MF-USMF050-2 Equivalent & Substitute Parts

Part Overview

The MF-USMF050-2 is a Polymeric PTC Resettable Fuse manufactured by Bourns Inc. in the Multifuse® series. This surface mount component operates at 13.2V with a 500 mA hold current and is housed in a 1210 (3225 Metric) package with concave geometry. The part is Active status and ROHS3 compliant with AEC-Q200 ratings. Equivalent and substitute parts are identified to support procurement flexibility, inventory management, and supply chain continuity for applications requiring polymeric PTC resettable fuse functionality in this voltage and current class.

Key Parameters

Parameter	Value
Voltage - Max	13.2V
Current - Hold (Ih) (Max)	500 mA
Current - Trip (It)	1 A
Package / Case	1210 (3225 Metric), Concave
Mounting Type	Surface Mount
Operating Temperature	-40°C ~ 85°C
Type	Polymeric
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitute parts for the MF-USMF050-2 are classified based on electrical parameter compatibility and mechanical interchangeability. The primary substitution criteria are:

Direct Equivalents maintain identical or functionally equivalent electrical specifications: 13.2V maximum voltage, 500 mA hold current, 1 A trip current, and 1210 (3225 Metric) concave package geometry. These parts are mechanically and electrically interchangeable without circuit redesign.

Similar Alternatives share the same voltage and current ratings but may differ in secondary parameters such as initial resistance, post-trip resistance, or time-to-trip characteristics. These parts require engineering review to confirm suitability for specific application requirements.

The following substitute parts meet the core substitution criteria for the MF-USMF050-2:

MICROSMD050F-2 (Littelfuse Inc., Direct Equivalent)
1210L050YR (Littelfuse Inc., Similar Alternative)
PTSA121013V050 (Eaton - Electronics Division, Similar Alternative)

The MICROSMD010F-2 (Littelfuse Inc.) operates at 30V with 100 mA hold current and is not electrically equivalent; it is listed for reference only and is not recommended as a substitute.

Parameter Comparison

Parameter	MF-USMF050-2	MICROSMD050F-2	1210L050YR	PTSA121013V050
Manufacturer	Bourns Inc.	Littelfuse Inc.	Littelfuse Inc.	Eaton - Electronics Division
Series	Multifuse®, MF-USMF	PolySwitch®, microSMD	POLY-FUSE®, 1210L	PTSA1210
Voltage - Max	13.2V	13.2V	13.2V	13.2V
Current - Hold (Ih) (Max)	500 mA	500 mA	500 mA	500 mA
Current - Trip (It)	1 A	1 A	1 A	1 A
Current - Max	40 A	40 A	100 A	40 A
Time to Trip	100 ms	50 ms	50 ms	100 ms
Resistance - Initial (Ri) (Min)	180 mOhms	250 mOhms	250 mOhms	150 mOhms
Resistance - Post Trip (R1) (Max)	900 mOhms	900 mOhms	900 mOhms	1 Ohms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C	-40°C ~ 85°C
Package / Case	1210 (3225 Metric), Concave	1210 (3225 Metric), Concave	1210 (3225 Metric), Concave	1210 (3225 Metric), Concave
Thickness (Max)	0.033" (0.85mm)	0.024" (0.62mm)	0.033" (0.85mm)	0.033" (0.85mm)
Mounting Type	Surface Mount	Surface Mount	Surface Mount	Surface Mount
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Ratings	AEC-Q200	-	-	AEC-Q200
Approval Agency	cURus, TUV	CSA, TUV, UL	cURus, TUV	UL
Moisture Sensitivity Level (MSL)	1 (Unlimited)	2A (4 Weeks)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

MICROSMD050F-2 is a direct electrical equivalent with identical voltage, hold current, and trip current specifications. This part is ROHS3 compliant and carries CSA, TUV, and UL approvals. The primary consideration is the reduced thickness (0.024" vs. 0.033") and MSL rating of 2A (4 Weeks) compared to the original part's MSL 1 (Unlimited). This part is suitable for applications where the thinner profile is compatible with PCB assembly constraints and moisture handling procedures support the 4-week MSL requirement.

1210L050YR is electrically equivalent with identical voltage, hold current, and trip current specifications. This part carries the same approval agencies (cURus, TUV) as the original and maintains MSL 1 (Unlimited) rating. The maximum current rating is higher at 100 A versus 40 A, which does not affect substitution suitability. This part is suitable for direct replacement in applications requiring AEC-Q200 equivalent performance and unlimited moisture sensitivity handling.

PTSA121013V050 is electrically equivalent with identical voltage, hold current, and trip current specifications. This part carries AEC-Q200 ratings matching the original part and maintains MSL 1 (Unlimited) rating. The post-trip resistance is specified at 1 Ohms maximum versus 900 mOhms for the original part, which represents a minor increase in post-trip impedance. This part is suitable for applications where AEC-Q200 compliance is required and the slightly higher post-trip resistance is acceptable.

Frequently Asked Questions (FAQ)

Q: Can MICROSMD050F-2 be used as a direct replacement for MF-USMF050-2?

A: MICROSMD050F-2 is electrically equivalent with matching voltage (13.2V), hold current (500 mA), and trip current (1 A) specifications. The primary difference is the reduced thickness (0.024" vs. 0.033") and MSL rating of 2A (4 Weeks). Substitution is permissible if PCB assembly design accommodates the thinner profile and moisture handling procedures comply with the 4-week MSL requirement.

Q: What is the difference between the time-to-trip values in the substitute parts?

A: The MF-USMF050-2 specifies 100 ms time-to-trip, while MICROSMD050F-2 and 1210L050YR specify 50 ms. PTSA121013V050 matches the original at 100 ms. Time-to-trip is the duration required for the fuse to transition from normal state to tripped state under fault conditions. Applications with specific timing requirements should select parts with matching time-to-trip specifications.

Q: Are all substitute parts ROHS3 compliant?

A: Yes, all listed substitute parts (MICROSMD050F-2, 1210L050YR, and PTSA121013V050) are ROHS3 compliant, matching the original MF-USMF050-2 specification.

Q: What is the significance of the MSL (Moisture Sensitivity Level) rating difference?

A: The original MF-USMF050-2 carries MSL 1 (Unlimited), meaning it can be stored indefinitely without moisture control. MICROSMD050F-2 carries MSL 2A (4 Weeks), requiring controlled storage conditions and limiting shelf life to 4 weeks after packaging opening. Selection depends on supply chain logistics and storage capabilities. Parts with MSL 1 rating offer greater flexibility in inventory management.

Q: Can MICROSMD010F-2 be used as a substitute?

A: No. MICROSMD010F-2 operates at 30V with 100 mA hold current, which differs significantly from the MF-USMF050-2 specification of 13.2V and 500 mA. This part is not electrically equivalent and is not suitable for substitution.

Q: What approval agencies are represented across the substitute parts?

A: MICROSMD050F-2 carries CSA, TUV, and UL approvals. 1210L050YR carries cURus and TUV approvals. PTSA121013V050 carries UL approval. The original MF-USMF050-2 carries cURus and TUV approvals. Selection should consider application-specific regulatory requirements and regional approval standards.

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