LTP100S Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The LTP100S is a polymeric PTC resettable fuse manufactured by Littelfuse Inc., part of the PolySwitch® LTP series. This component is rated for 24V maximum voltage with a 1A hold current and is designed for circuit protection applications requiring automatic reset capability. The LTP100S is classified as obsolete, making identification of active equivalent parts essential for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value
Voltage - Max	24V
Current - Hold (Ih) (Max)	1 A
Current - Trip (It)	2.5 A
Current - Max	100 A
Time to Trip	7 s
Resistance - Initial (Ri) (Min)	70 mOhms
Resistance - Post Trip (R1) (Max)	260 mOhms
Operating Temperature	-40°C ~ 85°C
Package / Case	Strap
Size / Dimension	0.866" L x 0.199" W (22.00mm x 5.05mm)
Thickness (Max)	0.039" (1.00mm)
Type	Polymeric

Substitute Part Grouping Explanation

Substitution of the LTP100S is determined by strict equivalence across the following critical parameters:

Voltage rating: 24V maximum
Hold current (Ih): 1A maximum
Trip current (It): 2.5A
Time to trip: 7 seconds
Initial resistance (Ri): 70 mOhms minimum
Post-trip resistance (R1): 260 mOhms maximum
Operating temperature range: -40°C to 85°C
Package type: Strap configuration
Physical dimensions: 22.00mm L x 5.05mm W x 1.00mm thickness

The MF-LS100 from Bourns Inc. meets all specified electrical and mechanical parameters, establishing it as a parametric equivalent for the obsolete LTP100S.

Parameter Comparison

Parameter	LTP100S (Littelfuse)	MF-LS100 (Bourns)	Match
Voltage - Max	24V	24V	✓
Current - Hold (Ih) (Max)	1 A	1 A	✓
Current - Trip (It)	2.5 A	2.5 A	✓
Current - Max	100 A	100 A	✓
Time to Trip	7 s	7 s	✓
Resistance - Initial (Ri) (Min)	70 mOhms	70 mOhms	✓
Resistance - Post Trip (R1) (Max)	260 mOhms	260 mOhms	✓
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	✓
Package / Case	Strap	Strap	✓
Size / Dimension	22.00mm L x 5.05mm W	22.00mm L x 5.05mm W	✓
Thickness (Max)	1.00mm	1.00mm	✓
Type	Polymeric	Polymeric	✓
Series	PolySwitch® LTP	Multifuse® MF-LS	Different series, equivalent function
Product Status	Obsolete	Active	✓ (Active status preferred)
RoHS Status	RoHS non-compliant	ROHS3 Compliant	✓ (Improved compliance)

Engineering Selection Recommendations

The MF-LS100 is the appropriate substitute for the obsolete LTP100S based on the following factors:

All electrical parameters match exactly: voltage rating, hold current, trip current, time to trip, and resistance specifications are identical across both components.

Mechanical compatibility is confirmed: package type, physical dimensions, and thickness specifications are equivalent, ensuring direct replacement in existing circuit board layouts and mechanical assemblies.

Product status: The MF-LS100 is classified as active, providing long-term availability and supply chain continuity compared to the obsolete LTP100S.

Regulatory compliance: The MF-LS100 achieves ROHS3 compliance, whereas the LTP100S is RoHS non-compliant. Both components maintain CSA, TUV, and UL certifications (MF-LS100 includes UR certification). Both are REACH unaffected and classified under ECCN EAR99.

Moisture sensitivity: The MF-LS100 offers improved moisture handling with MSL 1 (unlimited storage) compared to the LTP100S MSL 2A (4 weeks).

Frequently Asked Questions (FAQ)

Q: Can the MF-LS100 be used as a direct replacement for the LTP100S?

A: Yes. The MF-LS100 meets all electrical and mechanical specifications of the LTP100S. Both components share identical voltage ratings, current ratings, trip characteristics, resistance values, operating temperature range, and physical dimensions. Direct substitution is supported.

Q: What is the primary reason to transition from LTP100S to MF-LS100?

A: The LTP100S is obsolete, creating procurement and supply chain risk. The MF-LS100 is an active product with equivalent performance specifications and improved regulatory compliance (ROHS3).

Q: Are there any differences in package or mounting between these parts?

A: No. Both components use strap packaging with identical dimensions (22.00mm L x 5.05mm W x 1.00mm thickness) and user-defined mounting type. No circuit board layout modifications are required.

Q: How do the certifications compare?

A: Both parts hold CSA, TUV, and UL certifications. The MF-LS100 additionally includes UR certification. Both are REACH unaffected and classified as EAR99.

Q: What is the difference in moisture sensitivity levels?

A: The LTP100S has MSL 2A (4-week storage limit), while the MF-LS100 has MSL 1 (unlimited storage). The MF-LS100 offers superior moisture handling characteristics.

Q: Are the electrical trip characteristics identical?

A: Yes. Both components have identical hold current (1A), trip current (2.5A), time to trip (7 seconds), initial resistance (70 mOhms minimum), and post-trip resistance (260 mOhms maximum).

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