MF-USML450-2 PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The MF-USML450-2 is a polymeric PTC resettable fuse manufactured by Bourns Inc., designed for surface mount applications in the 1210 (3225 Metric) package. This component provides overcurrent protection with a 6V maximum voltage rating and 4.5A hold current specification. The MF-USML450-2 is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and component procurement.

Key Parameters

Parameter	Value
Manufacturer	Bourns Inc.
Series	Multifuse®, MF-USML
Voltage - Max	6V
Current - Hold (Ih) (Max)	4.5 A
Current - Trip (It)	9 A
Current - Max	50 A
Time to Trip	2 s
Operating Temperature	-40°C ~ 85°C
Package / Case	1210 (3225 Metric), Concave
Mounting Type	Surface Mount
RoHS Status	ROHS3 Compliant
Approval Agency	cURus, TUV

Substitute Part Grouping Explanation

Substitution eligibility for the MF-USML450-2 is determined by the following critical parameters:

Voltage rating: 6V maximum
Current hold specification: 4.5A
Current trip specification: 9A
Package configuration: 1210 (3225 Metric), Concave
Mounting type: Surface Mount
Operating temperature range: -40°C ~ 85°C
Regulatory compliance: cURus, TUV approval; ROHS3 compliance

The MF-USML450/6-2 meets all substitution criteria as a direct equivalent within the Multifuse® product family, with identical electrical performance specifications and package geometry.

Parameter Comparison

Parameter	MF-USML450-2	MF-USML450/6-2
Manufacturer	Bourns Inc.	Bourns Inc.
Series	Multifuse®, MF-USML	Multifuse®, MF-USML/X
Product Status	Obsolete	Active
Type	Polymeric	Polymeric
Voltage - Max	6V	6V
Current - Hold (Ih) (Max)	4.5 A	4.5 A
Current - Trip (It)	9 A	9 A
Current - Max	50 A	50 A
Time to Trip	2 s	2 s
Resistance - Initial (Ri) (Min)	1 mOhms	2 mOhms
Resistance - Post Trip (R1) (Max)	15 mOhms	14 mOhms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C
Mounting Type	Surface Mount	Surface Mount
Package / Case	1210 (3225 Metric), Concave	1210 (3225 Metric), Concave
Size / Dimension	0.127" L x 0.102" W (3.22mm x 2.58mm)	0.127" L x 0.101" W (3.22mm x 2.58mm)
Thickness (Max)	0.047" (1.20mm)	0.047" (1.20mm)
Approval Agency	cURus, TUV	cURus, TUV
RoHS Status	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	2A (4 Weeks)	2A (4 Weeks)
REACH Status	REACH Unaffected	REACH Unaffected
ECCN	EAR99	EAR99
HTSUS	8533.40.8070	8533.40.8070

Engineering Selection Recommendations

The MF-USML450/6-2 is the direct substitute for the obsolete MF-USML450-2. Both components share identical electrical specifications, package geometry, and regulatory certifications. The MF-USML450/6-2 carries active product status from Bourns Inc., ensuring ongoing availability and manufacturing support.

Selection of the MF-USML450/6-2 is appropriate for applications requiring direct replacement of the MF-USML450-2 without circuit redesign. Both components maintain cURus and TUV approval certifications and comply with ROHS3 requirements. The minor variations in initial resistance (1 mOhms vs. 2 mOhms) and post-trip resistance (15 mOhms vs. 14 mOhms) remain within acceptable tolerance ranges for polymeric PTC fuse applications.

Frequently Asked Questions (FAQ)

Q: Can the MF-USML450/6-2 be used as a direct replacement for the MF-USML450-2?

A: Yes. Both components share identical voltage ratings (6V), current hold specifications (4.5A), current trip specifications (9A), package configurations (1210 Concave), and operating temperature ranges (-40°C ~ 85°C). The MF-USML450/6-2 is the active equivalent.

Q: What is the difference between the MF-USML450-2 and MF-USML450/6-2?

A: The primary difference is product status: MF-USML450-2 is obsolete, while MF-USML450/6-2 is active. Minor variations exist in initial resistance (1 mOhms vs. 2 mOhms) and post-trip resistance (15 mOhms vs. 14 mOhms). Electrical performance and package specifications remain functionally equivalent.

Q: Are there packaging differences between these parts?

A: The MF-USML450-2 is supplied in standard packaging, while the MF-USML450/6-2 is available in Tape & Reel (TR) format. Both maintain identical physical dimensions and mounting characteristics for surface mount applications.

Q: Do both parts carry the same regulatory approvals?

A: Yes. Both the MF-USML450-2 and MF-USML450/6-2 carry cURus and TUV approvals, comply with ROHS3 requirements, and maintain REACH Unaffected status.

Q: What is the moisture sensitivity level for these components?

A: Both components are classified as MSL 2A (4 Weeks), indicating standard moisture sensitivity handling requirements for surface mount components.

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