PFST.200 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The PFST.200 is a polymeric PTC resettable fuse manufactured by SCHURTER Inc., rated for 30V at 2A hold current with a 4.4A trip current. This component is classified as obsolete, making equivalent substitutes necessary for ongoing design support and procurement. Polymeric PTC resettable fuses function as automatic circuit protection devices that increase resistance when exposed to overcurrent conditions, then reset when the fault is cleared. The PFST.200 operates across a temperature range of -40°C to 85°C and meets CSA, TUV, and UL approval standards.

Key Parameters

Parameter	Value
Voltage - Max	30V
Current - Hold (Ih) (Max)	2 A
Current - Trip (It)	4.4 A
Current - Max	100 A
Time to Trip	4 s
Resistance - Initial (Ri) (Min)	30 mOhms
Operating Temperature	-40°C ~ 85°C
Package / Case	Strap
Size / Dimension	0.880" L x 0.417" W (22.35mm x 10.60mm)
Thickness (Max)	0.043" (1.10mm)
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution for the PFST.200 is determined by strict equivalence across the following electrical and mechanical parameters:

Maximum voltage rating: 30V
Hold current (Ih): 2A
Trip current (It): 4.4A
Maximum current capacity: 100A
Time to trip: 4 seconds
Initial resistance (Ri): 30 mOhms minimum
Operating temperature range: -40°C to 85°C
Package type: Strap configuration
Physical dimensions: 0.880" L x 0.417" W (22.35mm x 10.60mm)
Thickness: 0.043" (1.10mm) maximum
Regulatory compliance: CSA, TUV, UL approval

The two identified substitutes—SRP200F (Littelfuse Inc.) and MF-S200 (Bourns Inc.)—meet all these core parameters and maintain functional equivalence for direct replacement applications.

Parameter Comparison

Parameter	PFST.200 (SCHURTER)	SRP200F (Littelfuse)	MF-S200 (Bourns)
Manufacturer	SCHURTER Inc.	Littelfuse Inc.	Bourns Inc.
Series	PFST	PolySwitch®, SRP	Multifuse®, MF-S
Product Status	Obsolete	Active	Active
Type	Polymeric	Polymeric	Polymeric
Voltage - Max	30V	30V	30V
Current - Hold (Ih) (Max)	2 A	2 A	2 A
Current - Trip (It)	4.4 A	4.4 A	4.4 A
Current - Max	100 A	100 A	100 A
Time to Trip	4 s	4 s	4 s
Resistance - Initial (Ri) (Min)	30 mOhms	30 mOhms	30 mOhms
Resistance - Post Trip (R1) (Max)	80 mOhms	100 mOhms	80 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	Strap	Strap	Strap
Size / Dimension	0.880" L x 0.417" W (22.35mm x 10.60mm)	0.880" L x 0.417" W (22.35mm x 10.60mm)	0.880" L x 0.417" W (22.35mm x 10.60mm)
Thickness (Max)	0.043" (1.10mm)	0.043" (1.10mm)	0.043" (1.10mm)
Approval Agency	CSA, TUV, UL	CSA, TUV, UL	cURus, TUV
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

Both SRP200F and MF-S200 are active production parts suitable for replacing the obsolete PFST.200. Selection between these substitutes should be based on the following factors:

SRP200F (Littelfuse Inc.): This part maintains full compliance with CSA, TUV, and UL standards. Post-trip resistance is specified at 100 mOhms maximum, which is within acceptable tolerance for this application class. Littelfuse maintains extensive inventory (65,516 pieces in stock), ensuring supply continuity. Packaging is bulk format.

MF-S200 (Bourns Inc.): This part meets cURus and TUV approval standards. Post-trip resistance is specified at 80 mOhms maximum, matching the original PFST.200 specification exactly. Bourns inventory availability is 6,341 pieces. Packaging is bulk format.

Both parts are ROHS3 compliant and REACH unaffected. The primary differentiation lies in approval agency coverage and post-trip resistance specification. Applications requiring full CSA/TUV/UL compliance should prioritize SRP200F. Applications with tighter post-trip resistance tolerance should prioritize MF-S200.

Frequently Asked Questions (FAQ)

Q: Can SRP200F and MF-S200 be used interchangeably with PFST.200?

A: Yes. Both parts meet all electrical and mechanical parameters specified for the PFST.200, including voltage rating, hold current, trip current, operating temperature range, physical dimensions, and regulatory certifications. Direct substitution is supported.

Q: What is the difference in post-trip resistance between the substitutes?

A: SRP200F specifies post-trip resistance (R1) at 100 mOhms maximum, while MF-S200 specifies 80 mOhms maximum. Both values are within acceptable operating ranges for polymeric PTC resettable fuses in this current class. Selection depends on circuit design requirements for post-trip voltage drop and power dissipation.

Q: Are there differences in regulatory approvals?

A: SRP200F carries CSA, TUV, and UL approvals. MF-S200 carries cURus and TUV approvals. Applications requiring full CSA/UL compliance should use SRP200F. Both meet TUV standards.

Q: What is the strap package configuration?

A: The strap package is a user-defined mounting format with dimensions of 0.880" length by 0.417" width (22.35mm x 10.60mm) and 0.043" maximum thickness (1.10mm). This configuration is consistent across all three parts and supports direct mechanical interchange.

Q: Why is PFST.200 listed as obsolete?

A: PFST.200 is no longer in active production by SCHURTER Inc. SRP200F and MF-S200 are active production equivalents that provide identical electrical performance and mechanical compatibility for new designs and legacy system support.

Q: Are all three parts ROHS3 compliant?

A: Yes. PFST.200, SRP200F, and MF-S200 are all ROHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements for electronic component manufacturing and distribution.

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