MICROSMD400LR-2 Equivalent & Substitute Parts

Part Overview

The MICROSMD400LR-2 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 6V at 4A hold current in a 1210 (3225 Metric) surface mount package. This component is classified as obsolete, making equivalent substitute parts necessary for new designs and ongoing production requirements. The part operates across a temperature range of -40°C to 80°C and complies with ROHS3 standards.

Substiute Parts

MICROSMD400LR-2

Littelfuse Inc.In Stock: 780MICROSMD400LR-2 Datasheet

Current PartRFQ

1210L400SLWR

Littelfuse Inc.In Stock: 419331210L400SLWR Datasheet

MFR RecommendedRFQ

PTSLR12106V400

Eaton - Electronics DivisionIn Stock: 6507PTSLR12106V400 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MICROSMD400LR-2 is determined by the following critical parameters:

• Voltage rating must equal or exceed 6V maximum
• Current hold (Ih) rating must equal or exceed 4A
• Package must be 1210 (3225 Metric) surface mount
• Mounting type must be surface mount
• RoHS compliance status must meet or exceed ROHS3

Both substitute parts meet these core electrical and mechanical requirements. The 1210L400SLWR and PTSLR12106V400 are functionally equivalent alternatives with active product status, providing improved availability compared to the obsolete MICROSMD400LR-2.

Parameter Comparison

Engineering Selection Recommendations

Both substitute parts are active products with established supply chains, addressing the obsolescence of the MICROSMD400LR-2. The 1210L400SLWR is a Littelfuse product within the same manufacturer ecosystem, maintaining design continuity. The PTSLR12106V400 from Eaton provides an alternative source with equivalent electrical specifications and dual agency approvals (cURus, TUV).

Selection between substitutes should prioritize supply availability and existing qualification status within your manufacturing environment. Both parts satisfy the core electrical requirements and compliance mandates of the original component.

Frequently Asked Questions (FAQ)

Q: Can the 1210L400SLWR directly replace the MICROSMD400LR-2 in existing designs?

A: Yes. Both parts share identical voltage (6V), current hold (4A), and package specifications (1210 surface mount). The 1210L400SLWR operates across an extended temperature range (-40°C to 85°C versus -40°C to 80°C) and carries active product status with improved availability.

Q: What is the difference between the two substitute parts?

A: Both meet the core electrical requirements. The 1210L400SLWR is manufactured by Littelfuse and carries MSL 1 (unlimited moisture sensitivity). The PTSLR12106V400 is manufactured by Eaton with MSL 2A (4 weeks). Thickness differs slightly: 1.00mm for 1210L400SLWR versus 1.20mm for PTSLR12106V400.

Q: Are there any compatibility concerns with the concave package variant?

A: The substitute parts feature a concave package geometry, a standard design variation within the 1210 (3225 Metric) classification. This does not affect electrical performance or PCB footprint compatibility for standard surface mount assembly processes.

Q: Do both substitutes meet compliance requirements?

A: Yes. Both substitute parts are ROHS3 compliant and carry cURus and TUV approvals, meeting or exceeding the compliance profile of the original MICROSMD400LR-2.