FQP4N50 Equivalent & Substitute Parts

Part Overview

The FQP4N50 is an N-Channel MOSFET manufactured by onsemi, rated for 500V drain-to-source voltage with a continuous drain current of 3.4A at 25°C. This device is packaged in a TO-220-3 through-hole configuration and is rated for 70W power dissipation. The FQP4N50 is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and procurement continuity.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	3.4	A
Power Dissipation (Max)	70	W
Rds On (Max) @ 10V	2.7	Ohm
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	—
Package	TO-220-3	—

Substitute Part Grouping Explanation

Substitution of the FQP4N50 is determined by the following critical parameters:

Electrical Compatibility Requirements:

FET Type: N-Channel (required match)
Drain to Source Voltage (Vdss): Minimum 500V (equal or higher acceptable)
Continuous Drain Current (Id): Minimum 3.4A (equal or higher acceptable)
Gate Drive Voltage: 10V (standard drive voltage)
Gate Threshold Voltage (Vgs(th)): Within ±30V maximum gate voltage specification
Operating Temperature Range: -55°C to 150°C (minimum requirement)

Mechanical Compatibility Requirements:

Mounting Type: Through Hole (required match)
Package Type: TO-220 family packages acceptable (TO-220-3, TO-220AB, or equivalent pin-compatible configurations)

The substitute parts listed below meet or exceed these electrical and mechanical parameters, enabling direct or near-direct replacement in applications designed for the FQP4N50.

Parameter Comparison

Parameter	FQP4N50 (onsemi)	STP5NK50Z (STMicroelectronics)	STU4N52K3 (STMicroelectronics)
FET Type	N-Channel	N-Channel	N-Channel
Drain to Source Voltage (Vdss)	500 V	500 V	525 V
Continuous Drain Current (Id) @ 25°C	3.4 A	4.4 A	2.5 A
Power Dissipation (Max)	70 W	70 W	45 W
Rds On (Max) @ 10V	2.7 Ohm	1.5 Ohm	2.6 Ohm
Vgs(th) (Max) @ Id	5 V @ 250µA	4.5 V @ 50µA	4.5 V @ 50µA
Gate Charge (Qg) (Max) @ 10V	13 nC	28 nC	11 nC
Input Capacitance (Ciss) (Max)	460 pF @ 25 V	535 pF @ 25 V	334 pF @ 100 V
Vgs (Max)	±30 V	±30 V	±30 V
Operating Temperature Range	-55 to 150 °C	-55 to 150 °C	-55 to 150 °C
Mounting Type	Through Hole	Through Hole	Through Hole
Package	TO-220-3	TO-220	I-PAK (TO-251-3)
Product Status	Obsolete	Active	Active

Engineering Selection Recommendations

STP5NK50Z (STMicroelectronics): This substitute provides direct electrical and mechanical compatibility with the FQP4N50. The STP5NK50Z meets or exceeds all critical parameters: 500V Vdss, 4.4A continuous drain current (exceeds 3.4A requirement), and 70W power dissipation. The device is packaged in TO-220 configuration, compatible with TO-220-3 footprints. The STP5NK50Z is classified as Active product status with RoHS3 compliance, ensuring long-term availability and regulatory alignment. The lower on-resistance (1.5 Ohm vs. 2.7 Ohm) provides improved thermal performance.

STU4N52K3 (STMicroelectronics): This substitute is suitable for applications where the FQP4N50 operates below 2.5A continuous drain current. The STU4N52K3 exceeds the voltage rating (525V vs. 500V) and maintains compatible gate drive characteristics. However, the reduced power dissipation rating (45W vs. 70W) and lower continuous drain current (2.5A vs. 3.4A) limit its applicability to lower-power designs. The I-PAK package (TO-251-3) differs mechanically from the TO-220-3 footprint, requiring PCB layout modification. The device is Active with RoHS3 compliance.

Both substitute parts are manufactured by STMicroelectronics and carry REACH Unaffected and EAR99 classifications, matching the regulatory profile of the original FQP4N50.

Frequently Asked Questions (FAQ)

Q: Can the STP5NK50Z directly replace the FQP4N50 without PCB modifications?

A: Yes. The STP5NK50Z is packaged in TO-220 configuration, which is pin-compatible with the TO-220-3 footprint of the FQP4N50. No PCB layout changes are required for this substitution.

Q: What is the primary advantage of the STP5NK50Z over the FQP4N50?

A: The STP5NK50Z offers lower on-resistance (1.5 Ohm vs. 2.7 Ohm at 10V gate drive), resulting in reduced power dissipation and improved thermal efficiency in the same 70W power rating. The device is also Active product status, ensuring continued availability.

Q: Is the STU4N52K3 suitable for all FQP4N50 applications?

A: No. The STU4N52K3 is limited to applications where continuous drain current does not exceed 2.5A and power dissipation remains below 45W. Applications requiring the full 3.4A rating or 70W dissipation require the STP5NK50Z. Additionally, the I-PAK package requires PCB redesign.

Q: What are the key electrical parameters that determine substitution compatibility?

A: The critical parameters are: N-Channel FET type, minimum 500V Vdss, minimum 3.4A continuous drain current at 25°C, ±30V gate voltage tolerance, and -55°C to 150°C operating temperature range. All substitute parts meet these requirements.

Q: Are there package considerations when selecting a substitute?

A: Yes. The STP5NK50Z uses TO-220 packaging, compatible with existing TO-220-3 PCB layouts. The STU4N52K3 uses I-PAK (TO-251-3) packaging, which requires PCB footprint modification and is not a direct drop-in replacement.

Q: What is the regulatory and compliance status of the substitute parts?

A: Both STP5NK50Z and STU4N52K3 are RoHS3 compliant, REACH Unaffected, and classified as EAR99 for export control purposes, matching the regulatory profile of the FQP4N50.

Q: Why is the FQP4N50 classified as obsolete?

A: The FQP4N50 is no longer in active production by onsemi. The substitute parts from STMicroelectronics provide equivalent or superior performance with Active product status, ensuring long-term design support and procurement availability.

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