MF-SM300-2-99 Equivalent & Substitute Parts

Part Overview

The MF-SM300-2-99 is a Polymeric PTC Resettable Fuse manufactured by Bourns Inc. as part of the Multifuse® MF-SM series. This component is rated for 6V maximum voltage with a 3A hold current and is designed for surface mount applications in 2-SMD package configuration. The part is currently listed as obsolete, making identification of suitable substitutes essential for ongoing design support and component procurement.

Key Parameters

Parameter	Value
Voltage - Max	6V
Current - Hold (Ih) (Max)	3 A
Current - Trip (It)	6 A
Current - Max	100 A
Time to Trip	35 s
Resistance - Initial (Ri) (Min)	15 mOhms
Resistance - Post Trip (R1) (Max)	48 mOhms
Operating Temperature	-40°C ~ 85°C
Package / Case	2-SMD
Size / Dimension	0.287" L x 0.214" W (7.31mm x 5.44mm)
Thickness (Max)	0.118" (3.00mm)
Mounting Type	Surface Mount
Ratings	AEC-Q200
Approval Agency	cURus, TUV
RoHS Status	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the MF-SM300-2-99 is determined by strict equivalence across the following critical parameters:

Voltage rating: 6V maximum
Hold current (Ih): 3A maximum
Trip current (It): 6A
Time to trip: 35 seconds
Initial resistance (Ri): 15 mOhms minimum
Post-trip resistance (R1): 48 mOhms maximum
Package configuration: 2-SMD surface mount
Physical dimensions: 0.287" L x 0.214" W x 0.118" maximum thickness
Operating temperature range: -40°C to 85°C
Regulatory compliance: AEC-Q200, cURus, TUV approval

The MF-SM300-2 qualifies as a parametric equivalent substitute based on identical electrical specifications and mechanical compatibility across all listed parameters.

Parameter Comparison

Parameter	MF-SM300-2-99 (Main Part)	MF-SM300-2 (Substitute)	Match Status
Voltage - Max	6V	6V	Identical
Current - Hold (Ih) (Max)	3 A	3 A	Identical
Current - Trip (It)	6 A	6 A	Identical
Current - Max	100 A	100 A	Identical
Time to Trip	35 s	35 s	Identical
Resistance - Initial (Ri) (Min)	15 mOhms	15 mOhms	Identical
Resistance - Post Trip (R1) (Max)	48 mOhms	48 mOhms	Identical
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	Identical
Package / Case	2-SMD	2-SMD	Identical
Size / Dimension	0.287" L x 0.214" W (7.31mm x 5.44mm)	0.287" L x 0.214" W (7.31mm x 5.44mm)	Identical
Thickness (Max)	0.118" (3.00mm)	0.118" (3.00mm)	Identical
Mounting Type	Surface Mount	Surface Mount	Identical
Ratings	AEC-Q200	AEC-Q200	Identical
Approval Agency	cURus, TUV	cURus, TUV	Identical
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	Identical
Product Status	Obsolete	Active	Substitute is active
Packaging	Bulk	Tape & Reel (TR)	Different format

Engineering Selection Recommendations

The MF-SM300-2 is a direct parametric equivalent to the obsolete MF-SM300-2-99. All electrical characteristics, mechanical dimensions, and regulatory certifications are identical. The primary distinction is product status: MF-SM300-2-99 is obsolete while MF-SM300-2 maintains active production status.

The MF-SM300-2 carries identical AEC-Q200 automotive qualification and maintains cURus and TUV approvals. ROHS3 compliance and MSL rating are preserved. The substitute is available in Tape & Reel packaging format, which is standard for active production components.

For applications requiring the MF-SM300-2-99 specification, the MF-SM300-2 provides full functional and mechanical compatibility without design modification.

Frequently Asked Questions (FAQ)

Q: Can MF-SM300-2 be used as a direct replacement for MF-SM300-2-99?

A: Yes. All electrical parameters, mechanical dimensions, and regulatory certifications are identical. The MF-SM300-2 is the active production equivalent of the obsolete MF-SM300-2-99.

Q: What is the difference between MF-SM300-2-99 and MF-SM300-2?

A: The MF-SM300-2-99 is obsolete; MF-SM300-2 is the active equivalent. Packaging differs (bulk versus Tape & Reel), but electrical and mechanical specifications are identical.

Q: Are there any thermal or electrical performance differences?

A: No. Both parts share identical voltage ratings (6V), hold current (3A), trip current (6A), resistance characteristics, and operating temperature range (-40°C to 85°C).

Q: Is the 2-SMD package compatible with existing PCB layouts?

A: Yes. Both parts use identical 2-SMD surface mount package with dimensions of 0.287" L x 0.214" W x 0.118" maximum thickness. No PCB redesign is required.

Q: Are automotive certifications maintained?

A: Yes. Both parts carry AEC-Q200 qualification and cURus and TUV approvals. ROHS3 compliance is maintained.

Q: What packaging format is available for MF-SM300-2?

A: MF-SM300-2 is supplied in Tape & Reel (TR) format, standard for active production components.

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