PFNF.035.2 Polymeric PTC Resettable Fuse 6V 350mA 1206 Equivalent & Substitute Parts

Part Overview

The PFNF.035.2 is a polymeric PTC resettable fuse manufactured by SCHURTER Inc., designed for surface mount applications in the 1206 (3216 Metric) package. This component provides overcurrent protection with automatic reset capability, operating at 6V with a 350mA hold current. The part is active in production and widely used in consumer electronics, industrial control, and telecommunications equipment where circuit protection and component longevity are critical requirements.

Equivalent and substitute parts are necessary when the primary manufacturer part becomes unavailable, when alternative sourcing reduces lead times, or when design requirements permit operation at higher voltage ratings while maintaining compatible electrical and mechanical characteristics.

Key Parameters

Parameter	Value
Manufacturer Part Number	PFNF.035.2
Manufacturer	SCHURTER Inc.
Type	Polymeric PTC Resettable Fuse
Voltage - Max	6V
Current - Hold (Ih) (Max)	350 mA
Current - Trip (It)	750 mA
Resistance - Initial (Ri) (Min)	300 mOhms
Resistance - Post Trip (R1) (Max)	1.2 Ohms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	1206 (3216 Metric), Concave
Size / Dimension	0.126" L x 0.063" W (3.20mm x 1.60mm)
Thickness (Max)	0.033" (0.85mm)
Approval Agency	cURus, TUV
RoHS Status	ROHS3 Compliant
Product Status	Active

Substitute Part Grouping Explanation

Substitute parts for the PFNF.035.2 are classified into three categories based on electrical and mechanical compatibility:

Direct Substitutes (Identical Electrical Characteristics) Direct substitutes maintain the same voltage rating (6V), hold current (350mA), trip current (750mA), initial resistance (300mOhms minimum), and post-trip resistance (1.2 Ohms maximum). These parts are mechanically compatible with the 1206 package footprint and operate within the same temperature range (-40°C to 85°C). Direct substitutes include the Littelfuse 1206L035YR and Bourns MF-NSMF035-2.

Voltage-Rated Substitutes (Higher Voltage, Same Current) These parts maintain the 350mA hold current and 750mA trip current specifications but operate at higher maximum voltages (16V). The electrical protection characteristics remain functionally equivalent for 6V circuit applications, as the higher voltage rating provides additional safety margin. Mechanical compatibility with the 1206 package is maintained. This category includes the Littelfuse 1206L035/16YR, RFE/Fuzetec FSMD035-1206-R, and Eaton PTS120616V035.

Current-Rated Substitutes (Same Voltage, Higher Current) These parts maintain the 6V voltage rating but operate at higher hold currents (750mA and 1.5A respectively). These are classified as similar parts rather than direct substitutes, as they provide different protection thresholds. This category includes the Littelfuse NANOSMDC075F-2 and NANOSMDC150F-2.

Parameter Comparison

Part Number	Manufacturer	Voltage (Max)	Ih (Max)	It	Ri (Min)	R1 (Max)	Package	Size (mm)	Thickness (Max)	RoHS	Approval
PFNF.035.2	SCHURTER	6V	350mA	750mA	300mOhms	1.2Ω	1206 Concave	3.20 x 1.60	0.85mm	ROHS3	cURus, TUV
1206L035YR	Littelfuse	6V	350mA	750mA	300mOhms	1.2Ω	1206 Concave	3.20 x 1.65	0.75mm	ROHS3	cURus, TUV
1206L035/16YR	Littelfuse	16V	350mA	750mA	300mOhms	1.2Ω	1206 Concave	3.20 x 1.65	0.75mm	ROHS3	cURus, TUV
FSMD035-1206-R	RFE/Fuzetec	16V	350mA	750mA	300mOhms	1.2Ω	1206 Concave	3.25 x 1.65	0.75mm	ROHS3	cUL, TUV, UL
PTS120616V035	Eaton	16V	350mA	750mA	250mOhms	1.2Ω	1206 Concave	3.25 x 1.65	0.68mm	ROHS3	cURus, TUV
MF-NSMF035-2	Bourns	6V	350mA	750mA	300mOhms	1.2Ω	1206 Concave	3.20 x 1.60	0.85mm	ROHS3	cURus, TUV
NANOSMDC075F-2	Littelfuse	6V	750mA	1.5A	90mOhms	300mOhms	1206 Concave	3.20 x 1.59	0.68mm	ROHS3	CSA, TUV, UL
NANOSMDC150F-2	Littelfuse	6V	1.5A	3A	40mOhms	110mOhms	1206 Concave	3.20 x 1.59	0.89mm	ROHS3	CSA, TUV, UL

Engineering Selection Recommendations

For Direct Replacement (Identical Electrical Function)

The Littelfuse 1206L035YR and Bourns MF-NSMF035-2 are direct electrical and mechanical equivalents to the PFNF.035.2. Both maintain 6V maximum voltage, 350mA hold current, and 1206 package compatibility. The Littelfuse part offers higher inventory availability (233,601 units) and is certified by cURus and TUV. The Bourns part includes AEC-Q200 automotive qualification and is also cURus and TUV certified. Both are ROHS3 compliant and suitable for immediate substitution without circuit redesign.

