MICROSMD380LR-2 Equivalent & Substitute Parts

Part Overview

The MICROSMD380LR-2 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., rated for 6V at 3.8A hold current in a 1210 (3225 Metric) surface mount package. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing design support and procurement planning. Substitute parts must maintain electrical performance within the specified voltage, current, and thermal parameters while accommodating available packaging and certification requirements.

Substiute Parts

MICROSMD380LR-2

Littelfuse Inc.In Stock: 978MICROSMD380LR-2 Datasheet

Current PartRFQ

1210L380SLYR

Littelfuse Inc.In Stock: 44561210L380SLYR Datasheet

MFR RecommendedRFQ

PTSLR12106V380

Eaton - Electronics DivisionIn Stock: 822PTSLR12106V380 Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MICROSMD380LR-2 is determined by the following criteria:

Electrical Parameters (Critical):

• Voltage rating must equal or exceed 6V maximum
• Current hold (Ih) must equal 3.8A
• Package and case must be 1210 (3225 Metric) surface mount
• RoHS3 compliance required

Acceptable Variations:

• Current trip (It) may vary within the polymeric PTC fuse operating range
• Time to trip may vary based on material composition
• Initial and post-trip resistance values may vary within acceptable limits for the 3.8A hold current class
• Operating temperature range may extend beyond -40°C ~ 80°C
• Moisture sensitivity level may differ
• Approval agencies may differ (CSA, UL, cURus, TUV all acceptable)

The following parts meet these substitution criteria:

1. 1210L380SLYR (Littelfuse Inc., POLY-FUSE® LoRho series) – Obsolete status, identical electrical rating
2. PTSLR12106V380 (Eaton Electronics Division, PTSLR1210 series) – Active status, identical electrical rating

Parameter Comparison

Engineering Selection Recommendations

For New Designs and Long-Term Availability: PTSLR12106V380 (Eaton Electronics Division) is the preferred substitute. This part maintains active product status, ensuring continued availability and supply chain stability. It meets all electrical requirements at the 3.8A hold current rating and carries cURus and TUV certifications. The extended operating temperature range (-40°C ~ 85°C) provides additional thermal margin compared to the original part.

For Legacy System Maintenance: 1210L380SLYR (Littelfuse Inc., POLY-FUSE® LoRho series) provides direct electrical equivalence and maintains Littelfuse manufacturing continuity. However, this part is also obsolete; inventory availability should be confirmed before design commitment.

Mechanical Considerations: Both substitute parts feature concave package geometry and reduced thickness compared to the original MICROSMD380LR-2. PCB layout and component placement must accommodate these dimensional differences. The PTSLR12106V380 has maximum thickness of 0.047" (1.20mm), while the 1210L380SLYR measures 0.028" (0.70mm) maximum.

Compliance: All three parts are ROHS3 compliant. Certification differences (CSA/UL versus cURus/TUV) reflect regional approval standards and do not affect functional substitution within the specified electrical parameters.

Frequently Asked Questions (FAQ)

Q: Can PTSLR12106V380 directly replace MICROSMD380LR-2 in existing designs? A: Yes. Both parts are rated 6V at 3.8A hold current in 1210 (3225 Metric) surface mount packages. Electrical performance is equivalent. Verify PCB layout accommodates the concave package geometry and 0.047" (1.20mm) maximum thickness of the PTSLR12106V380.

Q: What is the difference between Current - Hold (Ih) and Current - Trip (It)? A: Current - Hold (Ih) is the maximum continuous current the fuse allows without tripping; all three parts hold 3.8A. Current - Trip (It) is the threshold at which the fuse activates; the MICROSMD380LR-2 trips at 9A, while both substitutes trip at 8A. This difference is within acceptable polymeric PTC fuse operating ranges.

Q: Why do the substitute parts have different time-to-trip values? A: Time to trip varies based on material composition and thermal characteristics of the polymeric PTC element. The MICROSMD380LR-2 requires 10 seconds, 1210L380SLYR requires 5 seconds, and PTSLR12106V380 requires 2 seconds. Selection depends on circuit protection speed requirements.

Q: Are there packaging differences between these parts? A: Yes. The MICROSMD380LR-2 has standard 1210 geometry with 0.039" (1.00mm) maximum thickness. Both substitutes feature concave package geometry with different thicknesses: 1210L380SLYR at 0.028" (0.70mm) and PTSLR12106V380 at 0.047" (1.20mm). Confirm PCB footprint and clearance compatibility.

Q: Which part should I choose for new production? A: PTSLR12106V380 (Eaton Electronics Division) is recommended for new designs due to active product status and assured long-term availability. It meets all electrical specifications and carries appropriate industrial certifications.

Q: What is the significance of Moisture Sensitivity Level (MSL)? A: MSL indicates how long a component can be stored in ambient conditions before requiring baking. MICROSMD380LR-2 and PTSLR12106V380 are MSL 2A (4 weeks), while 1210L380SLYR is MSL 1 (unlimited). Lower MSL values provide greater storage flexibility.