SS15FA Schottky Diode Equivalent & Substitute Parts

Part Overview

The SS15FA is a Schottky rectifier diode manufactured by onsemi, rated for 50V DC reverse voltage and 1A average rectified current in a surface mount SOD-123FA package. This component is classified as "Not For New Designs," indicating it has reached end-of-life status. The part carries automotive-grade qualification (AEC-Q101) and is ROHS3 compliant. Due to its discontinued design status, identifying functionally compatible substitute components is essential for ongoing production support, maintenance applications, and legacy system repairs.

Substiute Parts

SS15FA

onsemiIn Stock: 23213SS15FA Datasheet

Current PartRFQ

V1FM15-M3/H

Vishay General Semiconductor - Diodes DivisionIn Stock: 11866V1FM15-M3/H Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the SS15FA requires strict adherence to the following electrical and mechanical criteria:

Primary Substitution Criteria:

• Technology: Schottky diode
• Mounting Type: Surface Mount
• Current Rating: Minimum 1A average rectified current
• Voltage Rating: Minimum 50V DC reverse voltage (equal or higher)
• Speed Classification: Fast Recovery ≤ 500ns, > 200mA (Io)
• Temperature Range: Operating junction temperature must encompass or exceed -55°C to 150°C
• Compliance: ROHS3 compliant, AEC-Q101 automotive qualification preferred

Package Compatibility Consideration: The SS15FA uses SOD-123W package. Substitute parts may use equivalent surface mount packages (such as DO-219AB/SMF) provided the physical footprint and lead configuration are compatible with the target PCB design.

The identified substitute V1FM15-M3/H meets all primary electrical criteria with higher voltage rating (150V) and maintains fast recovery speed classification. This part is in Active product status, ensuring long-term availability.

Parameter Comparison

Engineering Selection Recommendations

Substitution Feasibility:

The V1FM15-M3/H is electrically suitable as a substitute for the SS15FA based on the following factors:

1. Voltage Rating: The 150V rating of the V1FM15-M3/H exceeds the 50V requirement of the SS15FA, providing margin for transient overvoltage conditions common in automotive and industrial applications.

2. Current Rating: Both parts are rated for 1A average rectified current, ensuring equivalent current-handling capability.

3. Speed Classification: Both parts meet the fast recovery specification (≤ 500ns, > 200mA), maintaining switching performance in rectification circuits.

4. Compliance Status: The V1FM15-M3/H is ROHS3 compliant and carries AEC-Q101 automotive qualification, matching the regulatory requirements of the original part.

5. Product Availability: The V1FM15-M3/H is in Active product status with documented inventory, ensuring supply chain continuity compared to the discontinued SS15FA.

Design Considerations:

• Forward Voltage Drop: The V1FM15-M3/H exhibits a higher forward voltage drop (1.22V vs. 700mV at 1A). Circuit designs sensitive to voltage drop magnitude must account for this 520mV difference in power dissipation calculations.

• Package Transition: The change from SOD-123W to DO-219AB (SMF) requires PCB footprint verification. Physical dimensions and lead spacing differ between these packages.

• Temperature Range: The lower minimum operating temperature of the V1FM15-M3/H (-40°C vs. -55°C) may be a constraint in extreme cold-weather applications.

Frequently Asked Questions (FAQ)

Q1: Can the V1FM15-M3/H directly replace the SS15FA without PCB modification?

A: Electrical substitution is valid. However, the package change from SOD-123W to DO-219AB (SMF) requires PCB footprint compatibility verification. Physical land pattern, lead pitch, and solder pad dimensions must be confirmed before implementation.

Q2: Why is the forward voltage drop of the V1FM15-M3/H higher than the SS15FA?

A: Forward voltage drop is a characteristic of Schottky diode construction and material properties. The V1FM15-M3/H's higher rating (150V vs. 50V) and different semiconductor junction design result in increased forward voltage. This is a normal trade-off in higher-voltage Schottky devices.

Q3: Does the higher voltage rating (150V) of the V1FM15-M3/H affect circuit performance in a 50V application?

A: No. A higher voltage-rated diode operates correctly in lower-voltage circuits. The 150V rating provides additional safety margin against transient overvoltages. The diode will conduct at the same forward voltage threshold and exhibit the same rectification behavior.

Q4: What is the impact of the -40°C minimum temperature limit of the V1FM15-M3/H compared to the SS15FA's -55°C?

A: If the application requires operation below -40°C, the V1FM15-M3/H is not suitable. For applications with minimum operating temperatures at or above -40°C, this difference is not a constraint.

Q5: Are there package footprint compatibility issues between SOD-123W and DO-219AB?

A: Yes. These are distinct surface mount packages with different physical dimensions. SOD-123W and DO-219AB (SMF) have different lead spacing and pad layouts. PCB design files must be reviewed and potentially modified to accommodate the DO-219AB footprint.

Q6: Is the V1FM15-M3/H suitable for automotive applications?

A: Yes. The V1FM15-M3/H carries AEC-Q101 automotive qualification and is ROHS3 compliant, meeting automotive industry standards for component reliability and environmental compliance.

Q7: What is the significance of the lower reverse leakage current in the V1FM15-M3/H?

A: Lower reverse leakage (50µA @ 150V vs. 400µA @ 50V) indicates reduced parasitic current flow when the diode is reverse-biased. This characteristic improves circuit efficiency and reduces power dissipation in standby or blocking conditions.