IXFK66N50Q2 Equivalent & Substitute Parts

Part Overview

The IXFK66N50Q2 is an N-Channel MOSFET rated for 500V drain-to-source voltage with 66A continuous drain current at 25°C, housed in a TO-264AA through-hole package. Manufactured by IXYS under the HiPerFET™ series, this device is classified as obsolete. Due to its obsolete status, equivalent and substitute parts from active product lines are necessary to maintain design continuity and ensure long-term component availability for new designs and production requirements.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	66	A
On-State Resistance (Rds On Max) @ 10V	80	mOhm
Gate Threshold Voltage (Vgs(th) Max)	4.5	V @ 8mA
Power Dissipation (Max)	735	W
Operating Temperature Range	-55 to 150	°C
Package Type	TO-264AA	Through Hole
Gate Charge (Qg Max) @ 10V	200	nC
Input Capacitance (Ciss Max) @ 25V	8400	pF

Substitute Part Grouping Explanation

Substitution eligibility for the IXFK66N50Q2 is determined by the following critical parameters:

Voltage Rating: All substitute parts must maintain the 500V Vdss specification to ensure safe operation in the same circuit topology.

Current Rating: Substitute parts must support a continuous drain current equal to or greater than 66A at 25°C to handle the design load without thermal stress.

On-State Resistance: Rds On values must be equal to or lower than 80 mOhm at the specified gate voltage to maintain or improve power efficiency and thermal performance.

Package Compatibility: Substitute parts must use through-hole mounting packages compatible with TO-264AA footprints or equivalent mechanical dimensions.

Operating Temperature: All substitutes must support the -55°C to 150°C temperature range.

Compliance: All substitute parts must maintain RoHS3 compliance and REACH unaffected status.

The following parts meet these substitution criteria:

IXFK80N50Q3 (IXYS): Active product with 80A rating, improved Rds On of 65 mOhm, same voltage class, same package family, and higher power dissipation capability.

APT75F50B2 (Microchip Technology): Active product with 75A rating, 75 mOhm Rds On, same voltage class, compatible through-hole package (T-MAX™ [B2]), and higher power dissipation capability.

Parameter Comparison

Parameter	IXFK66N50Q2	IXFK80N50Q3	APT75F50B2	Unit
Manufacturer	IXYS	IXYS	Microchip Technology	—
Product Status	Obsolete	Active	Active	—
Drain-to-Source Voltage (Vdss)	500	500	500	V
Continuous Drain Current (Id) @ 25°C	66	80	75	A
On-State Resistance (Rds On Max) @ 10V	80	65	75	mOhm
Gate Threshold Voltage (Vgs(th) Max)	4.5	6.5	5	V @ specified Id
Power Dissipation (Max)	735	1250	1040	W
Operating Temperature Range	-55 to 150	-55 to 150	-55 to 150	°C
Gate Charge (Qg Max) @ 10V	200	200	290	nC
Input Capacitance (Ciss Max) @ 25V	8400	10000	11600	pF
Mounting Type	Through Hole	Through Hole	Through Hole	—
Package	TO-264AA	TO-264AA	T-MAX™ [B2]	—
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—
REACH Status	REACH Unaffected	REACH Unaffected	REACH Unaffected	—

Engineering Selection Recommendations

IXFK80N50Q3 is the primary substitute for direct replacement applications. This part is manufactured by IXYS, the original manufacturer of the IXFK66N50Q2, ensuring design continuity within the HiPerFET™ product family. The IXFK80N50Q3 is classified as active, guaranteeing long-term availability. It provides superior electrical performance with 80A continuous current capability and reduced on-state resistance of 65 mOhm compared to the original 80 mOhm specification. The identical TO-264AA package ensures mechanical and thermal compatibility without PCB redesign. Higher power dissipation capability (1250W vs. 735W) provides additional thermal margin. All compliance certifications (RoHS3, REACH unaffected) are maintained.

APT75F50B2 serves as an alternative substitute when IXYS parts are unavailable or when design flexibility permits package variation. Manufactured by Microchip Technology, this part is active and widely available. It delivers 75A continuous current with 75 mOhm on-state resistance, both exceeding the original specification. The T-MAX™ [B2] package is a through-hole variant compatible with TO-264-3 footprints, though PCB layout verification is required due to package geometry differences. Power dissipation capability of 1040W exceeds the original device. All compliance requirements are satisfied.

Both substitutes maintain the 500V voltage rating, -55°C to 150°C operating temperature range, and RoHS3/REACH compliance required for regulatory conformance.

Frequently Asked Questions (FAQ)

Q: Can the IXFK80N50Q3 be used as a direct replacement for the IXFK66N50Q2?

A: Yes. The IXFK80N50Q3 uses the identical TO-264AA package and maintains the same 500V voltage rating and -55°C to 150°C operating temperature range. The higher current rating (80A vs. 66A) and lower on-state resistance (65 mOhm vs. 80 mOhm) provide improved performance without circuit modification. No PCB redesign is required.

Q: What is the difference between the IXFK80N50Q3 and APT75F50B2?

A: Both parts meet the voltage and temperature requirements of the IXFK66N50Q2. The IXFK80N50Q3 offers higher current capability (80A vs. 75A) and lower on-state resistance (65 mOhm vs. 75 mOhm). The APT75F50B2 uses a T-MAX™ [B2] package instead of TO-264AA, requiring PCB layout verification. Both are active products with full compliance certifications.

Q: Does the higher gate charge of the APT75F50B2 affect circuit performance?

A: The APT75F50B2 has a gate charge of 290 nC compared to 200 nC for the IXFK66N50Q2. This affects gate drive circuit timing and power consumption but does not prevent substitution. Gate drive circuits must be verified to ensure adequate drive capability at the intended switching frequency.

Q: Are there package compatibility concerns when substituting the APT75F50B2?

A: The APT75F50B2 uses a T-MAX™ [B2] package, which is a through-hole variant of the TO-247-3 family. While mechanically similar to TO-264AA, the exact pin spacing and mounting hole positions differ. PCB layout verification is required before substitution to confirm mechanical fit and thermal interface compatibility.

Q: Why is the IXFK66N50Q2 classified as obsolete?

A: The IXFK66N50Q2 is an older generation HiPerFET™ device. IXYS has transitioned to newer product lines such as the Q3 class (IXFK80N50Q3), which offer improved electrical performance and higher power dissipation ratings. Obsolete classification indicates that the original part is no longer manufactured, making substitution necessary for new designs and ongoing production.

Q: Can both substitute parts handle the same thermal load as the original IXFK66N50Q2?

A: Both substitute parts have higher power dissipation ratings (1250W for IXFK80N50Q3 and 1040W for APT75F50B2) compared to the original (735W). This provides additional thermal margin. However, actual thermal performance depends on PCB copper area, heat sink design, and ambient conditions. Thermal analysis should be performed for the specific application.

Q: What compliance certifications do the substitute parts maintain?

A: Both the IXFK80N50Q3 and APT75F50B2 are RoHS3 compliant and REACH unaffected, matching the compliance status of the original IXFK66N50Q2. Both parts are suitable for applications requiring regulatory compliance in electronics manufacturing.

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