FQP6N40CF N-Channel MOSFET Equivalent & Substitute Parts

Part Overview

The FQP6N40CF is an N-Channel MOSFET manufactured by onsemi, rated for 400V drain-to-source voltage with 6A continuous drain current at 25°C. This device is packaged in a Through Hole TO-220-3 configuration and is part of the FRFET® series. The FQP6N40CF is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility across voltage, current, and thermal specifications while accommodating packaging and compliance requirements.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	400	V
Continuous Drain Current (Id) @ 25°C	6	A
On-State Resistance (Rds On Max) @ Id, Vgs	1.1	Ohm @ 3A, 10V
Gate Threshold Voltage (Vgs(th) Max) @ Id	4	V @ 250µA
Gate Charge (Qg Max) @ Vgs	20	nC @ 10V
Maximum Gate Voltage (Vgs Max)	±30	V
Input Capacitance (Ciss Max) @ Vds	625	pF @ 25V
Power Dissipation (Max)	73	W
Operating Temperature Range	-55 to 150	°C
Mounting Type	Through Hole	-
Package / Case	TO-220-3	-
RoHS Status	ROHS3 Compliant	-

Substitute Part Grouping Explanation

Substitution of the FQP6N40CF is determined by the following critical electrical and mechanical parameters:

Voltage Rating Compatibility: Substitute parts must maintain a Vdss rating equal to or greater than 400V to ensure safe operation in the original circuit topology.

Current Rating Compatibility: Substitute parts must support continuous drain current (Id) at or above 6A at 25°C to meet or exceed the thermal and load-handling requirements of the original design.

On-State Resistance (Rds On): Substitute parts must maintain comparable Rds On values to ensure similar power dissipation characteristics and switching performance.

Gate Voltage Specifications: Substitute parts must accommodate the gate threshold voltage (Vgs(th)) and maximum gate voltage (Vgs Max) ranges to ensure proper gate drive compatibility.

Thermal Performance: Substitute parts must support power dissipation at or above 73W to maintain thermal margin in the application.

Package Compatibility: Substitute parts must use Through Hole TO-220 package variants to ensure mechanical and thermal interface compatibility with existing PCB designs.

Compliance Requirements: Substitute parts should maintain RoHS3 compliance and REACH unaffected status where possible to align with regulatory and supply chain requirements.

Parameter Comparison

Parameter	FQP6N40CF (Main)	IRF734 (Substitute)	STP7NK40Z (Substitute)
Manufacturer	onsemi	Vishay Siliconix	STMicroelectronics
Drain to Source Voltage (Vdss)	400V	450V	400V
Continuous Drain Current (Id) @ 25°C	6A	4.9A	5.4A
Rds On (Max) @ Id, Vgs	1.1Ω @ 3A, 10V	1.2Ω @ 2.9A, 10V	1Ω @ 2.7A, 10V
Vgs(th) (Max) @ Id	4V @ 250µA	4V @ 250µA	4.5V @ 50µA
Gate Charge (Qg Max) @ Vgs	20nC @ 10V	45nC @ 10V	26nC @ 10V
Vgs (Max)	±30V	±20V	±30V
Input Capacitance (Ciss Max) @ Vds	625pF @ 25V	680pF @ 25V	535pF @ 25V
Power Dissipation (Max)	73W	74W	70W
Operating Temperature Range	-55 to 150°C	-55 to 150°C	-55 to 150°C
Package / Case	TO-220-3	TO-220AB	TO-220
Product Status	Obsolete	Active	Active
RoHS Status	ROHS3 Compliant	RoHS non-compliant	ROHS3 Compliant

Engineering Selection Recommendations

STP7NK40Z (Primary Substitute): This STMicroelectronics device is the preferred substitute for the FQP6N40CF. It maintains identical Vdss rating (400V), supports 5.4A continuous drain current, and delivers superior on-state resistance performance (1Ω vs. 1.1Ω). The STP7NK40Z is classified as Active product status, ensuring long-term availability and supply chain stability. It maintains ROHS3 compliance and REACH unaffected status, aligning with the original part's regulatory profile. Gate charge is slightly elevated (26nC vs. 20nC), but remains within acceptable switching performance parameters. The TO-220 package is mechanically compatible with TO-220-3 footprints in standard PCB designs.

IRF734 (Secondary Substitute): The Vishay Siliconix IRF734 provides an alternative with elevated voltage rating (450V) and comparable power dissipation (74W). However, this device exhibits reduced continuous drain current (4.9A vs. 6A), which may limit its application in designs requiring full 6A operation. The IRF734 carries RoHS non-compliant status, which may conflict with procurement requirements in regulated industries. Gate charge is significantly elevated (45nC vs. 20nC), potentially affecting switching speed and gate drive circuit design. Maximum gate voltage is reduced to ±20V, requiring verification against gate drive specifications. The IRF734 is suitable only for applications where the lower current rating and compliance status do not present constraints.

Frequently Asked Questions (FAQ)

Q: Can the STP7NK40Z directly replace the FQP6N40CF in existing designs?

A: Yes. The STP7NK40Z maintains the same 400V Vdss rating, supports 5.4A continuous drain current (exceeding the 6A requirement in most practical applications), and uses a compatible TO-220 package. The improved on-state resistance (1Ω) provides superior thermal performance. Verify gate drive voltage compatibility, as Vgs(th) is slightly elevated (4.5V vs. 4V).

Q: Why is the IRF734 listed as a secondary substitute despite higher voltage rating?

A: While the IRF734 offers 450V rating, it delivers only 4.9A continuous drain current, falling short of the original 6A specification. Additionally, RoHS non-compliance may conflict with supply chain or regulatory requirements. The significantly higher gate charge (45nC vs. 20nC) may require gate drive circuit redesign. Use the IRF734 only in applications where current requirements are below 5A and compliance status is not a constraint.

Q: Are TO-220-3 and TO-220AB packages mechanically interchangeable?

A: TO-220-3 and TO-220AB are both three-lead Through Hole packages with identical pin spacing and thermal interface characteristics. They are mechanically and thermally interchangeable on standard PCB footprints. Verify lead geometry and mounting hole alignment with your specific PCB design.

Q: What is the impact of gate charge differences on circuit performance?

A: Gate charge (Qg) affects switching speed and gate drive power requirements. The FQP6N40CF has 20nC gate charge, while the STP7NK40Z has 26nC and the IRF734 has 45nC. Higher gate charge requires longer switching times and increased gate drive current. For most applications, the STP7NK40Z's 26nC increase is negligible. The IRF734's 45nC charge may require gate drive circuit optimization.

Q: Does the STP7NK40Z's lower input capacitance (535pF vs. 625pF) affect design compatibility?

A: Lower input capacitance (Ciss) in the STP7NK40Z improves switching performance and reduces gate drive power dissipation. This is a beneficial characteristic that does not compromise design compatibility. It may improve overall circuit efficiency.

Q: Which substitute part should be selected for new designs?

A: The STP7NK40Z is the recommended choice for new designs. It maintains Active product status, ROHS3 compliance, and superior electrical performance characteristics. The FQP6N40CF's obsolete status makes the STP7NK40Z the appropriate long-term solution for design continuity and supply chain reliability.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message