IRF730A N-Channel MOSFET 400V 5.5A Equivalent & Substitute Parts

Part Overview

The IRF730A is an N-Channel MOSFET manufactured by Vishay Siliconix, rated for 400V drain-to-source voltage with 5.5A continuous drain current at 25°C. The device is housed in a TO-220AB through-hole package and dissipates a maximum of 74W at the case temperature. The IRF730A is classified as obsolete, making equivalent and substitute parts necessary for new designs and ongoing production requirements. 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	5.5	A (Tc)
On-State Resistance (Rds On Max) @ Id, Vgs	1	Ohm @ 3.3A, 10V
Gate Threshold Voltage (Vgs(th) Max) @ Id	4.5	V @ 250µA
Gate Charge (Qg Max) @ Vgs	22	nC @ 10V
Maximum Gate Voltage (Vgs Max)	±30	V
Input Capacitance (Ciss Max) @ Vds	600	pF @ 25V
Power Dissipation (Max)	74	W (Tc)
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Through Hole	-
Package / Case	TO-220-3	-

Substitute Part Grouping Explanation

Substitution of the IRF730A is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Drain to Source Voltage (Vdss): Must equal 400V
Continuous Drain Current (Id) @ 25°C: Must be greater than or equal to 5.5A
Gate Threshold Voltage (Vgs(th)): Must be compatible with 4.5V maximum specification
Maximum Gate Voltage (Vgs Max): Must support ±30V
Operating Temperature Range: Must span -55°C to 150°C
Mounting Type: Must be Through Hole
Package / Case: Must be TO-220-3 or equivalent TO-220AB

Secondary Compatibility Parameters:

On-State Resistance (Rds On): Lower or equal values indicate improved performance
Gate Charge (Qg): Lower values reduce switching losses
Input Capacitance (Ciss): Lower values reduce gate drive requirements
Power Dissipation: Equal or higher ratings ensure thermal compatibility

All substitute parts listed maintain the 400V Vdss rating and support continuous drain currents at or above 5.5A. Packaging remains consistent with TO-220 through-hole configuration. Compliance certifications and product status are documented for each substitute to support procurement decisions.

Parameter Comparison

Parameter	IRF730A (Main)	IRF730APBF	FQP6N40CF	STP11NK40Z	STP7NK40Z
Manufacturer	Vishay Siliconix	Vishay Siliconix	onsemi	STMicroelectronics	STMicroelectronics
Vdss (V)	400	400	400	400	400
Id @ 25°C (A)	5.5	5.5	6	9	5.4
Rds On Max (Ohm)	1 @ 3.3A, 10V	1 @ 3.3A, 10V	1.1 @ 3A, 10V	0.55 @ 4.5A, 10V	1 @ 2.7A, 10V
Vgs(th) Max (V)	4.5 @ 250µA	4.5 @ 250µA	4 @ 250µA	4.5 @ 100µA	4.5 @ 50µA
Qg Max (nC)	22 @ 10V	22 @ 10V	20 @ 10V	32 @ 10V	26 @ 10V
Vgs Max (V)	±30	±30	±30	±30	±30
Ciss Max (pF)	600 @ 25V	600 @ 25V	625 @ 25V	930 @ 25V	535 @ 25V
Power Dissipation Max (W)	74	74	73	110	70
Operating Temperature (°C)	-55 to 150	-55 to 150	-55 to 150	-55 to 150	-55 to 150
Package / Case	TO-220-3	TO-220-3	TO-220-3	TO-220-3	TO-220-3
Product Status	Obsolete	Active	Obsolete	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

IRF730APBF (Vishay Siliconix)

The IRF730APBF is an identical electrical equivalent to the IRF730A with matching specifications across all key parameters: 400V Vdss, 5.5A continuous drain current, 1Ohm Rds On, and 74W power dissipation. The primary distinction is product status: IRF730APBF is active, whereas IRF730A is obsolete. IRF730APBF is ROHS3 compliant and supplied in tube packaging. This part is the direct replacement for the IRF730A and maintains full electrical and thermal compatibility. Current inventory is 3,400 units.

STP7NK40Z (STMicroelectronics)

The STP7NK40Z is an active substitute with 400V Vdss and 5.4A continuous drain current, providing near-equivalent current handling to the IRF730A at 5.5A. The device features 1Ohm Rds On at 2.7A and 70W power dissipation, both within acceptable margins of the main part. Gate charge is 26nC, slightly higher than the IRF730A at 22nC. Input capacitance is 535pF, lower than the main part, reducing gate drive requirements. STP7NK40Z is ROHS3 compliant, active product status, and supplied in tube packaging. Current inventory is 8,042 units.

