IXFH40N50Q2 N-Channel 500V 40A MOSFET Equivalent & Substitute Parts

Part Overview

The IXFH40N50Q2 is an N-Channel metal oxide semiconductor field-effect transistor (MOSFET) rated for 500V drain-to-source voltage and 40A continuous drain current at 25°C. This device is part of the IXYS HiPerFET™ series and is housed in a TO-247AD through-hole package. The part is currently classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing system support and new design considerations where similar performance characteristics are required.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	40	A
On-State Resistance (Rds On) @ 500mA, 10V	160	mOhm
Gate Threshold Voltage (Vgs(th)) @ 4mA	4.5	V
Gate Charge (Qg) @ 10V	110	nC
Input Capacitance (Ciss) @ 25V	4850	pF
Power Dissipation (Max)	560	W
Operating Temperature Range	-55 to 150	°C
Package Type	TO-247AD	Through Hole
FET Type	N-Channel

Substitute Part Grouping Explanation

Substitution of the IXFH40N50Q2 is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-to-Source Voltage (Vdss): Must equal or exceed 500V
Continuous Drain Current (Id): Must equal or exceed 40A at 25°C
Gate Drive Voltage: Must support 10V operation
Package Type: Must be through-hole TO-247 variant
FET Type: Must be N-Channel metal oxide technology
Operating Temperature Range: Must support -55°C to 150°C minimum

Secondary Compatibility Parameters:

On-State Resistance (Rds On): Lower values indicate improved performance
Gate Charge (Qg): Lower values reduce switching losses
Input Capacitance (Ciss): Affects gate drive requirements
Power Dissipation Rating: Must accommodate application thermal requirements

Substitute parts are grouped based on whether they meet or exceed the primary criteria while maintaining electrical compatibility within the specified operating envelope.

Parameter Comparison

Parameter	IXFH40N50Q2	IXFH44N50Q3	APT42F50B	STW20NM50FD	STW26NM50	STW28NM50N	STW32NM50N
Vdss (V)	500	500	500	500	500	500	500
Id @ 25°C (A)	40	44	42	20	30	21	22
Rds On (mOhm)	160 @ 500mA	140 @ 22A	130 @ 21A	250 @ 10A	120 @ 13A	158 @ 10.5A	130 @ 11A
Vgs(th) (V)	4.5	6.5	5	5	5	4	4
Qg @ 10V (nC)	110	93	170	53	106	50	62.5
Ciss @ 25V (pF)	4850	4800	6810	1380	3000	1735	1973
Power Dissipation (W)	560	830	625	214	313	150	190
Operating Temp (°C)	-55 to 150	-55 to 150	-55 to 150	to 150	to 150	to 150	to 150
Package	TO-247AD	TO-247AD	TO-247 [B]	TO-247-3	TO-247-3	TO-247-3	TO-247-3
Product Status	Obsolete	Active	Active	Active	Not For New Designs	Active	Active

Engineering Selection Recommendations

Direct Equivalent (Preferred):

The IXFH44N50Q3 is the primary equivalent for the IXFH40N50Q2. Both devices are manufactured by IXYS within the HiPerFET™ series and share identical voltage ratings (500V Vdss) and package type (TO-247AD). The IXFH44N50Q3 exceeds the current rating (44A vs. 40A) and provides superior power dissipation capability (830W vs. 560W). The device is classified as Active with RoHS3 compliance, ensuring long-term availability and regulatory alignment. Gate charge is reduced (93nC vs. 110nC), resulting in lower switching losses.

Secondary Equivalent (Microchip Alternative):

The APT42F50B from Microchip Technology meets all primary substitution criteria with 500V Vdss, 42A continuous drain current, and TO-247 through-hole packaging. This device is Active and RoHS3 compliant. The on-state resistance is superior (130mOhm vs. 160mOhm), though gate charge is higher (170nC vs. 110nC), requiring evaluation of gate drive circuit capability.

