IXFK55N50 Equivalent & Substitute Parts

Part Overview

The IXFK55N50 is an N-Channel 500V 55A MOSFET manufactured by IXYS in the HiPerFET™ series, housed in a TO-264AA through-hole package. This device is classified as obsolete, indicating discontinued production and limited availability for new designs. The part delivers 625W maximum power dissipation and operates across the industrial temperature range of -55°C to 150°C.

Due to its obsolete status, equivalent and substitute parts are necessary for ongoing production support, design continuity, and component sourcing. Substitute devices must maintain electrical compatibility within the 500V drain-source voltage class while accommodating the specified current and thermal requirements of the application.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	55	A
Rds On (Max) @ 27.5A, 10V	90	mOhm
Gate Threshold Voltage (Vgs(th)) @ 8mA	4.5	V
Gate Charge (Qg) @ 10V	330	nC
Input Capacitance (Ciss) @ 25V	9400	pF
Power Dissipation (Max)	625	W
Operating Temperature Range	-55 to 150	°C
Package Type	TO-264AA	Through Hole
Product Status	Obsolete	—

Substitute Part Grouping Explanation

Substitution of the IXFK55N50 is determined by the following critical electrical and mechanical parameters:

Primary Compatibility Criteria:

Drain to Source Voltage (Vdss): 500V minimum
Continuous Drain Current (Id): Equal to or greater than 55A
Gate Drive Voltage: 10V nominal
Operating Temperature Range: -55°C to 150°C minimum
Mounting Type: Through Hole
Package Compatibility: TO-264AA or TO-264-3 variants

Substitution Logic:

Substitute parts are grouped into two categories based on electrical performance and package form factor:

Category 1: Direct Electrical Upgrade (Same Voltage Class, Higher Current Rating) The IXFK94N50P2 operates at identical 500V Vdss with significantly higher current capacity (94A vs. 55A) and improved thermal performance (1300W vs. 625W). This part maintains the same TO-264AA package and IXYS manufacturer lineage, providing direct functional replacement with enhanced capability margins.

Category 2: Equivalent Performance (500V Class, Similar Current Range) The APT56M50L (Microchip, 56A, 780W) and STY60NM50 (STMicroelectronics, 60A, 560W) deliver comparable current ratings within 2-9% of the original specification. Both maintain 500V Vdss and through-hole mounting, with package variants (TO-264 and MAX247™) that accommodate standard PCB layouts.

Category 3: Higher Voltage Alternative (650V Class) The SPW47N60C3FKSA1 (Infineon, 650V, 47A) operates at elevated voltage with reduced current capacity. This part is suitable only for applications where higher voltage margin is required and current demand does not exceed 47A. Package form factor differs (TO-247-3 vs. TO-264AA).

Category 4: Lower Current Alternative (500V Class, Reduced Rating) The FQL40N50F (onsemi, 40A, 460W) provides 500V operation at reduced current capacity. This part is applicable only when application current requirements do not exceed 40A.

Parameter Comparison

Parameter	IXFK55N50	IXFK94N50P2	APT56M50L	STY60NM50	SPW47N60C3FKSA1	FQL40N50F
Manufacturer	IXYS	IXYS	Microchip	STMicroelectronics	Infineon	onsemi
Vdss (V)	500	500	500	500	650	500
Id @ 25°C (A)	55	94	56	60	47	40
Rds On (Max) (mOhm)	90 @ 27.5A	55 @ 500mA	100 @ 28A	50 @ 30A	70 @ 30A	110 @ 20A
Vgs(th) (Max) (V)	4.5	5.0	5.0	5.0	3.9	5.0
Gate Charge Qg @ 10V (nC)	330	220	220	266	320	200
Ciss @ 25V (pF)	9400	13700	8800	7500	6800	7500
Power Dissipation (Max) (W)	625	1300	780	560	415	460
Operating Temperature (°C)	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150
Package	TO-264AA	TO-264AA	TO-264	MAX247™	TO-247-3	TO-264-3
Product Status	Obsolete	Active	Active	Active	Active	Obsolete
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: IXFK94N50P2

The IXFK94N50P2 is the preferred substitute for the IXFK55N50. This part maintains identical electrical specifications (500V Vdss, 10V gate drive) while providing 71% higher current capacity (94A vs. 55A) and 108% higher power dissipation rating (1300W vs. 625W). The device is housed in the same TO-264AA package, ensuring direct PCB compatibility without layout modification. The IXFK94N50P2 carries Active product status with ROHS3 compliance and unlimited moisture sensitivity rating (MSL 1), supporting long-term production availability and supply chain stability.

