MF-R040-2 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The MF-R040-2 is a Polymeric PTC Resettable Fuse manufactured by Bourns Inc. under the Multifuse® MF-R series. This through-hole radial disc component is rated for 60V maximum voltage with a 400 mA hold current and is designed for circuit protection applications requiring automatic reset capability. The part maintains Active product status with full RoHS3 compliance and unlimited moisture sensitivity rating. Substitute parts are identified when equivalent electrical performance and mechanical compatibility are required due to inventory constraints, supply chain considerations, or design flexibility needs.

Substiute Parts

MF-R040-2

Bourns Inc.In Stock: 1873MF-R040-2 Datasheet

Current PartRFQ

RXEF017-AP

LittelfuseIn Stock: 1385RXEF017-AP Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MF-R040-2 is determined by the following critical parameters:

• Voltage Rating: Maximum voltage must equal or exceed 60V
• Mounting Configuration: Through-hole radial disc package required for PCB compatibility
• Physical Dimensions: Lead spacing and overall form factor must accommodate existing PCB layouts
• Operating Temperature Range: Must support -40°C to 85°C operational envelope
• Regulatory Compliance: RoHS3 compliance and recognized approval agencies (cURus, TUV, CSA, UL, CQC) required

The RXEF017-AP from Littelfuse meets these substitution criteria. However, the hold current (Ih) specification differs: MF-R040-2 provides 400 mA while RXEF017-AP provides 170 mA. This difference affects circuit protection thresholds and must be evaluated against specific application requirements.

Parameter Comparison

Engineering Selection Recommendations

Both the MF-R040-2 and RXEF017-AP maintain Active product status with full RoHS3 compliance and unlimited moisture sensitivity ratings. The RXEF017-AP carries additional regulatory approvals (CSA, UL, CQC) beyond the MF-R040-2 certifications (cURus, TUV).

Selection between these components must be based on circuit protection requirements. The MF-R040-2 provides a 400 mA hold current threshold, while the RXEF017-AP operates at 170 mA. Applications requiring the higher 400 mA threshold must use the MF-R040-2. Applications with lower current protection requirements or those benefiting from the broader certification scope of the RXEF017-AP may utilize the substitute part.

Physical compatibility is confirmed: both components feature radial disc through-hole packages with equivalent lead spacing and minimal dimensional variation that does not impact PCB layout or assembly processes.

Frequently Asked Questions (FAQ)

Q: Can RXEF017-AP directly replace MF-R040-2 in all applications?

A: Physical and electrical compatibility exists for voltage rating, operating temperature, and mounting configuration. However, the hold current differs significantly (170 mA vs. 400 mA). Direct replacement is only appropriate for circuits where the lower 170 mA protection threshold is acceptable.

Q: What is the significance of the hold current (Ih) difference?

A: Hold current defines the maximum continuous current the fuse allows without tripping. The MF-R040-2 permits 400 mA continuous operation, while RXEF017-AP permits 170 mA. Circuits designed for 400 mA operation may experience nuisance trips if the RXEF017-AP is substituted.

Q: Are the physical dimensions compatible with existing PCB layouts?

A: Yes. Both components use 0.291" diameter radial disc packages with lead spacing of approximately 5.1mm. The thickness variation (0.122" vs. 0.118") is negligible and does not affect PCB routing or component clearance.

Q: Which certifications apply to each part?

A: MF-R040-2 carries cURus and TUV approvals. RXEF017-AP carries CQC, CSA, TUV, and UL approvals. Both maintain RoHS3 compliance and REACH unaffected status.

Q: What is the trip current difference between these parts?

A: MF-R040-2 trips at 800 mA, while RXEF017-AP trips at 340 mA. This represents a significant difference in fault protection response and must align with circuit design specifications.