NANOSMD270LR-2 Equivalent & Substitute Parts

Part Overview

The NANOSMD270LR-2 is a Polymeric PTC Resettable Fuse manufactured by Littelfuse Inc., rated for 6V maximum voltage with a 2.7 A hold current (Ih). This component is packaged in a 1206 (3216 Metric) surface mount form factor and is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from the active POLY-FUSE® and LoRho series are necessary for new designs and ongoing production requirements. Substitutes must maintain 6V voltage rating and provide comparable or lower hold current ratings depending on circuit protection requirements.

Key Parameters

Parameter	NANOSMD270LR-2 Value
Manufacturer	Littelfuse Inc.
Voltage - Max	6V
Current - Hold (Ih) (Max)	2.7 A
Current - Trip (It)	6.3 A
Type	Polymeric
Mounting Type	Surface Mount
Package / Case	1206 (3216 Metric)
Resistance - Initial (Ri) (Min)	5 mOhms
Product Status	Obsolete
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the NANOSMD270LR-2 is determined by the following criteria:

Mandatory Matching Parameters:

Voltage Rating: 6V maximum (all substitutes must be rated 6V)
Type: Polymeric PTC resettable fuse
Manufacturer: Littelfuse Inc. (POLY-FUSE® or LoRho series)
RoHS Compliance: ROHS3 Compliant

Current Rating Flexibility: Substitutes are grouped by hold current (Ih) rating. The NANOSMD270LR-2 with 2.7 A Ih can be replaced by parts with equal or lower Ih ratings, depending on circuit requirements. Lower Ih ratings provide more sensitive protection; higher Ih ratings are not suitable as direct substitutes.

Package Considerations: The original 1206 package can be substituted with smaller packages (0402, 0603, 0805) if board space and thermal management allow. Smaller packages have lower thermal mass and may exhibit faster trip times.

Active vs. Obsolete Status: All substitute parts listed are in Active product status, ensuring long-term availability and supply chain continuity.

Parameter Comparison

Part Number	Voltage (Max)	Ih (Max)	It	Package	Ri (Min)	Product Status	Approval Agency
NANOSMD270LR-2	6V	2.7 A	6.3 A	1206 (3216 Metric)	5 mOhms	Obsolete	CSA, TUV, UL
0402L035SLKR	6V	350 mA	700 mA	0402 (1005 Metric)	50 mOhms	Active	cURus, TUV
0402L050SLKR	6V	500 mA	1 A	0402 (1005 Metric)	40 mOhms	Active	cURus, TUV
0603L050SLYR	6V	500 mA	1 A	0603 (1608 Metric)	70 mOhms	Active	cURus, TUV
0603L075SLYR	6V	750 mA	1.5 A	0603 (1608 Metric)	20 mOhms	Active	cURus, TUV
0603L100SLYR	6V	1 A	1.8 A	0603 (1608 Metric)	40 mOhms	Active	cURus, TUV
0603L150SLYR	6V	1.5 A	3 A	0603 (1608 Metric)	7 mOhms	Active	cURus, TUV
0603L175SLYR	6V	1.75 A	4.6 A	0603 (1608 Metric)	5 mOhms	Active	cURus, TUV
0805L110SLYR	6V	1.1 A	1.8 A	0805 (2012 Metric)	30 mOhms	Active	cURus, TUV
0805L150SLYR	6V	1.5 A	3 A	0805 (2012 Metric)	15 mOhms	Active	cURus, TUV
0805L175SLYR	6V	1.75 A	4.6 A	0805 (2012 Metric)	5 mOhms	Active	cURus, TUV

Engineering Selection Recommendations

For Direct Replacement (Same Protection Level): The 0603L175SLYR and 0805L175SLYR are the closest functional equivalents to the NANOSMD270LR-2, with 1.75 A Ih ratings that approach the original 2.7 A specification. Both are Active products with current certifications (cURus, TUV) and ROHS3 compliance. The 0603L175SLYR offers a smaller footprint; the 0805L175SLYR provides improved thermal characteristics in a slightly larger package.

For Lower Protection Sensitivity: If circuit design permits lower hold current thresholds, the 0603L150SLYR and 0805L150SLYR (1.5 A Ih) provide enhanced protection with Active status and full compliance certifications.

For Compact Board Layouts: The 0402 series (0402L035SLKR, 0402L050SLKR) are suitable only for applications requiring significantly lower hold currents (350 mA to 500 mA). These are not recommended as direct replacements for the 2.7 A specification.

Compliance Verification: All substitute parts maintain ROHS3 compliance and are certified by cURus and TUV. The original NANOSMD270LR-2 carried CSA, TUV, and UL approvals; substitute selection should confirm that required certifications align with end-application standards.

Frequently Asked Questions (FAQ)

Q: Can I use a lower Ih-rated part as a substitute for the NANOSMD270LR-2? A: Yes, lower Ih ratings provide more sensitive circuit protection and will trip at lower current levels. However, this changes the protection profile of the circuit. Verify that the lower threshold does not cause nuisance trips in normal operation.

Q: What is the difference between the 0603 and 0805 packages? A: The 0805 (2012 Metric) is larger than the 0603 (1608 Metric), offering greater thermal mass and potentially slower trip times. The 0603 is more compact. Both are suitable for the same voltage and current ratings; package selection depends on board space and thermal management requirements.

Q: Why is the NANOSMD270LR-2 listed as obsolete? A: Obsolete status indicates the part is no longer manufactured or supported by Littelfuse. Active alternatives from the POLY-FUSE® and LoRho series provide equivalent functionality with ongoing supply availability and support.

Q: Are all substitute parts RoHS compliant? A: Yes, all listed substitutes are ROHS3 compliant. The original NANOSMD270LR-2 is also ROHS3 compliant, ensuring environmental and regulatory consistency.

Q: Can I substitute a 6V fuse with a higher voltage rating? A: No. The voltage rating must match or be lower than the original specification. Using a higher voltage-rated fuse would compromise circuit protection.

Q: What does "Ih" (hold current) mean? A: Ih is the maximum current the fuse can carry indefinitely without tripping. Above this threshold, the fuse enters a trip state. The NANOSMD270LR-2 has an Ih of 2.7 A, meaning it will not trip under continuous 2.7 A operation but will trip when current exceeds the trip threshold (It = 6.3 A).

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