MICROASMD050F-2 PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The MICROASMD050F-2 is a polymeric PTC resettable fuse manufactured by Littelfuse Inc. in the PolySwitch® microASMD series. This surface mount component is rated for 13.2V maximum voltage with a 500 mA hold current and is housed in a 1210 (3225 Metric) package with concave geometry. The part is active in production and carries AEC-Q200 automotive qualification. PTC resettable fuses are essential protective devices that automatically reset after a fault condition clears, eliminating the need for manual replacement. Identifying equivalent substitute parts ensures design flexibility, supply chain continuity, and access to alternative sourcing options when the primary component becomes unavailable.

Key Parameters

Parameter	Value
Voltage - Max	13.2V
Current - Hold (Ih) (Max)	500 mA
Current - Trip (It)	1 A
Current - Max	40 A
Package / Case	1210 (3225 Metric), Concave
Mounting Type	Surface Mount
Operating Temperature	-40°C ~ 85°C
Ratings	AEC-Q200
Product Status	Active

Substitute Part Grouping Explanation

Substitution of PTC resettable fuses is determined by strict alignment of electrical and mechanical parameters. The MICROASMD050F-2 can be substituted with the PTSA121013V050 based on the following criteria:

Electrical Compatibility:

Voltage rating: Both parts rated at 13.2V maximum
Hold current (Ih): Both rated at 500 mA maximum
Trip current (It): Both rated at 1 A
Maximum current: Both rated at 40 A
Operating temperature range: Both -40°C ~ 85°C

Mechanical Compatibility:

Package type: Both use 1210 (3225 Metric) surface mount package with concave geometry
Mounting: Both are surface mount components

Compliance:

Both parts carry AEC-Q200 automotive qualification

Differences in initial resistance (Ri), post-trip resistance (R1), and time to trip do not prevent substitution when the electrical and mechanical parameters align within the specified tolerances for the application circuit.

Parameter Comparison

Parameter	MICROASMD050F-2 (Littelfuse)	PTSA121013V050 (Eaton)
Manufacturer	Littelfuse Inc.	Eaton - Electronics Division
Series	PolySwitch® microASMD	PTSA1210
Voltage - Max	13.2V	13.2V
Current - Hold (Ih) (Max)	500 mA	500 mA
Current - Trip (It)	1 A	1 A
Current - Max	40 A	40 A
Time to Trip	50 ms	100 ms
Resistance - Initial (Ri) (Min)	250 mOhms	150 mOhms
Resistance - Post Trip (R1) (Max)	900 mOhms	1 Ohms
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C
Ratings	AEC-Q200	AEC-Q200
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)	0.128" L x 0.098" W (3.25mm x 2.50mm)
Thickness (Max)	0.024" (0.62mm)	0.033" (0.85mm)
Moisture Sensitivity Level (MSL)	2A (4 Weeks)	1 (Unlimited)
Product Status	Active	Active

Engineering Selection Recommendations

Both the MICROASMD050F-2 and PTSA121013V050 are active production components with AEC-Q200 automotive qualification, making them suitable for equivalent substitution in applications requiring 13.2V, 500 mA hold current PTC resettable fuses in 1210 surface mount packages.

The MICROASMD050F-2 features a faster trip time of 50 ms compared to the PTSA121013V050 at 100 ms. The MICROASMD050F-2 also has lower initial resistance (250 mOhms minimum) and lower post-trip resistance (900 mOhms maximum) relative to the PTSA121013V050 (150 mOhms minimum initial, 1 Ohm maximum post-trip).

The PTSA121013V050 offers superior moisture handling with MSL 1 (Unlimited) compared to the MICROASMD050F-2 MSL 2A (4 Weeks), and includes UL approval certification.

Selection between these parts should be based on specific application requirements regarding trip response time, resistance characteristics, and environmental moisture exposure conditions.

Frequently Asked Questions (FAQ)

Q: Can the PTSA121013V050 be used as a direct replacement for the MICROASMD050F-2?

A: Yes, the PTSA121013V050 is electrically and mechanically compatible as a substitute. Both parts share identical voltage ratings (13.2V), hold current (500 mA), trip current (1 A), maximum current (40 A), operating temperature range (-40°C ~ 85°C), and package geometry (1210 Concave surface mount). Both carry AEC-Q200 qualification.

Q: What are the key differences between these two parts?

A: The primary differences are trip response time (MICROASMD050F-2: 50 ms vs. PTSA121013V050: 100 ms), initial resistance values, post-trip resistance characteristics, package thickness (0.62mm vs. 0.85mm), and moisture sensitivity rating (MSL 2A vs. MSL 1).

Q: Are there any package compatibility concerns?

A: Both parts use the 1210 (3225 Metric) surface mount package with concave geometry. Dimensional variations are minimal (length 3.22mm vs. 3.25mm, width 2.58mm vs. 2.50mm). The PTSA121013V050 has greater thickness (0.85mm vs. 0.62mm), which should be verified against PCB assembly clearance requirements.

Q: Do both parts meet automotive standards?

A: Yes, both the MICROASMD050F-2 and PTSA121013V050 carry AEC-Q200 automotive qualification ratings.

Q: Which part should be selected for high-moisture environments?

A: The PTSA121013V050 is rated MSL 1 (Unlimited moisture sensitivity level) compared to the MICROASMD050F-2 MSL 2A (4 Weeks), making it more suitable for applications with extended exposure to humid conditions.

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