For Higher Voltage Tolerance Applications

When circuit design permits operation at higher voltage ratings, the Littelfuse 1206L035/16YR, RFE/Fuzetec FSMD035-1206-R, and Eaton PTS120616V035 provide 16V maximum voltage while maintaining 350mA hold current and 750mA trip current. These parts are mechanically compatible with the 1206 footprint. The Littelfuse 16V variant has the highest inventory (81,884 units). The RFE/Fuzetec part includes UL certification in addition to cUL and TUV. The Eaton part features slightly lower initial resistance (250mOhms minimum) and reduced thickness (0.68mm), which may be advantageous in space-constrained designs.

For Higher Current Protection Requirements

The Littelfuse NANOSMDC075F-2 (750mA hold current) and NANOSMDC150F-2 (1.5A hold current) are suitable only when circuit protection requirements exceed 350mA. These parts maintain 6V voltage rating and 1206 package compatibility but provide different protection thresholds. Selection depends on actual circuit current requirements and should not be used as substitutes for the PFNF.035.2 unless protection specifications have changed.

Compliance and Certification Considerations

All listed substitute parts are ROHS3 compliant and hold active product status. The RFE/Fuzetec FSMD035-1206-R and Littelfuse nanoSMD series include UL certification, providing additional regulatory coverage for certain applications. All parts are certified by TUV. Selection should consider specific application requirements for regulatory approvals.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 1206L035/16YR be used in place of the PFNF.035.2 in a 6V circuit?

A: Yes. The 1206L035/16YR maintains identical hold current (350mA), trip current (750mA), and resistance characteristics. The 16V maximum voltage rating is a higher specification that does not prevent operation in 6V circuits. The part is mechanically compatible with the 1206 footprint and provides equivalent protection performance.

Q: What is the difference between direct substitutes and voltage-rated substitutes?

A: Direct substitutes (1206L035YR, MF-NSMF035-2) maintain the same 6V maximum voltage rating as the PFNF.035.2. Voltage-rated substitutes (1206L035/16YR, FSMD035-1206-R, PTS120616V035) operate at 16V maximum but maintain identical current and resistance specifications. Both categories provide equivalent electrical protection for 6V applications.

Q: Are the nanoSMD parts (NANOSMDC075F-2, NANOSMDC150F-2) suitable replacements?

A: No. These parts operate at higher hold currents (750mA and 1.5A respectively) compared to the PFNF.035.2 (350mA). They provide different protection thresholds and should only be selected when circuit protection requirements have changed. They are classified as similar parts, not direct substitutes.

Q: What are the mechanical compatibility considerations?

A: All substitute parts use the 1206 (3216 Metric) package with concave geometry. Dimensional variations are minor: length ranges from 3.20mm to 3.25mm, width from 1.59mm to 1.65mm, and thickness from 0.68mm to 0.89mm. These variations are within standard PCB footprint tolerances and do not affect assembly compatibility. Verify specific PCB design constraints if space is limited.

Q: Which substitute part has the best inventory availability?

A: The Littelfuse 1206L035YR has the highest inventory (233,601 units), followed by the Littelfuse NANOSMDC150F-2 (143,570 units). For direct electrical equivalents at 6V, the 1206L035YR is the preferred choice for lead time reduction.

Q: Do all substitute parts meet the same regulatory certifications?

A: All parts are ROHS3 compliant and TUV certified. The RFE/Fuzetec FSMD035-1206-R and Littelfuse nanoSMD series include additional UL certification. The Bourns MF-NSMF035-2 includes AEC-Q200 automotive qualification. Verify specific certification requirements for your application before selection.

Q: What is the significance of initial resistance (Ri) and post-trip resistance (R1)?

A: Initial resistance (Ri) is the resistance of the fuse in normal operation. Post-trip resistance (R1) is the resistance after the fuse has tripped and is in its high-impedance state. The PFNF.035.2 specifies 300mOhms minimum initial resistance and 1.2 Ohms maximum post-trip resistance. All direct and voltage-rated substitutes maintain these specifications, ensuring equivalent circuit behavior during normal operation and fault conditions.

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