PFMF.125.2 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The PFMF.125.2 is a polymeric PTC resettable fuse manufactured by SCHURTER Inc., rated for 6V at 1.25A hold current in a surface mount 1812 (4532 Metric) package. This component is active in production and widely used for overcurrent protection in electronic circuits. Equivalent and substitute parts are identified to provide design flexibility, supply chain alternatives, and component availability options while maintaining electrical and mechanical compatibility within specified parameters.

Key Parameters

Parameter	Value
Voltage - Max	6V
Current - Hold (Ih) (Max)	1.25 A
Current - Trip (It)	2.5 A
Current - Max	100 A
Time to Trip	400 ms
Resistance - Initial (Ri) (Min)	35 mOhms
Resistance - Post Trip (R1) (Max)	140 mOhms
Operating Temperature	-40°C ~ 85°C
Mounting Type	Surface Mount
Package / Case	1812 (4532 Metric), Concave
Size / Dimension	0.179" L x 0.128" W (4.55mm x 3.24mm)
Thickness (Max)	0.033" (0.85mm)
RoHS Status	ROHS3 Compliant
Approval Agency	cURus, TUV

Substitute Part Grouping Explanation

Substitute parts for the PFMF.125.2 are classified into three categories based on electrical and mechanical parameter alignment:

Direct Manufacturer Equivalent (MINISMDC125F-2): Identical electrical specifications including 6V maximum voltage, 1.25A hold current, 2.5A trip current, and 400ms trip time. Package and footprint are identical (1812/4532 Metric). Initial resistance differs slightly (50 mOhms vs. 35 mOhms minimum), and post-trip resistance remains within specification (140 mOhms maximum). Thickness is reduced to 0.019" (0.48mm), providing a lower-profile alternative. Approval agencies include CSA, TUV, and UL.

Similar Manufacturer Part (NANOSMDC200F-2): Shares the same 6V maximum voltage and operating temperature range but differs in current ratings (2A hold current vs. 1.25A) and package size (1206/3216 Metric vs. 1812/4532 Metric). This part is suitable only when higher current capacity is acceptable and PCB layout accommodates the smaller footprint. Trip current is 4A with 1.5s trip time.

Parametric Equivalent (MF-MSMF125-2): Matches all critical electrical parameters of the main part (6V, 1.25A hold, 2.5A trip, 400ms trip time) and maintains identical package dimensions (1812/4532 Metric). Initial and post-trip resistance values are identical. Moisture sensitivity level is superior (1 vs. Not Applicable), and AEC-Q200 automotive qualification is included.

Parameter Comparison

Parameter	PFMF.125.2 (Main)	MINISMDC125F-2 (Direct)	NANOSMDC200F-2 (Similar)	MF-MSMF125-2 (Parametric)
Manufacturer	SCHURTER Inc.	Littelfuse Inc.	Littelfuse Inc.	Bourns Inc.
Voltage - Max	6V	6V	6V	6V
Current - Hold (Ih) (Max)	1.25 A	1.25 A	2 A	1.25 A
Current - Trip (It)	2.5 A	2.5 A	4 A	2.5 A
Current - Max	100 A	100 A	100 A	100 A
Time to Trip	400 ms	400 ms	1.5 s	400 ms
Resistance - Initial (Ri) (Min)	35 mOhms	50 mOhms	20 mOhms	35 mOhms
Resistance - Post Trip (R1) (Max)	140 mOhms	140 mOhms	72 mOhms	140 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	1812 (4532 Metric), Concave	1812 (4532 Metric), Concave	1206 (3216 Metric), Concave	1812 (4532 Metric), Concave
Size / Dimension	0.179" L x 0.128" W (4.55mm x 3.24mm)	0.179" L x 0.128" W (4.55mm x 3.24mm)	0.126" L x 0.063" W (3.20mm x 1.59mm)	0.179" L x 0.128" W (4.55mm x 3.24mm)
Thickness (Max)	0.033" (0.85mm)	0.019" (0.48mm)	0.043" (1.10mm)	0.033" (0.85mm)
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	cURus, TUV	CSA, TUV, UL	CSA, TUV, UL	cURus, TUV
Product Status	Active	Active	Active	Active

