IRF730S MOSFET N-Channel 400V 5.5A Equivalent & Substitute Parts

Part Overview

The IRF730S is an N-Channel MOSFET manufactured by Vishay Siliconix, rated for 400V drain-to-source voltage with 5.5A continuous drain current. The device is housed in a Surface Mount TO-263 (D2PAK) package and is designed for high-voltage switching applications. The IRF730S is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement. Active alternatives with identical or superior electrical characteristics are available from both the original manufacturer and alternative suppliers.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	400	V
Current - Continuous Drain (Id) @ 25°C	5.5	A (Tc)
Rds On (Max) @ Id, Vgs	1	Ohm @ 3.3A, 10V
Vgs(th) (Max) @ Id	4	V @ 250µA
Gate Charge (Qg) (Max) @ Vgs	38	nC @ 10V
Power Dissipation (Max)	3.1 (Ta), 74 (Tc)	W
Operating Temperature	-55 to 150	°C (TJ)
Mounting Type	Surface Mount	—
Package / Case	TO-263-3, D2PAK	—

Substitute Part Grouping Explanation

Substitution of the IRF730S is determined by strict adherence to the following electrical and mechanical parameters:

Critical Matching Parameters:

Drain to Source Voltage (Vdss): 400V minimum
FET Type: N-Channel
Mounting Type: Surface Mount
Package / Case: TO-263 (D2PAK) compatible
Operating Temperature Range: -55°C to 150°C minimum

Functional Compatibility Parameters:

Current - Continuous Drain (Id): Equal to or greater than 5.5A
Rds On (Max): Equal to or less than 1 Ohm at specified conditions
Gate Charge (Qg): Comparable to 38 nC for switching performance
Vgs(th): Within ±20V gate voltage specification

Substitute parts are grouped into two categories:

Parametric Equivalent (IRF730SPBF): Identical electrical specifications with identical package. Differs only in product status (Active vs. Obsolete) and RoHS compliance level.
Manufacturer Recommended Substitute (STB11NK40ZT4): Superior electrical performance with higher continuous drain current (9A vs. 5.5A) and lower on-resistance (550mOhm vs. 1 Ohm). Maintains identical voltage rating and package compatibility. Represents an upgrade path for applications requiring enhanced thermal performance.

Parameter Comparison

Parameter	IRF730S	IRF730SPBF	STB11NK40ZT4
Manufacturer	Vishay Siliconix	Vishay Siliconix	STMicroelectronics
FET Type	N-Channel	N-Channel	N-Channel
Drain to Source Voltage (Vdss)	400V	400V	400V
Current - Continuous Drain (Id) @ 25°C	5.5A (Tc)	5.5A (Tc)	9A (Tc)
Rds On (Max) @ Id, Vgs	1 Ohm @ 3.3A, 10V	1 Ohm @ 3.3A, 10V	550 mOhm @ 4.5A, 10V
Vgs(th) (Max) @ Id	4V @ 250µA	4V @ 250µA	4.5V @ 100µA
Gate Charge (Qg) (Max) @ Vgs	38 nC @ 10V	38 nC @ 10V	32 nC @ 10V
Vgs (Max)	±20V	±20V	±30V
Input Capacitance (Ciss) (Max) @ Vds	700 pF @ 25V	700 pF @ 25V	930 pF @ 25V
Power Dissipation (Max)	3.1W (Ta), 74W (Tc)	3.1W (Ta), 74W (Tc)	110W (Tc)
Operating Temperature	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)
Mounting Type	Surface Mount	Surface Mount	Surface Mount
Package / Case	TO-263-3, D2PAK	TO-263-3, D2PAK	TO-263-3, D2PAK
Product Status	Obsolete	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For Direct Replacement (Pin-Compatible, Identical Specifications):

The IRF730SPBF is the direct parametric equivalent to the IRF730S. Both devices share identical electrical characteristics, voltage ratings, current ratings, and thermal specifications. The IRF730SPBF is classified as Active product status, ensuring long-term availability and supply chain continuity. The IRF730SPBF carries ROHS3 compliance certification, whereas the IRF730S is RoHS non-compliant. Selection of IRF730SPBF is appropriate for applications requiring exact electrical performance matching and regulatory compliance with modern environmental standards.

