IXTQ42N25P N-Channel MOSFET 250V 42A Equivalent & Substitute Parts

Part Overview

The IXTQ42N25P is an N-Channel MOSFET manufactured by IXYS, rated for 250V drain-to-source voltage with 42A continuous drain current at 25°C. This device is housed in a TO-3P package and is designed for through-hole mounting applications requiring high-current switching at elevated voltage levels. The part is currently in active production status with 1329 units in stock.

Substitute parts become necessary when the primary device reaches end-of-life status, experiences supply constraints, or when design requirements permit operation within the electrical and mechanical parameters of alternative qualified devices. The FDA33N25 from onsemi is identified as a functional equivalent based on matching voltage ratings, package compatibility, and thermal operating range.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	250	V
Continuous Drain Current (Id) @ 25°C	42	A
Drive Voltage (Max Rds On)	10	V
On-State Resistance (Rds On Max) @ 10V	84	mOhm
Gate Threshold Voltage (Vgs th Max) @ 250µA	5.5	V
Gate Charge (Qg Max) @ 10V	70	nC
Maximum Gate Voltage (Vgs Max)	±20	V
Input Capacitance (Ciss Max) @ 25V	2300	pF
Power Dissipation (Max)	300	W
Operating Temperature Range	-55 to 150	°C
Package Type	TO-3P	—
Mounting Type	Through Hole	—

Substitute Part Grouping Explanation

Substitution of the IXTQ42N25P with the FDA33N25 is permissible based on the following matching electrical and mechanical parameters:

Matching Parameters:

Drain-to-Source Voltage (Vdss): Both rated at 250V
FET Type: Both N-Channel MOSFETs
Technology: Both Metal Oxide Semiconductor technology
Operating Temperature Range: Both -55°C to 150°C
Package Compatibility: Both use TO-3P package family (TO-3P-3, SC-65-3)
Mounting Type: Both through-hole configuration
Drive Voltage: Both specified at 10V for maximum Rds On rating
RoHS Compliance: Both ROHS3 compliant
REACH Status: Both REACH unaffected

Differing Parameters: The FDA33N25 has a lower continuous drain current rating (33A versus 42A) and reduced power dissipation (245W versus 300W). These differences establish the substitution as a downgrade in current-handling capacity and thermal performance. The FDA33N25 is suitable only for applications where the required drain current does not exceed 33A and thermal dissipation remains within 245W limits.

Parameter Comparison

Parameter	IXTQ42N25P (IXYS)	FDA33N25 (onsemi)	Unit
Drain-to-Source Voltage (Vdss)	250	250	V
Continuous Drain Current (Id) @ 25°C	42	33	A
Drive Voltage (Max Rds On)	10	10	V
On-State Resistance (Rds On Max) @ 10V	84	94	mOhm
Gate Threshold Voltage (Vgs th Max) @ 250µA	5.5	5	V
Gate Charge (Qg Max) @ 10V	70	46.8	nC
Maximum Gate Voltage (Vgs Max)	±20	±30	V
Input Capacitance (Ciss Max) @ 25V	2300	2200	pF
Power Dissipation (Max)	300	245	W
Operating Temperature Range	-55 to 150	-55 to 150	°C
Package Type	TO-3P	TO-3PN	—
Product Status	Active	Obsolete	—

Engineering Selection Recommendations

Primary Part (IXTQ42N25P): The IXTQ42N25P remains the preferred selection for new designs and applications requiring the full 42A continuous drain current rating and 300W power dissipation capability. This device is in active production status, ensuring long-term availability and supply continuity. Full RoHS3 compliance and REACH unaffected status confirm regulatory alignment for current and future applications.

Substitute Part (FDA33N25): The FDA33N25 is classified as obsolete and should be used only in legacy system maintenance or repair scenarios where the original part specification is no longer available. This device is suitable exclusively for applications where the required drain current does not exceed 33A and thermal dissipation remains below 245W. The higher maximum gate voltage rating (±30V versus ±20V) provides additional gate drive margin in certain circuit topologies. Selection of this substitute requires explicit confirmation that application requirements fall within the reduced current and power ratings.

Frequently Asked Questions (FAQ)

Q: Can the FDA33N25 be used as a direct replacement for the IXTQ42N25P in all applications?

A: No. The FDA33N25 has a lower continuous drain current rating (33A versus 42A) and reduced maximum power dissipation (245W versus 300W). Direct substitution is permissible only in applications where the actual operating drain current does not exceed 33A and thermal dissipation remains within 245W limits. Applications requiring the full 42A rating must use the IXTQ42N25P.

Q: Are the TO-3P and TO-3PN packages mechanically compatible?

A: Both devices use the TO-3P package family (TO-3P-3, SC-65-3) designation. Mechanical compatibility for PCB mounting and thermal interface applications is established. Pin configuration and lead spacing are compatible for through-hole mounting applications.

Q: What is the significance of the FDA33N25 being classified as obsolete?

A: Obsolete status indicates the FDA33N25 is no longer in active production. This part should be used only for repair and maintenance of existing systems. New designs must specify the IXTQ42N25P or identify alternative active-status devices that meet application requirements.

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

A: The IXTQ42N25P has an on-state resistance of 84 mOhm at 10V gate drive, while the FDA33N25 has 94 mOhm under the same conditions. The higher resistance in the FDA33N25 results in increased conduction losses and heat generation at equivalent current levels.

Q: Are both devices RoHS compliant?

A: Yes. Both the IXTQ42N25P and FDA33N25 are ROHS3 compliant and REACH unaffected, confirming regulatory alignment for applications subject to these standards.

Q: What is the difference in gate charge between these devices?

A: The IXTQ42N25P has a maximum gate charge of 70 nC at 10V, while the FDA33N25 has 46.8 nC. The lower gate charge in the FDA33N25 results in faster switching transitions and reduced gate drive power requirements.

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