MLRR-3-12-18 Equivalent & Substitute Parts

Part Overview

The MLRR-3-12-18 is a glass body reed switch manufactured by Littelfuse, configured as a SPST-NO (Single Pole Single Throw - Normally Open) device. This through-hole mounted component operates within a 12 to 18 AT (Ampere-Turn) range and is rated for 700mA AC or 1A DC switching at 140V AC / 200V DC. The part is currently active in production with full RoHS3 compliance and unlimited moisture sensitivity rating. Substitute parts are identified when equivalent electrical performance and mechanical compatibility can be maintained across the specified parameter range.

Substiute Parts

MLRR-3-12-18

LittelfuseIn Stock: 1838MLRR-3-12-18 Datasheet

Current PartRFQ

MLRR-4-12-18

Littelfuse Inc.In Stock: 1943MLRR-4-12-18 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

The MLRR-4-12-18 qualifies as a direct substitute for the MLRR-3-12-18 based on the following critical parameters:

• Circuit Configuration: Both parts are SPST-NO reed switches
• Operate Range: Identical 12 ~ 18 AT specification
• Current Ratings: Both rated for 700 mA AC and 1 A DC switching
• Voltage Ratings: Both rated for 140 V AC and 200 V DC
• Power Rating: Both rated for 20 W
• Mounting and Termination: Both are through-hole mounted with axial termination
• Operating Temperature: Identical -40°C ~ 125°C range
• Compliance: Both RoHS3 compliant with unlimited MSL rating

The primary differences between these parts are confined to non-critical dimensional and timing parameters that do not affect electrical substitutability.

Parameter Comparison

Engineering Selection Recommendations

Both the MLRR-3-12-18 and MLRR-4-12-18 are active production parts with full RoHS3 compliance and REACH unaffected status. Selection between these parts should be based on:

• PCB Space Constraints: The MLRR-4-12-18 has a shorter overall length (1.590" vs 2.230"), making it suitable for applications with limited board real estate.
• Response Time Requirements: The MLRR-4-12-18 offers a faster operate time of 0.6 ms compared to 0.7 ms for the MLRR-3-12-18, where timing-sensitive applications may benefit from this improvement.
• DC Current Carry Capacity: The MLRR-3-12-18 supports 1.2 A DC carry current versus 1 A for the MLRR-4-12-18. Applications requiring maximum DC current handling should specify the MLRR-3-12-18.

Both parts maintain identical electrical performance across all switching parameters and are suitable for direct substitution in standard applications.

Frequently Asked Questions (FAQ)

Q: Can MLRR-4-12-18 be used as a direct replacement for MLRR-3-12-18?

A: Yes. Both parts share identical circuit configuration (SPST-NO), operate range (12 ~ 18 AT), switching current ratings (700 mA AC / 1 A DC), and voltage ratings (140 V AC / 200 V DC). The primary differences are overall length and operate time, which do not affect electrical substitutability in standard applications.

Q: What are the dimensional differences between these parts?

A: The MLRR-3-12-18 has an overall length of 2.230" (56.64 mm), while the MLRR-4-12-18 measures 1.590" (40.39 mm). Both maintain identical body dimensions of 0.105" diameter by 0.600" length. PCB layout and clearance requirements should be verified before substitution.

Q: Are there any compliance or certification differences?

A: No. Both parts are RoHS3 compliant, REACH unaffected, and carry unlimited moisture sensitivity rating (MSL 1). Regulatory and environmental compliance is equivalent.

Q: What is the difference in operate time between these parts?

A: The MLRR-3-12-18 operates in 0.7 ms, while the MLRR-4-12-18 operates in 0.6 ms. Both have identical release time of 0.2 ms. For timing-critical applications, the faster response of the MLRR-4-12-18 may be advantageous.

Q: Which part should I select for maximum DC current handling?

A: The MLRR-3-12-18 supports 1.2 A DC carry current compared to 1 A for the MLRR-4-12-18. If maximum DC current capacity is required, specify the MLRR-3-12-18.