Engineering Selection Recommendations

MINISMDC125F-2 (Littelfuse miniSMD): Select this direct equivalent when Littelfuse supply chain availability is preferred or when the reduced thickness (0.019" vs. 0.033") provides design advantage for space-constrained applications. Electrical performance is identical to the main part. CSA certification provides additional regulatory coverage beyond cURus and TUV. Moisture sensitivity level 2A (4 Weeks) requires standard handling procedures.

MF-MSMF125-2 (Bourns Multifuse): Select this parametric equivalent when AEC-Q200 automotive qualification is required or when superior moisture sensitivity level (1 vs. 2A) is specified. All electrical parameters and package dimensions match the main part exactly. This option provides design continuity with automotive-grade reliability.

NANOSMDC200F-2 (Littelfuse nanoSMD): Select this similar part only when circuit design permits higher hold current (2A vs. 1.25A) and the smaller 1206 package footprint is compatible with PCB layout. This substitution is not recommended for direct replacement due to different current ratings and package size. Use only when application requirements explicitly allow these parameter changes.

Frequently Asked Questions (FAQ)

Q: Can MINISMDC125F-2 be used as a direct drop-in replacement for PFMF.125.2?

A: Yes. MINISMDC125F-2 provides identical electrical specifications (6V, 1.25A hold, 2.5A trip, 400ms trip time) and the same package footprint (1812/4532 Metric). The reduced thickness (0.019" vs. 0.033") is a physical advantage for compact designs. Initial resistance is slightly higher (50 mOhms vs. 35 mOhms minimum), which remains within acceptable operating parameters.

Q: What are the differences between the three substitute options?

A: MINISMDC125F-2 is a direct electrical equivalent with identical current ratings and trip characteristics. MF-MSMF125-2 is a parametric equivalent offering AEC-Q200 automotive qualification and superior moisture sensitivity. NANOSMDC200F-2 differs in current ratings (2A hold vs. 1.25A) and uses a smaller 1206 package; it is suitable only when higher current capacity is acceptable.

Q: Is NANOSMDC200F-2 compatible with the original design?

A: NANOSMDC200F-2 is not a direct replacement. It has higher hold current (2A vs. 1.25A), different trip current (4A vs. 2.5A), longer trip time (1.5s vs. 400ms), and a smaller package (1206 vs. 1812). Use this part only when circuit design explicitly permits these parameter changes and PCB layout accommodates the smaller footprint.

Q: Which substitute offers the best compliance coverage?

A: MINISMDC125F-2 includes CSA, TUV, and UL certifications, providing broader regulatory coverage than the main part (cURus and TUV). MF-MSMF125-2 maintains cURus and TUV certifications with added AEC-Q200 automotive qualification.

Q: Are all substitutes RoHS3 compliant?

A: Yes. PFMF.125.2, MINISMDC125F-2, NANOSMDC200F-2, and MF-MSMF125-2 are all ROHS3 compliant and REACH unaffected.

Q: What is the impact of different initial resistance values?

A: Initial resistance differences (35 mOhms for PFMF.125.2 and MF-MSMF125-2 vs. 50 mOhms for MINISMDC125F-2) affect circuit behavior during normal operation. The higher value in MINISMDC125F-2 results in slightly increased voltage drop and power dissipation. Both values remain within acceptable limits for 1.25A hold current applications.

Q: Can I use MF-MSMF125-2 in automotive applications?

A: Yes. MF-MSMF125-2 carries AEC-Q200 automotive qualification, making it suitable for automotive-grade designs. The main part (PFMF.125.2) does not list automotive qualification.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message