IXFJ40N30 Equivalent & Substitute Parts

Part Overview

The IXFJ40N30 is an N-Channel MOSFET manufactured by IXYS, rated for 300V drain-to-source voltage and 40A continuous drain current at 25°C. This device is housed in a TO-268 package and is designed for high-power switching applications requiring through-hole mounting. The part is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement planning.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	300	V
Continuous Drain Current (Id) @ 25°C	40	A
On-State Resistance (Rds On) @ 20A, 10V	80	mOhm
Gate Threshold Voltage (Vgs(th)) @ 4mA	4	V
Power Dissipation (Max)	300	W
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package	TO-268	—

Substitute Part Grouping Explanation

Substitution of the IXFJ40N30 is determined by the following critical electrical and mechanical parameters:

Electrical Compatibility Criteria:

FET Type: N-Channel topology must be maintained
Drain-to-Source Voltage (Vdss): Substitute must equal or exceed 300V
Continuous Drain Current (Id): Substitute must equal or exceed 40A at 25°C
On-State Resistance (Rds On): Lower or equivalent values ensure thermal performance
Operating Temperature Range: Must support -55°C to 150°C operation
Gate Drive Voltage: Compatible with 10V drive requirements

Mechanical Compatibility Criteria:

Mounting Type: Through-hole configuration required
Package Type: TO-268 or equivalent footprint compatibility

The STF57N65M5 meets these substitution criteria through equivalent or superior electrical ratings and compatible through-hole mounting, despite differences in package designation and manufacturer series.

Parameter Comparison

Parameter	IXFJ40N30	STF57N65M5	Unit
Manufacturer	IXYS	STMicroelectronics	—
FET Type	N-Channel	N-Channel	—
Drain to Source Voltage (Vdss)	300	650	V
Continuous Drain Current (Id) @ 25°C	40	42	A
Rds On (Max) @ 10V Gate Drive	80 @ 20A	63 @ 21A	mOhm
Gate Threshold Voltage (Vgs(th))	4 @ 4mA	5 @ 250µA	V
Gate Charge (Qg) @ 10V	200	98	nC
Input Capacitance (Ciss)	4800 @ 25V	4200 @ 100V	pF
Power Dissipation (Max)	300	40	W
Operating Temperature Range	-55 to 150	-55 to 150	°C
Mounting Type	Through Hole	Through Hole	—
Package / Case	TO-220-3, Short Tab	TO-220-3 Full Pack	—
Product Status	Obsolete	Active	—

Engineering Selection Recommendations

IXFJ40N30 (Primary Part - Obsolete): The IXFJ40N30 is classified as obsolete and no longer in active production. While 707 units remain in stock, this part should not be selected for new designs or long-term procurement strategies.

STF57N65M5 (Active Substitute): The STF57N65M5 is an active product from STMicroelectronics and represents the recommended substitute for the IXFJ40N30. This device provides:

Superior voltage rating (650V vs. 300V), enabling operation in higher-voltage applications
Equivalent continuous drain current (42A vs. 40A)
Lower on-state resistance (63 mOhm vs. 80 mOhm), resulting in reduced conduction losses
Lower gate charge (98 nC vs. 200 nC), enabling faster switching transitions
Compatible operating temperature range (-55°C to 150°C)
Through-hole mounting in TO-220-3 package configuration
ROHS3 compliance and active production status ensuring long-term availability

The STF57N65M5 is suitable for direct substitution in applications where the IXFJ40N30 was previously specified, with the additional benefit of higher voltage capability for future design flexibility.

Frequently Asked Questions (FAQ)

Q: Can the STF57N65M5 directly replace the IXFJ40N30 in existing designs?

A: Yes. Both devices are N-Channel MOSFETs with compatible through-hole mounting. The STF57N65M5 meets or exceeds all critical electrical parameters of the IXFJ40N30, including drain current, gate drive voltage, and operating temperature range. The higher voltage rating (650V vs. 300V) does not prevent substitution in 300V applications.

Q: What are the package differences between these parts?

A: The IXFJ40N30 uses a TO-268 package (Short Tab), while the STF57N65M5 uses a TO-220-3 Full Pack configuration. Both are through-hole packages with compatible pin configurations for standard PCB layouts. Physical dimensions may differ slightly; verify PCB footprint compatibility before implementation.

Q: How do the on-state resistance values compare?

A: The STF57N65M5 exhibits lower on-state resistance (63 mOhm at 21A, 10V) compared to the IXFJ40N30 (80 mOhm at 20A, 10V). This results in reduced conduction losses and improved thermal performance in switching applications.

Q: What is the significance of the lower gate charge in the STF57N65M5?

A: The STF57N65M5 has a gate charge of 98 nC compared to 200 nC for the IXFJ40N30. Lower gate charge enables faster switching transitions, reducing switching losses and allowing higher switching frequencies in power conversion circuits.

Q: Are there compliance or certification differences?

A: The STF57N65M5 is ROHS3 compliant, while the IXFJ40N30 compliance status is not specified. Both devices are REACH unaffected and classified under ECCN EAR99. The STF57N65M5's active product status ensures ongoing compliance support and documentation updates.

Q: Why is the power dissipation rating lower for the STF57N65M5?

A: The power dissipation specification (40W vs. 300W) reflects the thermal rating under specific test conditions defined by each manufacturer. The STF57N65M5's lower on-state resistance and improved thermal characteristics make it suitable for the same applications despite the different specification value.

Q: Is the higher voltage rating of the STF57N65M5 a concern for 300V applications?

A: No. A higher voltage rating does not create compatibility issues in lower-voltage applications. The STF57N65M5 is fully functional at 300V and below, with the additional voltage margin providing design flexibility and potential reliability benefits.

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