For Performance Enhancement (Higher Current and Lower On-Resistance):

The STB11NK40ZT4 from STMicroelectronics provides superior electrical performance while maintaining full voltage and package compatibility. The device delivers 9A continuous drain current compared to 5.5A, and features 550 mOhm on-resistance compared to 1 Ohm. Power dissipation capability increases to 110W (Tc) from 74W (Tc). The STB11NK40ZT4 is classified as Active product status with ROHS3 compliance. This device is suitable for applications where thermal margin improvement, higher current handling, or reduced switching losses are beneficial. The lower gate charge (32 nC vs. 38 nC) provides faster switching characteristics.

Both substitute parts maintain identical operating temperature range (-55°C to 150°C), identical package form factor (TO-263 D2PAK), and identical drain-to-source voltage rating (400V). Both are classified as REACH Unaffected and carry EAR99 ECCN designation.

Frequently Asked Questions (FAQ)

Q: Can the IRF730SPBF be used as a direct replacement for the IRF730S?

A: Yes. The IRF730SPBF is a parametric equivalent with identical electrical specifications, voltage ratings, current ratings, and thermal characteristics. Both devices are housed in the TO-263 (D2PAK) package with identical pinout. The primary differences are product status (Active vs. Obsolete) and RoHS compliance level (ROHS3 vs. non-compliant). Pin-for-pin substitution is valid.

Q: What are the advantages of using the STB11NK40ZT4 over the IRF730SPBF?

A: The STB11NK40ZT4 provides enhanced electrical performance: 63% higher continuous drain current (9A vs. 5.5A), 45% lower on-resistance (550 mOhm vs. 1 Ohm), and 49% higher power dissipation capability (110W vs. 74W at Tc). Gate charge is reduced by 16% (32 nC vs. 38 nC), enabling faster switching. These improvements reduce thermal stress and switching losses in high-current applications. The device maintains identical 400V voltage rating and TO-263 package compatibility.

Q: Are there any package compatibility concerns when substituting these parts?

A: No. All three devices (IRF730S, IRF730SPBF, and STB11NK40ZT4) use the TO-263-3 (D2PAK) package with identical pinout: Gate, Drain, and Source connections. PCB footprints are interchangeable. No layout modifications are required for substitution.

Q: What is the operating temperature range for these devices?

A: All three devices operate across the identical temperature range of -55°C to 150°C (junction temperature). Thermal performance differs due to power dissipation ratings, but temperature operating limits are equivalent.

Q: Are these devices RoHS compliant?

A: The IRF730S is RoHS non-compliant. Both the IRF730SPBF and STB11NK40ZT4 are ROHS3 compliant, meeting current environmental regulations. For applications requiring RoHS compliance, either the IRF730SPBF or STB11NK40ZT4 is required.

Q: What is the gate voltage specification for these MOSFETs?

A: The IRF730S and IRF730SPBF support ±20V maximum gate voltage. The STB11NK40ZT4 supports ±30V maximum gate voltage, providing additional gate drive margin. All devices have threshold voltage (Vgs(th)) specifications within 4V to 4.5V at specified drain current conditions.

Q: How do the gate charge specifications compare?

A: Gate charge (Qg) at 10V is 38 nC for both the IRF730S and IRF730SPBF, and 32 nC for the STB11NK40ZT4. Lower gate charge enables faster switching transitions and reduced driver power consumption. The STB11NK40ZT4 provides a 16% reduction in gate charge.

Q: What is the input capacitance difference between these devices?

A: Input capacitance (Ciss) at 25V is 700 pF for the IRF730S and IRF730SPBF, and 930 pF for the STB11NK40ZT4. The higher capacitance in the STB11NK40ZT4 is associated with its higher current rating and lower on-resistance. This affects gate drive circuit design but does not prevent substitution.

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