IXFK73N30 Equivalent & Substitute Parts

Part Overview

The IXFK73N30 is an N-Channel MOSFET rated for 300V drain-to-source voltage with 73A continuous drain current at 25°C. Manufactured by IXYS under the HiPerFET™ series, this device is packaged in TO-264AA through-hole configuration and rated for 500W maximum power dissipation. The part is designated as Last Time Buy, indicating discontinued production status. Identification of equivalent and substitute parts is necessary to support ongoing system maintenance, design updates, and procurement continuity.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	300	V
Continuous Drain Current (Id) @ 25°C	73	A
On-State Resistance (Rds On Max) @ 10V	45	mOhm
Gate Threshold Voltage (Vgs th Max)	4	V
Gate Charge (Qg Max) @ 10V	360	nC
Input Capacitance (Ciss Max) @ 25V	9000	pF
Power Dissipation (Max)	500	W
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole
Package	TO-264AA

Substitute Part Grouping Explanation

Substitution of the IXFK73N30 is determined by the following critical parameters:

Voltage Rating Compatibility: The drain-to-source voltage (Vdss) must equal or exceed 300V to maintain circuit protection margins.

Current Capacity: The continuous drain current (Id) must meet or exceed 73A at 25°C to support the same load conditions.

On-State Resistance: The Rds On value directly affects power dissipation and thermal performance. Lower Rds On values indicate improved efficiency.

Gate Charge and Input Capacitance: These parameters affect switching speed and gate drive requirements. Significant deviations may require circuit redesign.

Package Compatibility: The TO-264AA through-hole package is the primary mechanical constraint.

Operating Temperature Range: The -55°C to 150°C range must be maintained or exceeded.

Based on these criteria, substitute parts are grouped as follows:

Group 1 (Direct Upgrade): IXFK88N30P—same voltage rating (300V), higher current capacity (88A), improved Rds On (40mOhm), same package (TO-264AA), same manufacturer series (HiPerFET™), Active product status.

Group 2 (Voltage Derating Required): FQL40N50F—higher voltage rating (500V), lower current capacity (40A), higher Rds On (110mOhm), compatible package (TO-264-3), different manufacturer (onsemi), Obsolete product status.

Parameter Comparison

Parameter	IXFK73N30	IXFK88N30P	FQL40N50F	Unit
Manufacturer	IXYS	IXYS	onsemi
FET Type	N-Channel	N-Channel	N-Channel
Technology	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)	MOSFET (Metal Oxide)
Drain-to-Source Voltage (Vdss)	300	300	500	V
Continuous Drain Current (Id) @ 25°C	73	88	40	A
Rds On (Max) @ 10V	45	40	110	mOhm
Gate Threshold Voltage (Vgs th Max)	4	5	5	V
Gate Charge (Qg Max) @ 10V	360	180	200	nC
Input Capacitance (Ciss Max) @ 25V	9000	6300	7500	pF
Power Dissipation (Max)	500	600	460	W
Operating Temperature Range	-55 to 150	-55 to 150	-55 to 150	°C
Mounting Type	Through Hole	Through Hole	Through Hole
Package	TO-264AA	TO-264AA	TO-264-3
Product Status	Last Time Buy	Active	Obsolete
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected

Engineering Selection Recommendations

IXFK88N30P (Recommended Primary Substitute)

The IXFK88N30P is the preferred substitute for the IXFK73N30. Both devices share identical voltage ratings (300V), the same manufacturer (IXYS), the same product series (HiPerFET™), and compatible through-hole packaging (TO-264AA). The IXFK88N30P provides higher continuous drain current (88A versus 73A), improved on-state resistance (40mOhm versus 45mOhm), and higher power dissipation capability (600W versus 500W). The IXFK88N30P maintains Active product status, ensuring long-term availability and supply chain stability. Gate charge is reduced (180nC versus 360nC), and input capacitance is lower (6300pF versus 9000pF), resulting in faster switching characteristics. All regulatory compliance requirements (ROHS3, REACH Unaffected) are met. This part is a direct functional upgrade with no circuit redesign required.

FQL40N50F (Limited Substitution)

The FQL40N50F is an alternative substitute only in applications where voltage derating is acceptable. This device operates at 500V drain-to-source voltage, providing higher voltage margin than the original 300V specification. However, the continuous drain current is significantly reduced (40A versus 73A), and on-state resistance is substantially higher (110mOhm versus 45mOhm), resulting in increased power dissipation and thermal stress. The FQL40N50F is designated Obsolete, creating long-term supply and support risks. The TO-264-3 package is mechanically compatible with TO-264AA footprints. This substitute is suitable only for applications with reduced current requirements or where higher voltage rating provides system-level benefits. All regulatory compliance requirements (ROHS3, REACH Unaffected) are met.

Frequently Asked Questions (FAQ)

Q: Can the IXFK88N30P directly replace the IXFK73N30 without circuit modifications?

A: Yes. The IXFK88N30P is a direct replacement. Both devices share the same 300V voltage rating, identical TO-264AA package, and compatible gate drive characteristics. The IXFK88N30P provides superior performance with higher current capacity and lower on-state resistance.

Q: What are the key differences between the IXFK73N30 and IXFK88N30P?

A: The IXFK88N30P offers higher continuous drain current (88A versus 73A), lower on-state resistance (40mOhm versus 45mOhm), higher power dissipation rating (600W versus 500W), lower gate charge (180nC versus 360nC), and lower input capacitance (6300pF versus 9000pF). Both maintain the same 300V voltage rating and operating temperature range.

Q: Is the FQL40N50F suitable as a direct replacement?

A: The FQL40N50F is not a direct replacement. While the TO-264-3 package is mechanically compatible, the device has significantly lower current capacity (40A versus 73A) and higher on-state resistance (110mOhm versus 45mOhm). The higher voltage rating (500V) is not required for 300V applications. This substitute is appropriate only for applications with reduced current demands.

Q: Why is the IXFK73N30 designated as Last Time Buy?

A: Last Time Buy status indicates that IXYS has discontinued production of this device. The IXFK88N30P is the recommended replacement, offering improved specifications and Active product status for continued availability.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. The IXFK73N30, IXFK88N30P, and FQL40N50F are all ROHS3 Compliant and REACH Unaffected, meeting current environmental and regulatory requirements.

Q: What is the impact of lower gate charge in the IXFK88N30P?

A: Lower gate charge (180nC versus 360nC) reduces gate drive power requirements and enables faster switching transitions. This improves overall circuit efficiency and may reduce thermal stress on gate drive circuitry.

Q: Can the FQL40N50F be used in a 300V application?

A: Yes, the FQL40N50F can operate in a 300V application due to its 500V rating. However, the significantly reduced current capacity (40A versus 73A) and higher on-state resistance (110mOhm versus 45mOhm) make it unsuitable for applications requiring the full 73A current specification of the original device.

Q: What is the difference between TO-264AA and TO-264-3 packages?

A: Both are through-hole packages with compatible pin configurations and footprints. TO-264AA and TO-264-3 designations refer to the same physical package form factor used for power MOSFETs. Mechanical substitution is feasible between these package types.

Q: Which substitute part should be selected for new designs?

A: The IXFK88N30P is the recommended choice for new designs. It provides superior electrical performance, Active product status ensuring long-term availability, and identical voltage and package specifications to the original IXFK73N30.

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