MLRR-4-12-18 Equivalent & Substitute Parts

Part Overview

The MLRR-4-12-18 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 700mA AC or 1A DC switching at 140V AC / 200V DC, with a maximum power dissipation of 20W. The part is mounted through-hole with axial termination and is currently in active production status with ROHS3 compliance and unlimited moisture sensitivity rating.

Substitute parts are identified when equivalent electrical performance and mechanical compatibility can be maintained across the specified operating parameters, allowing for design flexibility and supply chain optimization.

Substiute Parts

MLRR-4-12-18

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

Current PartRFQ

MLRR-3-12-18

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

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

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

• Circuit Configuration: Both parts are SPST-NO devices with identical switching logic
• Operate Range: Both operate within 12 ~ 18 AT specification
• Switching Current: Both support 700mA AC and 1A DC switching capacity
• Switching Voltage: Both rated for 140V AC and 200V DC
• Power Rating: Both rated at 20W maximum power dissipation
• Mounting and Termination: Both use through-hole mounting with axial termination
• Operating Temperature: Both function across -40°C to 125°C range
• Compliance: Both are ROHS3 compliant with unlimited MSL rating

Differences in overall length (40.39mm vs 56.64mm), operate time (0.6ms vs 0.7ms), release time (0.2ms for both), and DC carry current (1A vs 1.2A) do not prevent substitution when the primary switching parameters remain within specification.

Parameter Comparison

Engineering Selection Recommendations

Both the MLRR-4-12-18 and MLRR-3-12-18 are active production components with identical regulatory compliance profiles. Selection between these parts should be based on:

• PCB Layout Constraints: The MLRR-4-12-18 offers a shorter overall length (40.39mm) compared to the MLRR-3-12-18 (56.64mm), making it suitable for space-constrained applications
• Switching Speed Requirements: The MLRR-4-12-18 provides faster operate time (0.6ms vs 0.7ms), beneficial for time-sensitive switching applications
• DC Current Carrying Capacity: The MLRR-3-12-18 supports higher continuous DC current (1.2A vs 1A), advantageous for sustained load conditions
• Supply Chain Availability: Both parts maintain active inventory status; selection may depend on current stock levels and lead times

All electrical switching parameters remain equivalent across both parts, ensuring functional interchangeability within the specified operating envelope.

Frequently Asked Questions (FAQ)

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

A: Yes. Both parts share identical switching specifications (SPST-NO, 700mA AC / 1A DC, 140V AC / 200V DC, 20W), operate range (12-18 AT), and temperature rating (-40°C to 125°C). The primary design consideration is the difference in overall length: MLRR-4-12-18 measures 40.39mm while MLRR-3-12-18 measures 56.64mm. PCB layout must accommodate the longer component if substituting with MLRR-3-12-18.

Q: What are the key differences between these two parts?

A: The MLRR-4-12-18 and MLRR-3-12-18 differ in three parameters: overall length (40.39mm vs 56.64mm), operate time (0.6ms vs 0.7ms), and DC carry current (1A vs 1.2A). All other electrical and mechanical specifications are identical.

Q: Are there any compliance or certification differences?

A: No. Both parts are ROHS3 compliant, REACH unaffected, carry unlimited moisture sensitivity rating (MSL 1), and maintain active product status. Regulatory compliance is equivalent.

Q: Which part should be selected for space-constrained applications?

A: The MLRR-4-12-18 is recommended for space-constrained designs due to its shorter overall length of 40.39mm compared to the MLRR-3-12-18 at 56.64mm.

Q: Which part is better for applications requiring sustained DC current?

A: The MLRR-3-12-18 supports higher continuous DC carry current (1.2A) compared to the MLRR-4-12-18 (1A), making it suitable for applications with sustained DC load requirements.

Q: Are the switching voltage and current ratings identical?

A: Yes. Both parts are rated for 700mA AC and 1A DC switching current, with 140V AC and 200V DC switching voltage specifications. Maximum power dissipation is 20W for both.