NANOSMD175LR-2 Equivalent & Substitute Parts

Part Overview

The NANOSMD175LR-2 is a Polymeric PTC Resettable Fuse manufactured by Littelfuse Inc., rated for 6V maximum voltage with 1.75 A hold current (Ih) in a 1206 (3216 Metric) surface mount package. This component is classified as Obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The part provides overcurrent protection through automatic resetting without component replacement after fault clearance.

Key Parameters

Parameter	Value
Manufacturer Part Number	NANOSMD175LR-2
Manufacturer	Littelfuse Inc.
Product Type	Polymeric PTC Resettable Fuse
Voltage - Max	6V
Current - Hold (Ih) (Max)	1.75 A
Current - Trip (It)	5 A
Current - Max	50 A
Time to Trip	1 s
Resistance - Initial (Ri) (Min)	8 mOhms
Mounting Type	Surface Mount
Package / Case	1206 (3216 Metric)
Size / Dimension	0.127" L x 0.063" W (3.22mm x 1.60mm)
Thickness (Max)	0.039" (1.00mm)
Product Status	Obsolete
RoHS Status	ROHS3 Compliant
Approval Agency	CSA, TUV, UL

Substitute Part Grouping Explanation

Substitution for the NANOSMD175LR-2 is determined by the following critical parameters:

Voltage Rating: All substitutes must maintain 6V maximum voltage compatibility.

Current - Hold (Ih): The 1.75 A hold current specification defines the normal operating current threshold. Substitutes with identical or higher Ih ratings preserve the original protection characteristics.

Package / Case: The 1206 (3216 Metric) surface mount package defines the physical footprint and PCB compatibility. Substitutes in smaller packages (0402, 0603, 0805) represent downsized alternatives suitable for space-constrained designs, while maintaining electrical equivalence through matched voltage and current ratings.

Mounting Type: All substitutes are surface mount, maintaining assembly process compatibility.

Product Status: Active status substitutes ensure ongoing availability and manufacturing support, contrasting with the Obsolete status of the main part.

The substitute parts are grouped by package size, with each group offering equivalent electrical protection at the specified voltage and current ratings.

Parameter Comparison

Parameter	NANOSMD175LR-2	0603L175SLYR	0805L175SLYR
Voltage - Max	6V	6V	6V
Current - Hold (Ih) (Max)	1.75 A	1.75 A	1.75 A
Current - Trip (It)	5 A	4.6 A	4.6 A
Current - Max	50 A	50 A	50 A
Resistance - Initial (Ri) (Min)	8 mOhms	5 mOhms	5 mOhms
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Package / Case	1206 (3216 Metric)	0603 (1608 Metric)	0805 (2012 Metric)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, TUV, UL	cURus, TUV	cURus, TUV
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

Direct Electrical Equivalents (Matched Ih = 1.75 A):

The 0603L175SLYR and 0805L175SLYR provide direct electrical equivalence with identical 1.75 A hold current ratings. Both parts are Active status with current manufacturing support and ROHS3 compliance. Selection between these two depends on available PCB space: the 0603 package (1.60mm x 0.80mm) suits space-constrained applications, while the 0805 package (2.10mm x 1.35mm) offers improved thermal characteristics and handling robustness.

Lower Current Alternatives (Ih < 1.75 A):

The 0603L150SLYR (1.5 A Ih) and 0805L150SLYR (1.5 A Ih) provide substitution for applications where the full 1.75 A hold current is not required. These parts maintain 6V voltage compatibility and Active product status. The 0603L100SLYR (1 A Ih) and 0603L075SLYR (750 mA Ih) serve lower-current protection requirements.

Smaller Package Options (0402):

The 0402L050SLKR (500 mA Ih) and 0402L035SLKR (350 mA Ih) represent the most compact alternatives for space-critical designs, though with significantly reduced current ratings. These parts are suitable only for applications with lower current requirements than the original 1.75 A specification.

All recommended substitutes maintain ROHS3 compliance and TUV certification, ensuring regulatory and safety standard continuity.

Frequently Asked Questions (FAQ)

Q: Can I use a substitute part with lower hold current (Ih) than the original 1.75 A?

A: Lower Ih ratings will trip at reduced current levels. Use lower-rated substitutes only if your application's normal operating current is below the substitute's Ih specification. Verify that the substitute's trip current (It) and hold current align with your circuit protection requirements.

Q: What is the difference between the 1206, 0603, and 0805 packages?

A: Package size determines PCB footprint and thermal performance. The 1206 (3.22mm x 1.60mm) is the largest, 0805 (2.10mm x 1.35mm) is intermediate, and 0603 (1.60mm x 0.80mm) is the smallest. Smaller packages require tighter PCB layout but occupy less board space. Larger packages generally offer better thermal dissipation.

Q: Are all substitute parts ROHS3 compliant?

A: Yes, all listed substitutes are ROHS3 compliant, matching the original part's environmental compliance status.

Q: What does "Obsolete" product status mean for the original part?

A: Obsolete status indicates the NANOSMD175LR-2 is no longer manufactured. Substitute parts with Active status ensure continued availability for new designs and production replenishment.

Q: Can I substitute a part with higher hold current (Ih)?

A: Higher Ih ratings will not trip until higher fault currents are reached, reducing protection sensitivity. Use higher-rated substitutes only if your application requires protection at elevated current levels.

Q: What is the significance of Resistance - Initial (Ri)?

A: Lower Ri values result in reduced voltage drop across the fuse during normal operation, minimizing power dissipation and heat generation. The substitute parts with 5 mOhms Ri offer improved efficiency compared to the original 8 mOhms specification.

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