IXFK35N50 N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IXFK35N50 is an N-Channel MOSFET manufactured by IXYS, rated for 500V drain-to-source voltage with 35A continuous drain current at 25°C. This device is packaged in a Through Hole TO-264AA configuration and is part of the HiPerFET™ series. The IXFK35N50 is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support, maintenance, and production continuity. Substitute parts must maintain electrical compatibility within the 500V voltage class while accommodating the thermal and current requirements of the application.

Substiute Parts

IXFK35N50

IXYSIn Stock: 767IXFK35N50 Datasheet

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IXFK44N80P

IXYSIn Stock: 1414IXFK44N80P Datasheet

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FQL40N50F

onsemiIn Stock: 18775FQL40N50F Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the IXFK35N50 is determined by the following critical parameters:

Voltage Class Compatibility: The primary substitution criterion is maintenance of the 500V Vdss rating. Substitute parts must operate at or above 500V to ensure safe operation in circuits designed for this voltage class.

Current Rating: Substitute parts must provide continuous drain current (Id) equal to or greater than 35A at 25°C to support the load requirements of the original design.

On-State Resistance (Rds On): The on-state resistance directly affects power dissipation and thermal performance. Substitute parts with lower Rds On values improve efficiency and reduce heat generation.

Gate Charge (Qg): Gate charge affects switching speed and driver circuit requirements. Substitute parts with comparable or lower gate charge maintain switching characteristics.

Thermal Performance: Power dissipation capability must meet or exceed the original 416W specification to ensure adequate thermal management.

Package Compatibility: The TO-264AA Through Hole package is the primary mounting requirement. Substitute parts must use compatible package footprints.

Two substitute parts are identified: the FQL40N50F (onsemi) and the IXFK44N80P (IXYS). The FQL40N50F maintains the 500V voltage class with improved current rating and lower on-state resistance. The IXFK44N80P operates at a higher 800V voltage class and is suitable only for applications where voltage derating is acceptable.

Parameter Comparison

Engineering Selection Recommendations

FQL40N50F (onsemi): This substitute maintains the 500V voltage class and provides superior electrical characteristics compared to the IXFK35N50. The FQL40N50F delivers 40A continuous drain current, exceeding the original 35A specification. The on-state resistance is reduced to 110 mOhm, resulting in lower power dissipation and improved thermal efficiency. Gate charge is reduced to 200 nC, enabling faster switching response. Power dissipation capability is rated at 460W, meeting the thermal requirements of the original design. The FQL40N50F is RoHS3 compliant and REACH unaffected. Although classified as obsolete, this part maintains full electrical compatibility and is suitable for direct substitution in applications requiring 500V operation.

IXFK44N80P (IXYS): This substitute operates at 800V, representing a higher voltage class than the original IXFK35N50. The IXFK44N80P is classified as active and is RoHS3 compliant. This part is suitable only for applications where the circuit design permits voltage derating or where higher voltage capability is beneficial. The 44A continuous drain current and 1040W power dissipation capability exceed the original specifications. The on-state resistance is 190 mOhm, higher than the IXFK35N50, resulting in increased power dissipation at equivalent current levels. Gate charge is comparable at 198 nC. The IXFK44N80P is packaged in TO-264AA, maintaining mechanical compatibility.

For direct replacement in existing 500V designs, the FQL40N50F is the preferred substitute. The IXFK44N80P is suitable only when circuit topology permits higher voltage operation.

Frequently Asked Questions (FAQ)

Q: Can the FQL40N50F directly replace the IXFK35N50 in a 500V application?

A: Yes. The FQL40N50F maintains the 500V Vdss rating and provides superior electrical performance with 40A continuous drain current, lower on-state resistance (110 mOhm), and reduced gate charge (200 nC). The TO-264-3 package is mechanically compatible with TO-264AA footprints. Direct substitution is supported.

Q: Is the IXFK44N80P suitable as a direct replacement for the IXFK35N50?

A: The IXFK44N80P is not a direct replacement due to its 800V voltage rating. This part is suitable only for applications where the circuit design permits voltage derating or where higher voltage capability is required. The higher on-state resistance (190 mOhm) results in increased power dissipation compared to the original part.

Q: What is the significance of the on-state resistance (Rds On) difference between these parts?

A: On-state resistance directly determines power dissipation during conduction. The FQL40N50F (110 mOhm) dissipates less power than the IXFK35N50 (150 mOhm) at equivalent current levels, improving thermal performance and efficiency. The IXFK44N80P (190 mOhm) dissipates more power, requiring enhanced thermal management.

Q: Are there package compatibility concerns between TO-264AA and TO-264-3?

A: Both TO-264AA and TO-264-3 are Through Hole packages with compatible pin configurations and footprints. Mechanical substitution is supported without PCB redesign.

Q: What is the product status significance for these substitute parts?

A: The IXFK35N50 and FQL40N50F are both classified as obsolete, indicating discontinued production. The IXFK44N80P is active and currently manufactured. For long-term supply assurance, the IXFK44N80P is preferred if voltage derating is acceptable. Current inventory levels should be verified with suppliers.

Q: How do gate charge differences affect circuit performance?

A: Gate charge (Qg) determines the energy required to switch the MOSFET and influences switching speed. The FQL40N50F (200 nC) and IXFK44N80P (198 nC) have lower gate charge than the IXFK35N50 (227 nC), enabling faster switching response and potentially reducing driver circuit stress.

Q: Are compliance certifications equivalent across these parts?

A: The FQL40N50F is RoHS3 compliant and REACH unaffected. The IXFK44N80P is RoHS3 compliant and REACH unaffected. Both parts meet current regulatory requirements. The IXFK35N50 compliance status is not specified in available documentation.