FDB8443 N-Channel MOSFET 40V 25A/120A TO-263 Equivalent & Substitute Parts

Part Overview

The FDB8443 is an N-Channel MOSFET manufactured by onsemi, rated for 40V drain-to-source voltage with continuous drain current of 25A at Ta (ambient temperature) and 120A at Tc (case temperature). The device is housed in a TO-263 (D2PAK) surface mount package and is part of the PowerTrench® series. The FDB8443 is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support, production continuity, and system maintenance. Active alternative devices with compatible electrical and mechanical specifications are available from multiple manufacturers.

Substiute Parts

FDB8443

onsemiIn Stock: 5152FDB8443 Datasheet

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BUK765R2-40B,118

NXP USA Inc.In Stock: 24087BUK765R2-40B,118 Datasheet

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BUK9609-40B,118

Nexperia USA Inc.In Stock: 6360BUK9609-40B,118 Datasheet

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IRF1404ZSTRLPBF

Infineon TechnologiesIn Stock: 22267IRF1404ZSTRLPBF Datasheet

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IXTA220N04T2

IXYSIn Stock: 1524IXTA220N04T2 Datasheet

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STB100NF04T4

STMicroelectronicsIn Stock: 15280STB100NF04T4 Datasheet

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STB120N4F6

STMicroelectronicsIn Stock: 15166STB120N4F6 Datasheet

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STB120N4LF6

STMicroelectronicsIn Stock: 15511STB120N4LF6 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the FDB8443 is determined by strict alignment of electrical and mechanical parameters. The following criteria establish substitution validity:

Primary Matching Criteria:

• Drain-to-Source Voltage (Vdss): Must equal 40V
• Package Type: Must be TO-263-3 (D2PAK) or equivalent surface mount D2PAK
• FET Type: Must be N-Channel
• Technology: Must be MOSFET (Metal Oxide)
• Operating Temperature Range: Must span -55°C to 175°C minimum

Secondary Compatibility Criteria:

• Continuous Drain Current (Tc): Substitute must meet or exceed 120A at case temperature
• On-State Resistance (Rds On): Lower or equal values indicate improved performance
• Gate Charge (Qg): Lower values reduce gate drive requirements
• Input Capacitance (Ciss): Lower values reduce switching losses
• Power Dissipation: Higher ratings provide thermal margin

All substitute parts listed meet the primary matching criteria. Differences in secondary parameters reflect design variations across manufacturers while maintaining functional compatibility within the FDB8443 application envelope.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Highest Compatibility):

STB100NF04T4 (STMicroelectronics) and STB120N4LF6 (STMicroelectronics) are the most direct substitutes. Both devices match the FDB8443 in Vdss (40V), package type (D2PAK), and operating temperature range. STB100NF04T4 provides 120A continuous drain current at Tc, matching the FDB8443 specification exactly. STB120N4LF6 provides 80A at Tc with lower gate charge (80 nC vs. 185 nC), reducing gate drive power. Both are AEC-Q101 qualified automotive-grade devices with active product status and ROHS3 compliance.

Secondary Substitutes (Extended Current Capability):

IRF1404ZSTRLPBF (Infineon) provides 180A continuous drain current at Tc, exceeding FDB8443 capability. This device is suitable for applications requiring higher current headroom. On-state resistance is 3.7 mOhm at 75A, comparable to the FDB8443. Gate charge is 150 nC, lower than the FDB8443, reducing switching losses. Product status is active with ROHS3 compliance.

Alternative Substitutes (Lower Current Rating):

BUK765R2-40B,118 (NXP) and BUK9609-40B,118 (Nexperia) provide 75A continuous drain current at Tc, below the FDB8443 rating. These devices are suitable only for applications where 75A continuous current is sufficient. Both are AEC-Q101 qualified automotive-grade devices with active product status. BUK9609-40B features lower gate charge (32 nC) and lower threshold voltage (2V), improving switching performance.

Selection Basis:

All substitute parts are classified as active products, ensuring long-term availability and manufacturing support. STMicroelectronics devices carry AEC-Q101 automotive qualification, appropriate for mission-critical applications. All listed substitutes maintain ROHS3 compliance and REACH unaffected status, matching the FDB8443 regulatory profile. Package compatibility (TO-263-3 D2PAK) is maintained across all substitutes, enabling direct PCB footprint replacement.

Frequently Asked Questions (FAQ)

Q: Can STB120N4LF6 replace FDB8443 in all applications?

A: STB120N4LF6 provides 80A continuous drain current at Tc, below the FDB8443 specification of 120A at Tc. Substitution is valid only for applications where 80A continuous current is sufficient. Verify application current requirements before selection.

Q: What is the difference between STB100NF04T4 and STB120N4LF6?

A: STB100NF04T4 provides 120A continuous drain current at Tc, matching the FDB8443. STB120N4LF6 provides 80A at Tc. STB120N4LF6 features lower gate charge (80 nC vs. 150 nC), reducing gate drive power. STB100NF04T4 is the direct current-matched substitute.

Q: Are all substitute parts automotive qualified?

A: BUK765R2-40B,118, BUK9609-40B,118, STB100NF04T4, and STB120N4LF6 carry AEC-Q101 automotive qualification. IRF1404ZSTRLPBF does not list automotive qualification in the provided specifications.

Q: Can IRF1404ZSTRLPBF be used as a direct replacement?

A: IRF1404ZSTRLPBF is electrically compatible with FDB8443 (40V Vdss, D2PAK package, -55°C to 175°C operating range). The device provides 180A continuous drain current at Tc, exceeding FDB8443 capability. On-state resistance (3.7 mOhm) is comparable. Substitution is valid for applications where higher current capability is acceptable.

Q: What is the significance of gate charge (Qg) differences?

A: Gate charge determines the energy required to switch the MOSFET. Lower gate charge reduces gate drive power dissipation and switching losses. FDB8443 has 185 nC gate charge. BUK9609-40B,118 has 32 nC, significantly lower. Applications with power-limited gate drivers benefit from lower gate charge devices.

Q: Are all substitutes available in the same packaging?

A: All substitute parts use TO-263-3 (D2PAK) or equivalent surface mount D2PAK packaging. IRF1404ZSTRLPBF uses PG-TO263-3 designation, which is functionally equivalent to D2PAK. PCB footprint compatibility is maintained across all substitutes.

Q: What is the impact of on-state resistance (Rds On) variation?

A: Lower Rds On reduces conduction losses and heat dissipation. FDB8443 has 3 mOhm at 80A, 10V. IRF1404ZSTRLPBF has 3.7 mOhm at 75A, 10V. STB100NF04T4 has 4.6 mOhm at 50A, 10V. Applications with high continuous current benefit from lower Rds On values.

Q: Can BUK765R2-40B,118 or BUK9609-40B,118 be used if application current is below 75A?

A: Yes. Both devices are rated for 75A continuous drain current at Tc. Applications requiring less than 75A continuous current can use these devices. Verify that application current does not exceed 75A at case temperature.

Q: What compliance certifications are maintained across substitutes?

A: All substitute parts maintain ROHS3 compliance and REACH unaffected status, matching FDB8443 regulatory requirements. Moisture sensitivity level (MSL) is 1 (Unlimited) for all devices, indicating no moisture sensitivity precautions are required.

Q: Is thermal performance affected by substitute selection?

A: Power dissipation ratings vary: FDB8443 (188W), STB100NF04T4 (300W), IRF1404ZSTRLPBF (200W), STB120N4LF6 (110W). Higher power dissipation ratings provide greater thermal margin. Application thermal design should account for the selected device's power dissipation capability.