IRFU320 N-Channel MOSFET 400V 3.1A Equivalent & Substitute Parts

Part Overview

The IRFU320 is an N-Channel MOSFET manufactured by Vishay Siliconix, rated for 400V drain-to-source voltage with 3.1A continuous drain current. The device is packaged in a TO-251AA through-hole configuration and is designed for general-purpose switching applications requiring moderate power dissipation capability.

The IRFU320 is classified as obsolete, which necessitates identification of equivalent and substitute components for ongoing design support and procurement. Active alternatives with identical or superior electrical characteristics are available from multiple manufacturers, enabling seamless integration into existing designs or new production runs.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain-to-Source Voltage (Vdss)	400	V
Continuous Drain Current (Id) @ 25°C	3.1	A (Tc)
On-State Resistance (Rds On) @ Id, Vgs	1.8 @ 1.9A, 10V	Ohm
Gate Threshold Voltage (Vgs(th)) @ Id	4 @ 250µA	V
Gate Charge (Qg) @ Vgs	20 @ 10V	nC
Power Dissipation (Max)	2.5 (Ta), 42 (Tc)	W
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package	TO-251-3 Short Leads, IPak, TO-251AA	—

Substitute Part Grouping Explanation

Substitution of the IRFU320 is determined by the following critical electrical and mechanical parameters:

Voltage Rating: All substitute parts must maintain a minimum Vdss of 400V to ensure compatibility with the original design voltage specifications.

Current Rating: Substitute parts must support a continuous drain current (Id) equal to or greater than 3.1A at 25°C to handle the intended load without thermal stress.

On-State Resistance (Rds On): The maximum on-state resistance must not exceed the original specification to prevent excessive power dissipation and thermal runaway in the application circuit.

Gate Threshold Voltage (Vgs(th)): Substitute parts must operate within compatible gate drive voltage ranges to ensure proper switching behavior with existing gate driver circuits.

Package and Mounting: All substitutes utilize through-hole TO-251 family packaging (TO-251AA or TO-251A variants) to maintain mechanical compatibility with printed circuit board layouts.

Operating Temperature Range: Substitute parts must support the full operating temperature range of -55°C to 150°C (TJ) or equivalent to ensure reliability across all environmental conditions.

Product Status and Compliance: Active product status and RoHS3 compliance are preferred to ensure long-term availability and regulatory conformance.

Parameter Comparison

Parameter	IRFU320	IRFU320PBF	AOI5N40	STD5NK40Z-1
Manufacturer	Vishay Siliconix	Vishay Siliconix	Alpha & Omega Semiconductor Inc.	STMicroelectronics
Product Status	Obsolete	Active	Active	Active
FET Type	N-Channel	N-Channel	N-Channel	N-Channel
Vdss (V)	400	400	400	400
Id @ 25°C (A)	3.1	3.1	4.2	3.0
Rds On (Max) @ Id, Vgs (Ohm)	1.8 @ 1.9A, 10V	1.8 @ 1.9A, 10V	1.6 @ 1A, 10V	1.8 @ 1.5A, 10V
Vgs(th) (Max) @ Id (V)	4 @ 250µA	4 @ 250µA	4.5 @ 250µA	4.5 @ 50µA
Gate Charge (Qg) @ 10V (nC)	20	20	8.5	17
Vgs (Max) (±V)	±20	±20	±30	±30
Ciss (Max) @ 25V (pF)	350	350	400	305
Power Dissipation (Max) (W)	2.5 (Ta), 42 (Tc)	2.5 (Ta), 42 (Tc)	78 (Tc)	45 (Tc)
Operating Temperature (°C)	-55 to 150	-55 to 150	-50 to 150	-55 to 150
Package	TO-251-3 Short Leads, IPak, TO-251AA	TO-251-3 Short Leads, IPak, TO-251AA	TO-251-3 Stub Leads, IPak	TO-251-3 Short Leads, IPak, TO-251AA
RoHS Status	RoHS non-compliant	RoHS3 Compliant	RoHS3 Compliant	RoHS3 Compliant
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole

Engineering Selection Recommendations

IRFU320PBF (Vishay Siliconix): This is the direct parametric equivalent to the IRFU320, offering identical electrical specifications including Vdss, Id, Rds On, and gate charge characteristics. The primary distinction is product status: IRFU320PBF is active and RoHS3 compliant, whereas the original IRFU320 is obsolete and non-compliant. IRFU320PBF is the preferred first-choice substitute for direct replacement in existing designs. Packaging is identical (TO-251AA), ensuring mechanical compatibility without PCB layout modifications.