Secondary Recommendation: APT56M50L

The APT56M50L (Microchip Technology) provides equivalent performance with 56A continuous current and 780W power dissipation, representing a 2% increase over the original specification. This part maintains 500V Vdss and 10V gate drive compatibility. The TO-264 package accommodates standard through-hole PCB layouts. Active product status and ROHS3 compliance ensure ongoing availability. This option is suitable when IXYS-specific sourcing is constrained.

Tertiary Recommendation: STY60NM50

The STY60NM50 (STMicroelectronics) delivers 60A continuous current and 560W power dissipation at 500V Vdss. This part offers improved on-resistance (50 mOhm vs. 90 mOhm) and reduced gate charge (266 nC vs. 330 nC), resulting in lower switching losses. The MAX247™ package requires PCB layout verification for pin compatibility. Active product status and ROHS3 compliance support production continuity.

Not Recommended for Direct Substitution:

The SPW47N60C3FKSA1 operates at 650V Vdss with reduced current capacity (47A). This part introduces higher voltage stress on circuit components and is suitable only for applications with explicit 650V voltage margin requirements and current demand below 47A. Package form factor (TO-247-3) differs from the original TO-264AA.

The FQL40N50F is obsolete and provides reduced current capacity (40A vs. 55A), limiting its application scope. This part is not recommended for new designs or production support.

Frequently Asked Questions (FAQ)

Q1: Can the IXFK94N50P2 directly replace the IXFK55N50 without PCB modification?

Yes. The IXFK94N50P2 is housed in the identical TO-264AA package with matching pin configuration and spacing. No PCB layout changes are required. The higher current and power ratings provide additional performance margin without introducing compatibility issues.

Q2: What is the primary reason the IXFK55N50 requires substitution?

The IXFK55N50 is classified as obsolete, indicating discontinued production by IXYS. Obsolete status creates supply chain risk and limits availability for ongoing production support. Active substitute parts ensure long-term component sourcing and design continuity.

Q3: Are all substitute parts rated for the same operating temperature range?

Yes. All substitute parts listed operate across the -55°C to 150°C temperature range, matching the original IXFK55N50 specification. This ensures thermal compatibility in industrial and automotive applications.

Q4: How does the IXFK94N50P2 differ electrically from the IXFK55N50?

The IXFK94N50P2 maintains identical 500V Vdss and 10V gate drive voltage. Key differences include higher continuous current (94A vs. 55A), improved on-resistance (55 mOhm vs. 90 mOhm), reduced gate charge (220 nC vs. 330 nC), and higher power dissipation rating (1300W vs. 625W). These improvements result in lower switching losses and enhanced thermal performance.

Q5: Can the SPW47N60C3FKSA1 be used as a direct substitute?

The SPW47N60C3FKSA1 is not a direct substitute. This part operates at 650V Vdss (vs. 500V) and provides reduced current capacity (47A vs. 55A). The TO-247-3 package differs from the original TO-264AA, requiring PCB layout modification. This part is suitable only for applications requiring higher voltage margin and operating below 47A continuous current.

Q6: What compliance certifications apply to all substitute parts?

All substitute parts listed are ROHS3 compliant and REACH unaffected, matching the original IXFK55N50 certifications. These designations ensure environmental compliance and regulatory acceptance in industrial and consumer applications.

Q7: How do package differences affect substitution decisions?

Package form factor determines PCB compatibility and thermal performance. The IXFK94N50P2 and APT56M50L maintain through-hole TO-264 variants compatible with standard PCB layouts. The STY60NM50 uses MAX247™ packaging, requiring pin-to-pin verification. The SPW47N60C3FKSA1 employs TO-247-3 packaging, necessitating PCB redesign. Package selection depends on existing PCB layout constraints and thermal management requirements.

Q8: Which substitute part offers the lowest on-resistance?

The STY60NM50 provides the lowest on-resistance at 50 mOhm (measured at 30A, 10V gate drive), compared to 90 mOhm for the original IXFK55N50. Lower on-resistance reduces conduction losses and heat generation, improving overall circuit efficiency.

Q9: Are all substitute parts available in active production status?

Four of five substitute parts carry Active product status: IXFK94N50P2, APT56M50L, STY60NM50, and SPW47N60C3FKSA1. The FQL40N50F is obsolete and not recommended for new designs. Active status ensures ongoing manufacturing, supply chain availability, and long-term design support.

Q10: What is the inventory status of substitute parts?

The IXFK94N50P2 has the highest inventory availability (43,400 pcs), followed by SPW47N60C3FKSA1 (480,100 pcs). The APT56M50L (1,812 pcs) and STY60NM50 (1,219 pcs) have limited stock. Inventory levels are subject to change and should be verified with component suppliers for production planning.

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