IXTH21N50 Equivalent & Substitute Parts

Part Overview

The IXTH21N50 is an N-Channel 500V 21A MOSFET manufactured by IXYS in the MegaMOS™ series, housed in a TO-247 through-hole package. This device is rated for 300W power dissipation and operates across a temperature range of -55°C to 150°C. The part is designated as Last Time Buy, indicating that the original manufacturer has ceased production and existing inventory represents the final availability from the original source.

Substitute parts are necessary when the IXTH21N50 reaches end-of-life or when inventory becomes depleted. Alternative N-Channel 500V MOSFETs with comparable electrical characteristics and identical TO-247 packaging provide functional equivalence for applications requiring this voltage and current rating.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	21	A
Rds On (Max) @ 10.5A, 10V	250	mOhm
Gate Charge (Qg) @ 10V	190	nC
Power Dissipation (Max)	300	W
Operating Temperature Range	-55 to 150	°C
Package Type	TO-247	—
Mounting Type	Through Hole	—

Substitute Part Grouping Explanation

Substitution of the IXTH21N50 is determined by the following critical parameters:

Mandatory Matching Criteria:

Drain to Source Voltage (Vdss): 500V minimum
Package Type: TO-247 through-hole configuration
FET Type: N-Channel
Technology: Metal Oxide MOSFET
Operating Temperature Range: -55°C to 150°C minimum

Performance Compatibility Criteria:

Continuous Drain Current (Id): Equal to or greater than 21A
Rds On (Max): Equal to or less than 250mOhm at specified gate voltage
Power Dissipation: Equal to or greater than 300W
Gate Charge (Qg): Lower values indicate faster switching performance

Substitute parts are grouped into two categories: Manufacturer Recommended substitutes (direct replacements from IXYS with enhanced specifications) and Similar substitutes (alternative manufacturers offering equivalent electrical performance in the same package).

Parameter Comparison

Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On Max (mOhm)	Qg @ 10V (nC)	Power Diss (W)	Package	Status
IXTH21N50	IXYS	500	21	250	190	300	TO-247	Last Time Buy
IXTH22N50P	IXYS	500	22	270	50	350	TO-247	Active
IXFH22N50P	IXYS	500	22	270	50	350	TO-247	Active
IPW50R140CPFKSA1	Infineon Technologies	550	23	140	64	192	TO-247	Last Time Buy
IPW50R250CPFKSA1	Infineon Technologies	500	13	250	36	114	TO-247	Active
IRFP448PBF	Vishay Siliconix	500	11	600	84	180	TO-247	Active
STW19NM50N	STMicroelectronics	500	14	250	34	110	TO-247	Active
STW20NK50Z	STMicroelectronics	500	17	270	119	190	TO-247	Active

Engineering Selection Recommendations

Tier 1 - Manufacturer Recommended Substitutes (IXYS):

The IXTH22N50P and IXFH22N50P are the primary substitutes for the IXTH21N50. Both parts are manufactured by IXYS and maintain the 500V Vdss rating with increased current capability (22A versus 21A). The IXTH22N50P is designated as Active product status, ensuring continued availability and manufacturing support. The IXFH22N50P operates in the HiPerFET™ and Polar series with identical electrical specifications to the IXTH22N50P but uses the TO-247AD package variant. Both parts exceed the original 300W power dissipation requirement with 350W ratings and feature significantly reduced gate charge (50nC versus 190nC), enabling faster switching performance. All parts maintain RoHS3 compliance and MSL Level 1 moisture sensitivity.

Tier 2 - Alternative Manufacturer Substitutes:

The STW20NK50Z (STMicroelectronics) provides the closest current rating match at 17A with 500V Vdss and 270mOhm Rds On, maintaining compatibility with the original design envelope. This part is Active status with 7794 units in stock, providing supply security.

The IPW50R250CPFKSA1 (Infineon Technologies CoolMOS™) matches the 500V Vdss and 250mOhm Rds On specifications but operates at reduced current (13A). This part is suitable for applications where the full 21A rating is not required.

Parts Not Recommended for Direct Substitution:

The IRFP448PBF exhibits 600mOhm Rds On, which exceeds the original 250mOhm specification and results in higher conduction losses. The IPW50R140CPFKSA1, while offering superior Rds On performance (140mOhm), is designated Last Time Buy status and provides reduced power dissipation (192W versus 300W).

All substitute parts maintain identical operating temperature ranges (-55°C to 150°C), RoHS3 compliance, and MSL Level 1 ratings as the original IXTH21N50.

Frequently Asked Questions (FAQ)

Q: Can the IXTH22N50P directly replace the IXTH21N50 in existing designs?

A: Yes. The IXTH22N50P is the manufacturer-recommended substitute. It maintains the 500V Vdss rating, TO-247 package, and through-hole mounting configuration. The increased current rating (22A versus 21A) and power dissipation (350W versus 300W) provide enhanced performance margins. Gate charge is significantly reduced (50nC versus 190nC), which may require verification of gate drive circuit timing in high-frequency switching applications.

Q: What is the difference between IXTH22N50P and IXFH22N50P?

A: Both parts share identical electrical specifications (500V, 22A, 270mOhm Rds On, 350W). The primary difference is the package designation: IXTH22N50P uses TO-247 (IXTH) while IXFH22N50P uses TO-247AD (IXFH). The TO-247AD variant features an isolated drain tab. Mechanical compatibility with existing PCB layouts and heatsink mounting must be verified before substitution.

Q: Why does the IRFP448PBF have higher Rds On than the IXTH21N50?

A: The IRFP448PBF is rated at 11A continuous current, which is lower than the IXTH21N50 (21A). The higher Rds On value (600mOhm versus 250mOhm) reflects the different design optimization for lower current applications. This part is not suitable for applications requiring the full 21A rating due to increased conduction losses and thermal dissipation.

Q: Is the STW20NK50Z suitable for applications requiring 21A continuous current?

A: The STW20NK50Z is rated for 17A continuous current, which is below the IXTH21N50 specification of 21A. This part is suitable only for applications where the actual operating current does not exceed 17A. For designs requiring the full 21A rating, the IXTH22N50P or IXFH22N50P are the appropriate selections.

Q: What is the significance of the Last Time Buy status for the IXTH21N50?

A: Last Time Buy designation indicates that IXYS has ceased production of this part. The 13488 units currently in stock represent the final available inventory. Once depleted, the part will no longer be available from the manufacturer. Designers should transition to the IXTH22N50P (Active status) for new designs and long-term production requirements.

Q: Can I use the IPW50R250CPFKSA1 as a substitute if my application only requires 13A?

A: Yes, provided the application current does not exceed 13A. The IPW50R250CPFKSA1 matches the 500V Vdss and 250mOhm Rds On specifications of the IXTH21N50. However, this part is designated Active status and provides lower power dissipation (114W versus 300W), which may limit thermal margin in high-duty-cycle applications.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All substitute parts listed maintain RoHS3 compliance and MSL Level 1 moisture sensitivity ratings, matching the environmental and regulatory compliance of the original IXTH21N50.

Q: What should I verify before implementing a substitute part?

A: Verify gate drive circuit compatibility, particularly gate charge differences (ranging from 34nC to 190nC across substitutes). Confirm PCB layout and heatsink mounting compatibility with the selected package variant (TO-247 versus TO-247AD). Validate that the application's actual operating current does not exceed the substitute part's continuous drain current rating. Confirm thermal management adequacy based on the substitute part's power dissipation rating and Rds On characteristics.

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