STP11NK40Z (STMicroelectronics)

The STP11NK40Z is an active substitute with enhanced current capability: 400V Vdss and 9A continuous drain current, exceeding the IRF730A specification by 3.5A. On-state resistance is 0.55Ohm at 4.5A, significantly lower than the main part, resulting in reduced conduction losses. Power dissipation is 110W, 36W higher than the IRF730A, providing thermal margin. Gate charge is 32nC, higher than the main part. Input capacitance is 930pF, substantially higher, requiring increased gate drive capability. STP11NK40Z is ROHS3 compliant, active product status, and supplied in tube packaging. Current inventory is 20,200 units. This part is suitable for applications requiring higher current capacity and lower on-state losses.

FQP6N40CF (onsemi)

The FQP6N40CF is an obsolete substitute with 400V Vdss and 6A continuous drain current, marginally exceeding the IRF730A at 5.5A. On-state resistance is 1.1Ohm at 3A, slightly higher than the main part. Gate threshold voltage is 4V, lower than the IRF730A at 4.5V. Power dissipation is 73W, comparable to the main part. Gate charge is 20nC, lower than the IRF730A, reducing switching losses. FQP6N40CF is ROHS3 compliant but classified as obsolete. Current inventory is 1,829 units. This part is not recommended for new designs due to obsolete status.

Frequently Asked Questions (FAQ)

Q: Can the IRF730APBF directly replace the IRF730A in existing designs?

A: Yes. The IRF730APBF is electrically and mechanically identical to the IRF730A. All electrical parameters, including Vdss, Id, Rds On, gate charge, and power dissipation, are matched. Both devices use the TO-220-3 package. The primary difference is product status: IRF730APBF is active while IRF730A is obsolete. IRF730APBF is ROHS3 compliant, whereas IRF730A is not.

Q: What is the difference between the STP7NK40Z and STP11NK40Z?

A: Both devices are STMicroelectronics SuperMESH™ series MOSFETs with 400V Vdss. The STP7NK40Z provides 5.4A continuous drain current with 1Ohm Rds On and 70W power dissipation, closely matching the IRF730A. The STP11NK40Z provides 9A continuous drain current with 0.55Ohm Rds On and 110W power dissipation, offering higher current capacity and lower conduction losses. The STP11NK40Z has higher gate charge (32nC vs. 26nC) and input capacitance (930pF vs. 535pF), requiring more robust gate drive circuitry.

Q: Are all substitute parts ROHS3 compliant?

A: All substitute parts listed are ROHS3 compliant except the main part (IRF730A), which is RoHS non-compliant. The FQP6N40CF is also ROHS3 compliant but is classified as obsolete. IRF730APBF, STP7NK40Z, and STP11NK40Z are all ROHS3 compliant and active products.

Q: Can I use the STP11NK40Z as a drop-in replacement for the IRF730A?

A: The STP11NK40Z is mechanically compatible (TO-220-3 package) and electrically compatible (400V Vdss, ±30V Vgs Max, -55°C to 150°C operating range). However, the higher continuous drain current (9A vs. 5.5A), lower Rds On (0.55Ohm vs. 1Ohm), higher gate charge (32nC vs. 22nC), and higher input capacitance (930pF vs. 600pF) require verification of gate drive circuit capability. The STP11NK40Z is suitable for applications requiring higher current capacity and lower conduction losses.

Q: What is the significance of gate charge and input capacitance in substitution?

A: Gate charge (Qg) determines the total charge required to switch the MOSFET on or off. Input capacitance (Ciss) affects the gate drive impedance and switching speed. The IRF730A has 22nC gate charge and 600pF input capacitance. Substitute parts with lower values (STP7NK40Z: 26nC, 535pF; FQP6N40CF: 20nC, 625pF) require similar or less gate drive capability. The STP11NK40Z (32nC, 930pF) requires more robust gate drive circuitry. Verification of gate driver specifications is necessary when substituting parts with significantly different values.

Q: Why is the IRF730A obsolete?

A: The IRF730A is classified as obsolete by the manufacturer. The IRF730APBF, an active equivalent, is available as a direct replacement. Obsolete status indicates the manufacturer no longer produces the part, making substitution necessary for new production and long-term supply chain continuity.

Q: What packaging options are available for substitute parts?

A: All substitute parts are supplied in TO-220-3 through-hole packages, maintaining mechanical compatibility with the IRF730A. IRF730APBF, STP11NK40Z, and STP7NK40Z are supplied in tube packaging. FQP6N40CF packaging is not specified in the provided data.

Q: How do I select between the available substitutes?

A: Selection depends on application requirements. For direct replacement with active product status, use IRF730APBF. For applications requiring lower on-state losses and higher current capacity, use STP11NK40Z. For applications requiring minimal gate drive changes and active product status, use STP7NK40Z. Verify gate drive circuit compatibility, thermal management requirements, and compliance certifications for your specific application.

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