IRFR420 N-Channel MOSFET 500V 2.4A DPAK Equivalent & Substitute Parts

Part Overview

The IRFR420 is an N-Channel Metal Oxide Semiconductor Field Effect Transistor (MOSFET) rated for 500V drain-to-source voltage with a continuous drain current of 2.4A at 25°C. The device is housed in a DPAK (TO-252-3) surface mount package and is designed for general-purpose switching applications requiring high voltage capability in a compact form factor.

The IRFR420 is classified as obsolete. Locating equivalent or substitute components is necessary to support ongoing production requirements, field repairs, and design continuity. Active alternatives with identical or compatible electrical and mechanical specifications are available from the same manufacturer and qualified alternative suppliers.

Key Parameters

Parameter	Value	Unit
Drain to Source Voltage (Vdss)	500	V
Continuous Drain Current (Id) @ 25°C	2.4	A (Tc)
Drive Voltage (Max Rds On)	10	V
Rds On (Max) @ Id, Vgs	3	Ohm @ 1.4A, 10V
Gate Threshold Voltage Vgs(th) (Max) @ Id	4	V @ 250µA
Gate Charge (Qg) (Max) @ Vgs	19	nC @ 10V
Maximum Gate Voltage (Vgs)	±20	V
Input Capacitance (Ciss) (Max) @ Vds	360	pF @ 25V
Power Dissipation (Max)	2.5 (Ta), 42 (Tc)	W
Operating Temperature Range	-55 to 150	°C (TJ)
Mounting Type	Surface Mount
Package / Case	TO-252-3, DPAK (2 Leads + Tab), SC-63
Moisture Sensitivity Level (MSL)	1 (Unlimited)

Substitute Part Grouping Explanation

Substitution of the IRFR420 is determined by strict equivalence across the following critical parameters:

Primary Equivalence Criteria:

Drain to Source Voltage (Vdss): 500V minimum
Continuous Drain Current (Id): 2.4A or greater at 25°C
Drive Voltage: 10V gate drive capability
On-State Resistance (Rds On): 3 Ohm or lower at specified conditions
Gate Threshold Voltage (Vgs(th)): 4V or lower
Package Type: DPAK (TO-252-3) surface mount
Operating Temperature Range: -55°C to 150°C minimum

Substitute Categories:

Category 1: Direct Parametric Equivalents Parts that maintain identical electrical specifications and active product status. These components are pin-compatible and functionally interchangeable without circuit modification.

Category 2: Qualified Alternatives Parts that meet or exceed the primary electrical specifications with minor parameter variations within acceptable engineering tolerances. These components are functionally compatible but may exhibit different performance characteristics in specific applications.

Parameter Comparison

Parameter	IRFR420 (Obsolete)	IRFR420PBF (Active)	STD3NK50ZT4 (Active)
Manufacturer	Vishay Siliconix	Vishay Siliconix	STMicroelectronics
Product Status	Obsolete	Active	Active
Drain to Source Voltage (Vdss)	500V	500V	500V
Continuous Drain Current (Id) @ 25°C	2.4A (Tc)	2.4A (Tc)	2.3A (Tc)
Drive Voltage (Max Rds On)	10V	10V	10V
Rds On (Max) @ Id, Vgs	3Ohm @ 1.4A, 10V	3Ohm @ 1.4A, 10V	3.3Ohm @ 1.15A, 10V
Gate Threshold Voltage Vgs(th) (Max) @ Id	4V @ 250µA	4V @ 250µA	4.5V @ 50µA
Gate Charge (Qg) (Max) @ Vgs	19nC @ 10V	19nC @ 10V	15nC @ 10V
Maximum Gate Voltage (Vgs)	±20V	±20V	±30V
Input Capacitance (Ciss) (Max) @ Vds	360pF @ 25V	360pF @ 25V	280pF @ 25V
Power Dissipation (Max)	2.5W (Ta), 42W (Tc)	2.5W (Ta), 42W (Tc)	45W (Tc)
Operating Temperature Range	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)	-55°C to 150°C (TJ)
Package / Case	TO-252-3, DPAK	TO-252-3, DPAK	TO-252-3, DPAK
Mounting Type	Surface Mount	Surface Mount	Surface Mount
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant
Moisture Sensitivity Level (MSL)	1 (Unlimited)	1 (Unlimited)	1 (Unlimited)

Engineering Selection Recommendations

IRFR420PBF (Vishay Siliconix)

The IRFR420PBF is the primary substitute for the obsolete IRFR420. This component is manufactured by the same supplier and maintains identical electrical specifications across all critical parameters: 500V Vdss, 2.4A continuous drain current, 3 Ohm Rds On, and 19 nC gate charge. The IRFR420PBF is classified as an active product with ROHS3 compliance and REACH affected status, making it suitable for new designs and production environments with regulatory requirements. The component is available in tube packaging and maintains the same DPAK surface mount form factor. Inventory availability is significantly higher than the obsolete IRFR420, supporting both immediate and sustained production needs.

