MICROASMDCH125F-2 Polymeric PTC Resettable Fuse Equivalent & Substitute Parts

Part Overview

The MICROASMDCH125F-2 is a Polymeric PTC Resettable Fuse manufactured by Littelfuse Inc. in the PolySwitch® microASMD series. This component functions as an overcurrent protection device with a hold current of 1.25 A and trip current of 3.75 A, designed for 12V applications in surface mount configurations. The part maintains Active product status and is available in standard Tape & Reel packaging with 3866 pieces in current inventory. Identification of equivalent and substitute components becomes necessary when addressing supply chain requirements, design revisions, or inventory optimization while maintaining identical electrical and mechanical performance characteristics.

Substiute Parts

MICROASMDCH125F-2

Littelfuse Inc.In Stock: 3925MICROASMDCH125F-2 Datasheet

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MICROASMDCH125F-2

Littelfuse Inc.In Stock: 3925MICROASMDCH125F-2 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the MICROASMDCH125F-2 is determined by strict equivalence across all critical electrical and mechanical parameters. The following parameters establish the substitution criteria:

Electrical Parameters:

• Voltage rating of 12V maximum
• Hold current (Ih) of 1.25 A maximum
• Trip current (It) of 3.75 A
• Initial resistance (Ri) minimum of 30 mOhms
• Post-trip resistance (R1) maximum of 300 mOhms
• Time to trip of 1 second
• Maximum current capacity of 40 A

Mechanical Parameters:

• Surface mount mounting type
• 1210 (3225 Metric) package with concave configuration
• Physical dimensions of 0.127" L x 0.101" W (3.22mm x 2.58mm)
• Maximum thickness of 0.055" (1.40mm)

Compliance Parameters:

• Polymeric PTC type classification
• AEC-Q200 automotive qualification
• TUV and UR approval agencies
• Moisture Sensitivity Level 2A (4 Weeks)

Only components matching all specified parameters across these three categories qualify as direct substitutes.

Parameter Comparison

Engineering Selection Recommendations

The MICROASMDCH125F-2 maintains Active product status with full compliance to automotive qualification standards through AEC-Q200 certification. The component carries dual approval from TUV and UR agencies, confirming suitability for regulated applications. The Tape & Reel packaging format supports automated assembly processes with standard moisture handling protocols at MSL 2A classification.

Selection of substitute components must maintain identical electrical performance across all current and resistance parameters to ensure circuit protection integrity. The 1210 (3225 Metric) surface mount package with concave configuration requires PCB layout compatibility verification. Operating temperature range of -40°C to 85°C establishes the thermal envelope for application deployment.

Direct substitution is limited to components matching all specified parameters without deviation. The polymeric PTC technology classification and 1-second trip time characteristic define the protection response profile for the protected circuit.

Frequently Asked Questions (FAQ)

Q: What electrical parameters must match for a valid substitute of the MICROASMDCH125F-2?

A: The substitute must maintain identical voltage rating (12V), hold current (1.25 A), trip current (3.75 A), initial resistance (30 mOhms minimum), post-trip resistance (300 mOhms maximum), and trip time (1 second). Deviation in any electrical parameter disqualifies the component as a direct substitute.

Q: Are there mechanical compatibility requirements for substitution?

A: Yes. The substitute must use surface mount technology with 1210 (3225 Metric) package configuration in concave form. Physical dimensions of 0.127" L x 0.101" W (3.22mm x 2.58mm) and maximum thickness of 0.055" (1.40mm) must be maintained for PCB footprint compatibility.

Q: What compliance certifications are required for substitution?

A: The substitute must carry AEC-Q200 automotive qualification and approval from both TUV and UR agencies. These certifications confirm suitability for regulated applications and cannot be omitted.

Q: Does the packaging format affect substitution eligibility?

A: Yes. The component must be supplied in Tape & Reel (TR) format with Moisture Sensitivity Level 2A (4 Weeks) classification. Alternative packaging formats are not acceptable substitutes.

Q: Can components from different manufacturers substitute for the MICROASMDCH125F-2?

A: Only components that match all electrical, mechanical, and compliance parameters across identical specifications qualify as substitutes. Manufacturer identity is not the determining factor; parameter equivalence is the sole criterion.

Q: What is the significance of the polymeric PTC type classification?

A: The polymeric PTC (Positive Temperature Coefficient) technology defines the protection mechanism and thermal response characteristics. Substitutes must use identical polymeric PTC technology to maintain circuit protection performance.

Q: How does the 1-second trip time affect circuit design?

A: The 1-second trip time establishes the response latency for overcurrent detection and protection activation. This parameter must remain constant in substitutes to preserve circuit protection timing and prevent nuisance trips or delayed protection.