AOI5N40 (Alpha & Omega Semiconductor Inc.): This device exceeds the IRFU320 specifications in current rating (4.2A versus 3.1A) and power dissipation capability (78W versus 42W). The on-state resistance is lower (1.6 Ohm), providing improved efficiency. Gate charge is reduced (8.5 nC versus 20 nC), enabling faster switching. Maximum gate voltage rating is higher (±30V versus ±20V). The device operates across a slightly narrower temperature range (-50°C to 150°C versus -55°C to 150°C). Package variant is TO-251A with stub leads rather than short leads. AOI5N40 is suitable for applications requiring enhanced thermal performance or higher current capacity, with the caveat that PCB layout verification is necessary due to lead configuration differences.

STD5NK40Z-1 (STMicroelectronics): This device maintains the IRFU320 voltage rating (400V) and offers comparable current rating (3A versus 3.1A) and on-state resistance (1.8 Ohm). Gate charge is slightly lower (17 nC versus 20 nC), and maximum gate voltage is higher (±30V versus ±20V). Power dissipation capability is intermediate (45W versus 42W). Operating temperature range matches the original (-55°C to 150°C). Package is TO-251 (IPAK) with short leads, maintaining mechanical compatibility. STD5NK40Z-1 is a suitable substitute offering active product status and RoHS3 compliance with minimal design impact.

All three substitute parts are active products with RoHS3 compliance and REACH unaffected status, ensuring regulatory conformance and long-term procurement availability.

Frequently Asked Questions (FAQ)

Q: Can IRFU320PBF be used as a direct drop-in replacement for IRFU320?

A: Yes. IRFU320PBF is the parametric equivalent with identical electrical specifications and package configuration (TO-251AA). The only differences are product status (active versus obsolete) and RoHS compliance (RoHS3 versus non-compliant). No circuit modifications or PCB layout changes are required.

Q: What is the primary advantage of AOI5N40 over IRFU320?

A: AOI5N40 provides higher continuous drain current (4.2A versus 3.1A), lower on-state resistance (1.6 Ohm versus 1.8 Ohm), and significantly higher power dissipation capability (78W versus 42W). These characteristics reduce thermal stress and improve efficiency in high-current applications. Gate charge is also lower (8.5 nC), enabling faster switching transitions.

Q: Are there package compatibility concerns when substituting with AOI5N40?

A: AOI5N40 uses TO-251A packaging with stub leads, whereas IRFU320 uses TO-251AA with short leads. While both are TO-251 family devices, the lead configuration differs. PCB layout verification is necessary to confirm mechanical fit and solder joint integrity. Electrical compatibility is not affected.

Q: Does STD5NK40Z-1 require any design modifications?

A: No design modifications are required. STD5NK40Z-1 maintains the 400V voltage rating, comparable current rating (3A), and identical on-state resistance (1.8 Ohm). Package is TO-251 (IPAK) with short leads, matching the original IRFU320 mechanical configuration. Operating temperature range is identical (-55°C to 150°C).

Q: Which substitute part is recommended for new designs?

A: IRFU320PBF is recommended for new designs requiring direct compatibility with existing IRFU320 specifications. For applications where enhanced thermal performance or higher current capacity is beneficial, AOI5N40 or STD5NK40Z-1 are suitable alternatives. All three parts are active products with RoHS3 compliance.

Q: What is the significance of gate charge differences among the substitute parts?

A: Gate charge (Qg) determines the energy required to switch the MOSFET on and off. Lower gate charge (AOI5N40 at 8.5 nC) enables faster switching and reduces gate driver power consumption. Higher gate charge (IRFU320 at 20 nC) requires more energy but may be compatible with lower-power gate driver circuits. Selection depends on gate driver capability and switching frequency requirements.

Q: Are all substitute parts suitable for the full -55°C to 150°C operating temperature range?

A: IRFU320PBF and STD5NK40Z-1 support the full -55°C to 150°C range. AOI5N40 operates from -50°C to 150°C, which is acceptable for most applications but does not extend to the lower temperature limit of the original IRFU320. Verify application requirements before selecting AOI5N40 for extreme low-temperature environments.

Q: What is the impact of different Vgs(th) values on circuit operation?

A: Gate threshold voltage (Vgs(th)) determines the minimum gate voltage required to initiate conduction. IRFU320 and IRFU320PBF specify 4V @ 250µA, while AOI5N40 and STD5NK40Z-1 specify 4.5V @ 250µA or 4.5V @ 50µA. These differences are within typical gate driver output ranges and do not require circuit modifications. Verify gate driver output voltage compatibility with the selected device.

Q: Can substitute parts be mixed in the same circuit board?

A: Mixing substitute parts on the same PCB is not recommended unless the circuit design explicitly accounts for parameter variations. Consistent device selection ensures uniform switching characteristics, thermal behavior, and reliability. If multiple devices are required, select a single substitute part for all positions.

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