PFLT.300 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The PFLT.300 is a polymeric PTC resettable fuse manufactured by SCHURTER Inc., rated for 24V at 3A hold current with a 6.3A trip threshold. This component is classified as obsolete, making identification of functionally equivalent alternatives essential for ongoing system support and procurement planning. The PFLT series provides overcurrent protection in applications requiring automatic reset capability without component replacement.

Key Parameters

Parameter	Value
Voltage - Max	24V
Current - Hold (Ih) (Max)	3 A
Current - Trip (It)	6.3 A
Current - Max	100 A
Time to Trip	4 s
Resistance - Initial (Ri) (Min)	15 mOhms
Resistance - Post Trip (R1) (Max)	55 mOhms
Operating Temperature	-45°C ~ 85°C
Type	Polymeric
Package / Case	Strap
Size / Dimension	1.185" L x 0.532" W (30.10mm x 14.60mm)
Thickness (Max)	0.043" (1.10mm)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution of the PFLT.300 is determined by strict equivalence across the following critical parameters:

Voltage rating: 24V maximum
Hold current (Ih): 3A maximum
Trip current (It): 6.3A
Time to trip: 4 seconds
Initial resistance (Ri): 15 mOhms minimum
Post-trip resistance (R1): 55 mOhms maximum
Package type: Strap configuration
Polymeric PTC technology classification

The MF-LS300 from Bourns Inc. meets all specified electrical and mechanical parameters, with minor dimensional tolerance variations within acceptable engineering margins. Both components maintain identical voltage, current, and resistance specifications required for direct functional replacement.

Parameter Comparison

Parameter	PFLT.300 (SCHURTER)	MF-LS300 (Bourns)	Match Status
Voltage - Max	24V	24V	Equivalent
Current - Hold (Ih) (Max)	3 A	3 A	Equivalent
Current - Trip (It)	6.3 A	6.3 A	Equivalent
Current - Max	100 A	100 A	Equivalent
Time to Trip	4 s	4 s	Equivalent
Resistance - Initial (Ri) (Min)	15 mOhms	15 mOhms	Equivalent
Resistance - Post Trip (R1) (Max)	55 mOhms	55 mOhms	Equivalent
Operating Temperature	-45°C ~ 85°C	-40°C ~ 85°C	Compatible*
Type	Polymeric	Polymeric	Equivalent
Package / Case	Strap	Strap	Equivalent
Size / Dimension	1.185" L x 0.532" W (30.10mm x 14.60mm)	1.185" L x 0.522" W (30.10mm x 13.25mm)	Compatible*
Thickness (Max)	0.043" (1.10mm)	0.043" (1.10mm)	Equivalent
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Equivalent

*Compatible: Minor variations within acceptable mechanical tolerances for strap-mounted components.

Engineering Selection Recommendations

The MF-LS300 (Bourns Multifuse® series) is the direct functional equivalent for PFLT.300 replacement applications. Selection rationale is based on the following factors:

Electrical parameter equivalence across all critical specifications (voltage, current, resistance, trip time)
Active product status of MF-LS300 ensures ongoing availability and supply chain continuity
Both components maintain ROHS3 compliance and REACH unaffected status
Identical polymeric PTC technology and strap package configuration
Approval certifications (TUV, UL/cURus) support regulatory compliance requirements
Dimensional compatibility within standard mechanical tolerances for strap-mounted applications

The MF-LS300 is suitable for direct substitution in applications currently using the obsolete PFLT.300 without circuit redesign or performance degradation.

Frequently Asked Questions (FAQ)

Q: Can the MF-LS300 be used as a direct replacement for PFLT.300?

A: Yes. The MF-LS300 meets all electrical specifications (24V, 3A hold, 6.3A trip, 4s response time) and mechanical requirements (strap package, equivalent dimensions) required for direct substitution.

Q: What are the key differences between these two parts?

A: The primary differences are manufacturer (SCHURTER vs. Bourns), product status (obsolete vs. active), and minor operating temperature range variation (-45°C to 85°C vs. -40°C to 85°C). All electrical and mechanical parameters are equivalent.

Q: Are there any compatibility concerns with the dimensional differences?

A: No. The width variation (0.532" vs. 0.522", or 14.60mm vs. 13.25mm) is within standard mechanical tolerances for strap-mounted components and does not affect functional compatibility or mounting.

Q: What certifications apply to the MF-LS300?

A: The MF-LS300 carries cURus and TUV approvals. Both the PFLT.300 and MF-LS300 are ROHS3 compliant and REACH unaffected.

Q: Why is the PFLT.300 listed as obsolete?

A: Obsolete status indicates the part is no longer manufactured by SCHURTER Inc. The MF-LS300 provides equivalent functionality with active manufacturing status and ongoing supply availability.

Q: Can these parts be used interchangeably in existing designs?

A: Yes. Identical electrical parameters and strap package configuration support direct interchangeability without circuit modification or performance impact.

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