hole)
• Termination style (Axial)
• Operating temperature range (must encompass or exceed -40°C ~ 125°C)
• RoHS compliance status

The MRPR-20-12-18 qualifies as a direct substitute. It maintains identical circuit configuration, operate range, current switching ratings, power rating, mounting type, and termination style. The substitute part exceeds the voltage switching specifications (265V AC / 250V DC versus 140V AC / 200V DC), providing enhanced voltage margin. Both parts are ROHS3 compliant and feature identical physical dimensions and electrical characteristics except for voltage rating and operating temperature lower bound.

Parameter Comparison

Engineering Selection Recommendations

The MRPR-20-12-18 is the appropriate substitute for the obsolete MRPR-3-12-18 based on the following factors:

Electrical Equivalence: The substitute part maintains all critical switching parameters including circuit configuration, operate range, current ratings, and power dissipation. The elevated voltage switching ratings (265V AC / 250V DC) provide additional design margin compared to the original specification (140V AC / 200V DC).

Mechanical Compatibility: Both parts share identical mounting type (through-hole), termination style (axial), and overall length. Body diameter remains constant at 0.112" (2.84mm). The body length difference of 0.025" (0.63mm) is negligible for through-hole applications.

Compliance and Availability: The MRPR-20-12-18 is ROHS3 compliant and maintains active product status with documented inventory availability. The original MRPR-3-12-18 is obsolete and no longer manufactured.

Temperature Consideration: The substitute part operates from -20°C to 125°C, compared to the original -40°C to 125°C range. Applications requiring operation below -20°C require evaluation against the substitute's lower temperature bound.

Frequently Asked Questions (FAQ)

Q: Can the MRPR-20-12-18 directly replace the MRPR-3-12-18 in existing designs?

A: Yes, for applications operating at or above -20°C. The substitute maintains identical circuit configuration, current switching ratings, power rating, and physical mounting characteristics. The higher voltage rating provides additional margin. Applications requiring operation below -20°C require thermal analysis against the substitute's lower temperature specification.

Q: What is the significance of the voltage rating difference?

A: The MRPR-20-12-18 is rated for 265V AC and 250V DC switching, compared to the original 140V AC and 200V DC. This represents a voltage margin increase. The substitute is suitable for applications originally designed for the lower voltage specification and provides enhanced performance headroom for higher voltage applications within the substitute's rating.

Q: Are the physical dimensions compatible with existing PCB layouts?

A: Yes. Both parts feature identical overall length (2.230" / 56.64mm), identical body diameter (0.112" / 2.84mm), and axial termination. The body length difference of 0.025" (0.63mm) does not affect through-hole mounting compatibility or PCB footprint requirements.

Q: What is the impact of the operating temperature range difference?

A: The substitute operates from -20°C to 125°C, while the original operates from -40°C to 125°C. For applications requiring operation below -20°C, the substitute's lower temperature bound must be evaluated against actual operating conditions. Applications within the -20°C to 125°C range experience no functional limitation.

Q: Is the MRPR-20-12-18 RoHS compliant?

A: Yes. The MRPR-20-12-18 is ROHS3 compliant, matching the compliance status of the original MRPR-3-12-18.

Q: Why is the original part obsolete?

A: The MRPR-3-12-18 is classified as obsolete by Littelfuse Inc. The MRPR-20-12-18 represents the current active product line for equivalent SPST-NO reed switch functionality within this operating range and voltage class.