IRF730L N-Channel MOSFET 400V 5.5A Equivalent & Substitute Parts

Part Overview

The IRF730L is an N-Channel MOSFET rated for 400V drain-to-source voltage with 5.5A continuous drain current in an I2PAK (TO-262-3) through-hole package. This device is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production support. The IRF730L operates across a temperature range of -55°C to 150°C and is RoHS non-compliant.

Key Parameters

Parameter	Value	Unit
Drain-to-Source Voltage (Vdss)	400	V
Continuous Drain Current (Id) @ 25°C	5.5	A
On-State Resistance (Rds On) @ 3.3A, 10V	1	Ohm
Gate Threshold Voltage (Vgs(th)) @ 250µA	4	V
Gate Charge (Qg) @ 10V	22	nC
Input Capacitance (Ciss) @ 25V	600	pF
Maximum Gate Voltage (Vgs)	±20	V
Operating Temperature Range	-55 to 150	°C
Package Type	I2PAK (TO-262-3)	Through Hole

Substitute Part Grouping Explanation

Substitution of the IRF730L is determined by the following critical parameters:

Electrical Compatibility Requirements:

Drain-to-Source Voltage (Vdss) must equal or exceed 400V
Continuous Drain Current (Id) must meet or exceed 5.5A at 25°C
On-State Resistance (Rds On) characteristics must support equivalent switching performance
Gate Threshold Voltage (Vgs(th)) must be compatible with existing gate drive circuits
Operating temperature range must span -55°C to 150°C

Mechanical Compatibility Requirements:

Through-hole mounting type required
Package footprint must accommodate I2PAK or compatible TO-220 variants

The substitute parts listed below satisfy these electrical and mechanical criteria while offering improved availability and compliance status compared to the obsolete IRF730L.

Parameter Comparison

Parameter	IRF730L	FQP6N40CF	STP11NK40Z	STP7NK40Z	Unit
Manufacturer	Vishay Siliconix	onsemi	STMicroelectronics	STMicroelectronics	—
Vdss	400	400	400	400	V
Id @ 25°C	5.5	6	9	5.4	A
Rds On (Max)	1 @ 3.3A, 10V	1.1 @ 3A, 10V	0.55 @ 4.5A, 10V	1 @ 2.7A, 10V	Ohm
Vgs(th) (Max)	4 @ 250µA	4 @ 250µA	4.5 @ 100µA	4.5 @ 50µA	V
Qg (Max) @ 10V	22	20	32	26	nC
Ciss (Max) @ 25V	600	625	930	535	pF
Vgs (Max)	±20	±30	±30	±30	V
Operating Temperature	-55 to 150	-55 to 150	-55 to 150	-55 to 150	°C
Package	I2PAK (TO-262-3)	TO-220-3	TO-220-3	TO-220-3	—
Product Status	Obsolete	Obsolete	Active	Active	—
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	—

Engineering Selection Recommendations

STP7NK40Z (Primary Substitute)

The STP7NK40Z from STMicroelectronics is the closest electrical equivalent to the IRF730L. It provides 5.4A continuous drain current at 25°C, matching the IRF730L specification within 1.8% tolerance. The on-state resistance of 1Ohm at 2.7A and 10V gate voltage is equivalent to the IRF730L. This device is classified as active product status with ROHS3 compliance, ensuring long-term availability and regulatory alignment. The TO-220-3 package requires PCB layout modification from the original I2PAK footprint but maintains through-hole mounting compatibility.

STP11NK40Z (Higher Current Alternative)

The STP11NK40Z provides 9A continuous drain current with superior on-state resistance of 0.55Ohm at 4.5A and 10V, delivering enhanced performance headroom. This device is suitable for applications requiring higher current capacity or lower conduction losses. Active product status and ROHS3 compliance support long-term supply chain stability. Gate charge of 32nC is moderately higher than the IRF730L, requiring verification of gate drive circuit capability.

FQP6N40CF (Intermediate Option)

The FQP6N40CF from onsemi provides 6A continuous drain current with 1.1Ohm on-state resistance at 3A and 10V. This device offers a balance between the IRF730L and higher-current alternatives. Although classified as obsolete, it maintains ROHS3 compliance. The TO-220-3 package requires footprint modification.

Package Transition Consideration

All substitute parts use TO-220-3 through-hole packages, differing from the IRF730L I2PAK package. PCB layout redesign is required to accommodate the different pin spacing and thermal characteristics of the TO-220 package.

Frequently Asked Questions (FAQ)

Q: Can the STP7NK40Z directly replace the IRF730L without circuit modification?

A: The STP7NK40Z is electrically compatible with the IRF730L for applications operating within the specified current and voltage ranges. However, the package transition from I2PAK to TO-220-3 requires PCB layout modification. Gate drive circuits designed for the IRF730L operate within the STP7NK40Z gate voltage specifications (±30V maximum versus ±20V for IRF730L), eliminating gate drive circuit changes.

Q: What is the primary advantage of selecting STP11NK40Z over STP7NK40Z?

A: The STP11NK40Z provides 9A continuous drain current and 0.55Ohm on-state resistance, compared to 5.4A and 1Ohm for the STP7NK40Z. Applications requiring higher current capacity or lower conduction losses benefit from the STP11NK40Z. The trade-off is increased gate charge (32nC versus 26nC), which may require gate drive circuit evaluation.

Q: Are all substitute parts RoHS compliant?

A: Yes. The STP7NK40Z and STP11NK40Z are ROHS3 compliant. The FQP6N40CF is also ROHS3 compliant. The original IRF730L is RoHS non-compliant. Compliance with RoHS regulations is a key advantage of the substitute parts for new designs and regulated applications.

Q: What package considerations apply when transitioning from IRF730L to substitute parts?

A: The IRF730L uses an I2PAK (TO-262-3) package with long leads, while all substitute parts use standard TO-220-3 packages. The TO-220-3 package has different pin spacing and thermal characteristics. PCB layout redesign is required, including modifications to mounting hole positions, trace routing, and thermal management provisions. The TO-220 package typically offers improved thermal dissipation compared to I2PAK due to larger lead frame geometry.

Q: Can FQP6N40CF be used in applications currently using IRF730L?

A: The FQP6N40CF is electrically compatible with the IRF730L, providing 6A continuous drain current and 1.1Ohm on-state resistance. However, the FQP6N40CF is classified as obsolete, limiting long-term availability. For new designs, the active-status STP7NK40Z or STP11NK40Z are preferred alternatives.

Q: How do gate charge differences affect circuit performance?

A: The IRF730L has 22nC gate charge at 10V. The STP7NK40Z has 26nC, and the STP11NK40Z has 32nC. Higher gate charge requires longer switching times and increased gate drive current. Gate drive circuits must supply sufficient current to charge the gate within the required switching time window. Existing gate drive circuits designed for the IRF730L operate within acceptable parameters for the STP7NK40Z. The STP11NK40Z may require gate drive circuit evaluation if switching frequency or timing margins are critical.

Q: What is the thermal performance difference between I2PAK and TO-220 packages?

A: The TO-220 package provides superior thermal dissipation compared to I2PAK due to larger lead frame cross-section and improved heat spreading. Applications with thermal constraints may benefit from the TO-220 package transition. Thermal management design must account for the different package geometry and mounting configuration.

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