Lower Current Alternatives (Derating Applications):

The STW28NM50N and STW32NM50N from STMicroelectronics are suitable for applications where continuous drain current requirements are reduced. Both are Active, RoHS3 compliant, and feature lower gate charge (50nC and 62.5nC respectively), reducing switching losses. These devices are appropriate for designs operating below 40A continuous current.

Not Recommended for Direct Substitution:

The STW20NM50FD and STW26NM50 do not meet the minimum 40A continuous drain current requirement of the IXFH40N50Q2. The STW26NM50 is classified as "Not For New Designs," limiting its suitability for ongoing system support.

Frequently Asked Questions (FAQ)

Q: Can the IXFH44N50Q3 directly replace the IXFH40N50Q2 in existing designs?

A: Yes. The IXFH44N50Q3 meets all primary electrical and mechanical substitution criteria. Both devices operate at 500V Vdss, support 10V gate drive, and use the TO-247AD through-hole package. The IXFH44N50Q3 provides higher current rating (44A vs. 40A) and improved power dissipation (830W vs. 560W), making it functionally superior. Pin configuration and thermal characteristics are compatible.

Q: What is the significance of the different TO-247 package variants (TO-247AD vs. TO-247 [B] vs. TO-247-3)?

A: All variants are through-hole TO-247 packages with identical pin spacing and mounting footprints. The designations reflect manufacturer-specific package specifications. TO-247AD (IXYS), TO-247 [B] (Microchip), and TO-247-3 (STMicroelectronics) are mechanically and electrically interchangeable in PCB layouts designed for standard TO-247 through-hole mounting.

Q: Why do some substitute parts have lower continuous drain current ratings?

A: The STW20NM50FD (20A), STW26NM50 (30A), STW28NM50N (21A), and STW32NM50N (22A) are not direct equivalents for the 40A IXFH40N50Q2. These parts are listed as alternatives only for applications where the design current requirement is lower than 40A. Selecting a device with insufficient current rating will result in thermal stress and potential failure.

Q: How does on-state resistance (Rds On) affect device selection?

A: Lower Rds On values reduce conduction losses and heat generation. The IXFH44N50Q3 (140mOhm) and APT42F50B (130mOhm) provide superior efficiency compared to the IXFH40N50Q2 (160mOhm). However, Rds On is measured at different current levels across devices, requiring normalized comparison at the application's operating point.

Q: What is the importance of gate charge (Qg) in substitution decisions?

A: Gate charge determines the energy required to switch the device on and off. Lower Qg values reduce switching losses and allow faster switching speeds. The IXFH44N50Q3 (93nC) and STW28NM50N (50nC) have lower gate charge than the IXFH40N50Q2 (110nC), improving efficiency in high-frequency applications. Gate drive circuits must supply sufficient current to charge the gate within the required switching time.

Q: Are there compliance or regulatory differences between substitute parts?

A: All listed substitute parts are RoHS3 compliant and REACH unaffected, meeting current regulatory requirements. The IXFH40N50Q2 is classified as Obsolete, while IXFH44N50Q3, APT42F50B, STW28NM50N, and STW32NM50N are Active, ensuring continued availability and support. The STW26NM50 is classified as "Not For New Designs," limiting its use in new product development.

Q: Can input capacitance (Ciss) differences affect circuit performance?

A: Input capacitance affects gate drive circuit impedance and switching transient behavior. The IXFH40N50Q2 has Ciss of 4850pF, while substitutes range from 1380pF (STW20NM50FD) to 6810pF (APT42F50B). Higher Ciss requires greater gate drive current; lower Ciss reduces gate drive requirements. Gate drive circuits must be evaluated for compatibility with the selected device's capacitance.

Q: What thermal considerations apply when selecting a substitute?

A: Power dissipation ratings indicate maximum thermal capability. The IXFH40N50Q2 is rated for 560W, while the IXFH44N50Q3 supports 830W. Applications with high switching frequency or continuous high current operation benefit from devices with higher power dissipation ratings. Thermal management (heatsinking, PCB layout) must accommodate the selected device's power dissipation in the specific application environment.

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