IXFK33N50 N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The IXFK33N50 is an N-Channel MOSFET manufactured by IXYS, rated for 500V drain-to-source voltage with 33A continuous drain current at 25°C. This device is part of the HiPerFET™ series and is housed in a TO-264AA through-hole package. The part is currently classified as obsolete, making identification of equivalent and substitute components essential for ongoing design support, production continuity, and system maintenance.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	33	A
On-State Resistance (Rds On Max) @ 16.5A, 10V	160	mOhm
Gate Threshold Voltage (Vgs(th) Max) @ 4mA	4	V
Gate Charge (Qg Max) @ 10V	227	nC
Power Dissipation (Max)	416	W
Operating Temperature Range	-55 to 150	°C
Package Type	TO-264AA	Through Hole

Substitute Part Grouping Explanation

Substitution of the IXFK33N50 is determined by the following critical electrical and mechanical parameters:

Voltage Rating (Vdss): The substitute must equal or exceed 500V to maintain system voltage margin and reliability.

Current Rating (Id): The substitute must equal or exceed 33A continuous drain current to support the same load conditions.

On-State Resistance (Rds On): Lower Rds On values reduce conduction losses and heat dissipation, making higher-performance substitutes acceptable.

Package Type: The substitute must be compatible with TO-264AA or TO-264-3 through-hole mounting to ensure mechanical fit and thermal interface compatibility.

Operating Temperature Range: The substitute must support the full -55°C to 150°C operating range.

Two substitute parts meet these criteria:

IXFK36N60P (Direct Manufacturer Substitute): Higher voltage rating (600V) and higher current rating (36A) with improved specifications, same manufacturer series, active product status.
FQL40N50F (Similar Manufacturer Substitute): Matched voltage rating (500V), higher current rating (40A), compatible package, different manufacturer (onsemi).

Parameter Comparison

Parameter	IXFK33N50	IXFK36N60P	FQL40N50F	Unit
Manufacturer	IXYS	IXYS	onsemi	—
Drain-to-Source Voltage (Vdss)	500	600	500	V
Continuous Drain Current (Id) @ 25°C	33	36	40	A
Rds On (Max) @ Vgs 10V	160 @ 16.5A	190 @ 18A	110 @ 20A	mOhm
Gate Threshold Voltage (Vgs(th) Max)	4 @ 4mA	5 @ 4mA	5 @ 250µA	V
Gate Charge (Qg Max) @ 10V	227	102	200	nC
Input Capacitance (Ciss Max) @ 25V	5700	5800	7500	pF
Power Dissipation (Max)	416	650	460	W
Operating Temperature Range	-55 to 150	-55 to 150	-55 to 150	°C
Package Type	TO-264AA	TO-264AA	TO-264-3	—
Product Status	Obsolete	Active	Obsolete	—
RoHS Status	Not specified	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

IXFK36N60P Selection Criteria:

The IXFK36N60P is the preferred direct substitute from the original manufacturer IXYS. This part maintains the HiPerFET™ series lineage and is classified as an active product, ensuring long-term availability and supply chain stability. The higher voltage rating (600V vs. 500V) provides additional system margin without compromising application compatibility. The increased current rating (36A vs. 33A) and power dissipation capability (650W vs. 416W) support higher-performance implementations. This part is ROHS3 compliant and REACH unaffected, meeting modern regulatory requirements. The TO-264AA package maintains identical mechanical compatibility with the original design.

FQL40N50F Selection Criteria:

The FQL40N50F from onsemi provides an alternative solution with matched voltage rating (500V) and superior current handling (40A vs. 33A). The lower on-state resistance (110mOhm vs. 160mOhm) reduces conduction losses. However, this part is classified as obsolete, limiting its suitability for new long-term designs. The TO-264-3 package is mechanically compatible with TO-264AA mounting. This part is ROHS3 compliant and REACH unaffected. Selection of this substitute is appropriate only when existing inventory or legacy system requirements mandate its use.

Frequently Asked Questions (FAQ)

Q: Can the IXFK36N60P directly replace the IXFK33N50 in existing designs?

A: Yes. The IXFK36N60P meets or exceeds all critical electrical parameters of the IXFK33N50. The higher voltage rating (600V) and current rating (36A) ensure compatibility with applications designed for the original part. The TO-264AA package provides identical mechanical fit. No circuit modifications are required.

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

A: Both packages are through-hole mounted variants of the TO-264 family with identical pin configurations and thermal interface characteristics. TO-264AA and TO-264-3 are mechanically interchangeable in standard PCB layouts. Thermal performance and mounting procedures remain consistent between these package designations.

Q: Why is the IXFK36N60P rated for higher voltage and current than the IXFK33N50?

A: The IXFK36N60P represents an improved generation within the HiPerFET™ series. Enhanced semiconductor design and manufacturing processes enable higher voltage blocking capability (600V vs. 500V) and increased current handling (36A vs. 36A) while maintaining the same package form factor. These improvements do not affect backward compatibility with lower-rated applications.

Q: Is the FQL40N50F suitable for new production designs?

A: The FQL40N50F is classified as obsolete and is not recommended for new production designs. While it provides superior electrical performance (40A current, 110mOhm Rds On), its discontinued status creates long-term supply chain risk. The IXFK36N60P is the recommended choice for new designs due to its active product status and manufacturer support.

Q: What are the compliance and regulatory differences between these parts?

A: The IXFK36N60P is ROHS3 compliant and REACH unaffected, meeting current regulatory requirements for electronic components. The FQL40N50F is also ROHS3 compliant and REACH unaffected. The original IXFK33N50 compliance status is not specified in available documentation. For applications requiring documented regulatory compliance, the IXFK36N60P is the appropriate selection.

Q: How do gate charge differences affect circuit design?

A: The IXFK36N60P exhibits lower gate charge (102nC vs. 227nC), requiring less energy to switch the device. This reduces gate driver power consumption and enables faster switching transitions. The FQL40N50F gate charge (200nC) is comparable to the original part. Gate charge differences do not prevent substitution but may improve overall circuit efficiency when using the IXFK36N60P.

Q: Are there thermal performance considerations when substituting these parts?

A: The IXFK36N60P has higher power dissipation capability (650W vs. 416W) and lower on-state resistance, potentially reducing junction temperature in high-current applications. The FQL40N50F offers the lowest on-state resistance (110mOhm), providing superior thermal performance. Both substitutes are compatible with existing thermal management solutions designed for the IXFK33N50. Thermal interface materials and mounting procedures remain unchanged.

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