STD3NK50ZT4 (STMicroelectronics)

The STD3NK50ZT4 is a qualified alternative from STMicroelectronics rated for 500V Vdss with 2.3A continuous drain current. This component meets the primary voltage and current specifications with minor variations in on-state resistance (3.3 Ohm versus 3 Ohm) and gate threshold voltage (4.5V versus 4V). The STD3NK50ZT4 features lower gate charge (15 nC versus 19 nC) and reduced input capacitance (280 pF versus 360 pF), resulting in improved switching performance and reduced gate drive requirements. Power dissipation capability is enhanced at 45W (Tc) compared to 42W (Tc) for the IRFR420. The device is ROHS3 compliant, REACH unaffected, and available in cut tape and digi-reel packaging. The STD3NK50ZT4 is suitable for applications where improved switching characteristics and thermal performance provide design advantages.

Product Status Consideration

Both substitute parts are classified as active products, ensuring long-term availability and continued manufacturing support. The IRFR420PBF is the direct replacement for obsolete inventory management and design continuity. The STD3NK50ZT4 is appropriate for new designs requiring enhanced performance characteristics within the same voltage and current class.

Frequently Asked Questions (FAQ)

Q: Can the IRFR420PBF be used as a direct replacement for the IRFR420?

A: Yes. The IRFR420PBF is electrically and mechanically identical to the IRFR420 across all specified parameters. Both components feature 500V Vdss, 2.4A continuous drain current, 3 Ohm Rds On, and DPAK surface mount packaging. The IRFR420PBF is an active product, whereas the IRFR420 is obsolete. No circuit modifications are required for substitution.

Q: What are the key differences between the IRFR420PBF and STD3NK50ZT4?

A: The IRFR420PBF and STD3NK50ZT4 both meet the 500V voltage and 2.3-2.4A current specifications. The STD3NK50ZT4 exhibits slightly higher on-state resistance (3.3 Ohm versus 3 Ohm), higher gate threshold voltage (4.5V versus 4V), lower gate charge (15 nC versus 19 nC), and lower input capacitance (280 pF versus 360 pF). The STD3NK50ZT4 provides enhanced thermal performance at 45W (Tc) versus 42W (Tc). These differences result in improved switching speed and reduced gate drive power for the STD3NK50ZT4, with a minor trade-off in on-state conduction losses.

Q: Are both substitute parts RoHS compliant?

A: Yes. Both the IRFR420PBF and STD3NK50ZT4 are ROHS3 compliant. The original IRFR420 is RoHS non-compliant. For applications requiring RoHS compliance, either substitute part is appropriate.

Q: What is the moisture sensitivity level for these components?

A: All three components—IRFR420, IRFR420PBF, and STD3NK50ZT4—are classified as MSL 1 (Unlimited). This indicates unlimited shelf life without moisture absorption concerns, simplifying storage and handling requirements.

Q: Can the STD3NK50ZT4 be used in applications designed for the IRFR420?

A: The STD3NK50ZT4 is functionally compatible with applications designed for the IRFR420 within the specified voltage and current operating ranges. The component meets the primary electrical specifications and maintains the same DPAK package form factor. Minor parameter variations in on-state resistance, gate threshold voltage, and gate charge may affect circuit performance in applications with tight design margins or specific switching speed requirements. Circuit-level evaluation is appropriate for applications with critical timing or thermal constraints.

Q: What packaging options are available for each substitute part?

A: The IRFR420PBF is available in tube packaging. The STD3NK50ZT4 is available in cut tape (CT) and digi-reel packaging. Both components are surface mount DPAK devices suitable for automated assembly processes.

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

A: For new designs requiring direct electrical equivalence to the IRFR420 specification, the IRFR420PBF is the appropriate selection. For new designs where improved switching performance and thermal capability provide design advantages, the STD3NK50ZT4 is suitable. Both components are active products with long-term availability and regulatory compliance.

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