NANOSMD400LR-2 Equivalent & Substitute Parts

Part Overview

The NANOSMD400LR-2 is a Polymeric PTC Resettable Fuse manufactured by Littelfuse Inc., rated for 6V at 4A hold current in a 1206 (3216 Metric) surface mount package. This component is classified as Obsolete, making identification of suitable substitute parts essential for ongoing design support and production continuity. The part operates across a temperature range of -40°C to 80°C and complies with ROHS3 standards.

Substiute Parts

NANOSMD400LR-2

Littelfuse Inc.In Stock: 1031NANOSMD400LR-2 Datasheet

Current PartRFQ

1206L400SLWR

Littelfuse Inc.In Stock: 1081881206L400SLWR Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the NANOSMD400LR-2 is determined by strict equivalence across the following electrical and mechanical parameters:

• Voltage rating: 6V maximum
• Current hold (Ih): 4A maximum
• Current trip (It): 8A
• Package type: 1206 (3216 Metric) surface mount
• Polymeric PTC resettable fuse technology
• ROHS3 compliance

The substitute part 1206L400SLWR meets all primary electrical specifications and maintains the same 1206 package footprint, enabling direct functional replacement in circuit designs.

Parameter Comparison

Engineering Selection Recommendations

The 1206L400SLWR is the designated substitute for the obsolete NANOSMD400LR-2. Both components are manufactured by Littelfuse Inc. and share identical electrical ratings for voltage, hold current, trip current, and maximum current specifications. The substitute part is currently in active production status with significantly higher inventory availability (108,100 pcs vs. 978 pcs), ensuring supply chain continuity.

The 1206L400SLWR operates across an extended temperature range (-40°C to 85°C versus -40°C to 80°C) and maintains ROHS3 compliance. The substitute features a Concave package geometry and improved moisture sensitivity rating (MSL 1 versus MSL 2A), along with additional approval certifications (cURus, TUV). Initial resistance is lower (1 mOhms minimum) and post-trip resistance tolerance is slightly higher (14 mOhms maximum), both within acceptable operational parameters for PTC resettable fuse applications.

Frequently Asked Questions (FAQ)

Q: Can the 1206L400SLWR directly replace the NANOSMD400LR-2 on existing PCBs?

A: Yes. Both components share the 1206 (3216 Metric) surface mount package footprint and identical electrical ratings (6V, 4A hold, 8A trip). The substitute features a Concave package variant, which maintains PCB compatibility while offering improved performance characteristics.

Q: What are the differences in resistance specifications between these parts?

A: The NANOSMD400LR-2 specifies 4 mOhms minimum initial resistance and 10 mOhms maximum post-trip resistance. The 1206L400SLWR specifies 1 mOhms minimum initial resistance and 14 mOhms maximum post-trip resistance. Both values remain within acceptable operating ranges for PTC resettable fuse functionality in 6V, 4A applications.

Q: Why is the substitute part rated for a higher operating temperature?

A: The 1206L400SLWR extends the upper operating temperature limit to 85°C compared to the NANOSMD400LR-2 at 80°C. This represents an enhancement in the substitute part's thermal capability and does not restrict its use in applications designed for the original part's temperature range.

Q: What is the significance of the Concave package designation?

A: The Concave geometry is a physical package variant that maintains the same 1206 footprint dimensions and electrical performance. This design feature is standard in the POLY-FUSE LoRho series and does not affect PCB assembly or circuit functionality.

Q: Are there compliance or certification differences?

A: Both parts are ROHS3 compliant. The substitute part 1206L400SLWR carries additional approvals (cURus, TUV) and features an improved moisture sensitivity level (MSL 1 Unlimited versus MSL 2A 4 Weeks), providing enhanced reliability for storage and handling.