FDG315N Equivalent & Substitute Parts

Part Overview

The FDG315N is an N-Channel MOSFET manufactured by onsemi, rated for 30V drain-to-source voltage with 2A continuous drain current at 25°C. The device is housed in a 6-pin SC-88 (SC-70-6) surface mount package and dissipates up to 750mW. This part is classified as obsolete, making identification of equivalent and substitute components necessary for ongoing design support, production continuity, and system maintenance.

Substiute Parts

FDG315N

onsemiIn Stock: 24388FDG315N Datasheet

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AO7412

Alpha & Omega Semiconductor Inc.In Stock: 12354AO7412 Datasheet

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SI1404BDH-T1-GE3

Vishay SiliconixIn Stock: 10085SI1404BDH-T1-GE3 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the FDG315N is determined by strict equivalence in the following electrical and mechanical parameters:

Critical Matching Parameters:

• Drain-to-Source Voltage (Vdss): 30V minimum
• FET Type: N-Channel
• Technology: MOSFET (Metal Oxide)
• Package Type: SC-88 (SC-70-6) or compatible 6-pin surface mount
• Operating Temperature Range: -55°C to 150°C minimum
• RoHS3 Compliance and MSL Level 1 rating

Performance Considerations:

• Continuous Drain Current (Id): Substitute must support minimum 2A at 25°C or higher
• On-Resistance (Rds On): Lower values indicate improved performance; substitutes with equal or lower Rds On are functionally compatible
• Power Dissipation: Substitutes must handle thermal requirements of the application
• Gate Threshold Voltage: Must fall within acceptable switching characteristics for the circuit

The substitute parts listed below meet or exceed the critical electrical specifications and package requirements of the FDG315N while maintaining active product status or equivalent compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

AO7412 (Alpha & Omega Semiconductor Inc.): The AO7412 is an active product offering 30V Vdss rating with 1.7A continuous drain current. This substitute provides lower on-resistance (90 mOhm) compared to the FDG315N (120 mOhm), resulting in reduced power dissipation and improved thermal performance. The lower gate threshold voltage (1.8V vs. 3V) enables faster switching response. The AO7412 maintains full RoHS3 compliance, MSL Level 1 rating, and identical operating temperature range. The reduced power dissipation rating (350 mW vs. 750 mW) indicates this device is suitable for applications where thermal constraints are less demanding. Package compatibility is confirmed through SC-70-6 designation.

SI1404BDH-T1-GE3 (Vishay Siliconix): The SI1404BDH-T1-GE3 is an active TrenchFET® product rated for 30V Vdss with 1.9A continuous drain current at 25°C and 2.37A at case temperature. This substitute provides significantly higher power dissipation capability (1.32W at Ta, 2.28W at Tc) compared to the FDG315N, making it suitable for higher-power applications. The lower gate threshold voltage (1.3V) and reduced gate charge (2.7 nC) support faster switching characteristics. Input capacitance is substantially lower (100 pF vs. 220 pF), reducing switching losses. The SI1404BDH-T1-GE3 maintains full RoHS3 compliance, MSL Level 1 rating, and identical operating temperature range. Package compatibility is confirmed through SC-70-6 designation.

Both substitute parts are active products with established supply chains, providing superior long-term availability compared to the obsolete FDG315N. Selection between substitutes depends on application current requirements and thermal management needs.

Frequently Asked Questions (FAQ)

Q: Can the AO7412 directly replace the FDG315N in all applications?

A: The AO7412 is electrically compatible with the FDG315N for applications requiring up to 1.7A continuous drain current at 25°C. Applications designed for the full 2A rating of the FDG315N require evaluation of actual current draw. The lower on-resistance of the AO7412 (90 mOhm vs. 120 mOhm) provides improved performance. The reduced power dissipation rating (350 mW vs. 750 mW) indicates thermal design differences; verify that application thermal requirements do not exceed the AO7412 specification.

Q: What are the key differences between the AO7412 and SI1404BDH-T1-GE3?

A: Both devices share 30V Vdss rating and SC-70-6 package compatibility. The SI1404BDH-T1-GE3 provides higher continuous drain current (1.9A at Ta, 2.37A at Tc) and significantly higher power dissipation capability (1.32W at Ta vs. 350 mW for AO7412). The SI1404BDH-T1-GE3 features lower input capacitance (100 pF vs. 270 pF), reducing switching losses. The AO7412 offers lower on-resistance (90 mOhm vs. 238 mOhm at 4.5V), resulting in lower conduction losses at high current. Selection depends on whether the application is current-limited or power-dissipation-limited.

Q: Are all substitute parts available in the same package as the FDG315N?

A: The FDG315N is specified in SC-88 (SC-70-6) package. Both substitute parts are specified in SC-70-6 package, which is mechanically and electrically compatible. Verify PCB footprint compatibility before design implementation, as minor variations in lead spacing or pad dimensions may exist between manufacturers.

Q: Do the substitute parts meet the same compliance requirements as the FDG315N?

A: Yes. Both AO7412 and SI1404BDH-T1-GE3 are ROHS3 compliant with MSL Level 1 (Unlimited) moisture sensitivity rating, matching the FDG315N specifications. Both are REACH Unaffected and classified under ECCN EAR99, providing equivalent regulatory compliance for most applications.

Q: What is the impact of different gate threshold voltages on circuit operation?

A: The FDG315N has a gate threshold voltage of 3V at 250µA, while AO7412 is 1.8V and SI1404BDH-T1-GE3 is 1.3V. Lower threshold voltages enable switching at lower gate drive voltages, potentially improving switching speed and reducing gate drive power requirements. Circuits designed with gate drive voltages significantly above 3V will operate the substitute parts in a more heavily saturated state, which may affect switching characteristics. Verify gate drive voltage compatibility with the selected substitute.

Q: How do the on-resistance specifications affect power dissipation?

A: On-resistance directly determines conduction losses through the formula P = I²R. The FDG315N at 120 mOhm dissipates 240 mW at 2A continuous current. The AO7412 at 90 mOhm dissipates 153 mW at 1.7A, and the SI1404BDH-T1-GE3 at 238 mOhm (measured at 4.5V) dissipates approximately 86 mW at 1.9A. Lower on-resistance reduces thermal load and improves efficiency, but actual dissipation depends on circuit operating current and duty cycle.

Q: Is the FDG315N still available despite obsolete status?

A: The FDG315N is listed with 24,367 pieces in stock as new original inventory. Obsolete status indicates the manufacturer has discontinued production and will not accept new orders. Existing inventory from authorized distributors remains available for a limited period. For new designs or long-term production requirements, selection of active substitute parts (AO7412 or SI1404BDH-T1-GE3) is recommended to ensure supply chain continuity.