IRFP450B N-Channel 500V 14A MOSFET Equivalent & Substitute Parts

Part Overview

The IRFP450B is an N-Channel metal oxide semiconductor field-effect transistor (MOSFET) manufactured by onsemi, rated for 500V drain-to-source voltage and 14A continuous drain current at 25°C. The device is housed in a TO-3P through-hole package and dissipates up to 205W at the case temperature. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility across voltage ratings, current handling, power dissipation, and thermal operating ranges while accommodating package variations.

Substiute Parts

IRFP450B

onsemiIn Stock: 1960IRFP450B Datasheet

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FDA16N50-F109

Fairchild SemiconductorIn Stock: 1183FDA16N50-F109 Datasheet

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STW20NK50Z

STMicroelectronicsIn Stock: 7836STW20NK50Z Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the IRFP450B are selected based on strict electrical and mechanical compatibility criteria. All substitute devices must meet or exceed the following core parameters:

• Drain to Source Voltage (Vdss): Minimum 500V to maintain voltage rating equivalence
• Continuous Drain Current (Id): Minimum 14A at 25°C to support the original current specification
• Power Dissipation (Max): Minimum 190W to ensure thermal handling capability
• Operating Temperature Range: Support -55°C to 150°C junction temperature range
• FET Type: N-Channel metal oxide semiconductor technology
• Mounting Type: Through-hole configuration for PCB compatibility

The FDA16N50-F109 and STW20NK50Z both satisfy these electrical requirements. Package variations (TO-3PN and TO-247-3 respectively) are acceptable substitutes provided the physical footprint accommodates the alternative package geometry in the target application.

Parameter Comparison

Engineering Selection Recommendations

FDA16N50-F109 (Fairchild Semiconductor)

The FDA16N50-F109 is an active product offering electrical specifications that directly align with the IRFP450B. It provides 16.5A continuous drain current and 205W power dissipation, matching the thermal envelope of the original part. The TO-3PN package is mechanically compatible with TO-3P footprints. Gate charge is significantly reduced (45 nC versus 113 nC), resulting in lower switching losses and improved efficiency. Input capacitance is also lower (1945 pF versus 3800 pF), reducing gate drive requirements. This device is suitable for direct substitution in applications where package compatibility can be accommodated.

STW20NK50Z (STMicroelectronics)

The STW20NK50Z is an active product from the SuperMESH™ series, delivering 17A continuous drain current and superior on-resistance performance (270 mOhm versus 390 mOhm). Power dissipation is rated at 190W, slightly below the original specification but sufficient for most applications operating within the 14A design envelope. The TO-247-3 package differs from the TO-3P, requiring PCB layout modification. Gate charge (119 nC) and input capacitance (2600 pF) are comparable to the original device. This device is suitable for applications where the TO-247-3 package footprint can be accommodated and where improved on-resistance performance is beneficial.

Both substitute parts maintain the 500V voltage rating, -55°C to 150°C operating temperature range, and N-Channel MOSFET technology required for functional equivalence. Product status is active for both alternatives, ensuring long-term availability and supply chain continuity.

Frequently Asked Questions (FAQ)

Q: Can the FDA16N50-F109 be used as a direct replacement for the IRFP450B without PCB modifications?

A: The FDA16N50-F109 uses a TO-3PN package, which is mechanically compatible with the TO-3P footprint of the IRFP450B. Pin configuration and lead spacing are equivalent, allowing direct substitution on existing PCBs designed for the original part.

Q: What are the advantages of the STW20NK50Z over the IRFP450B?

A: The STW20NK50Z offers lower on-resistance (270 mOhm versus 390 mOhm), reducing conduction losses and heat generation. Higher continuous drain current (17A versus 14A) provides additional design margin. However, the TO-247-3 package requires different PCB footprint and mounting hardware compared to the TO-3P.

Q: Are both substitute parts suitable for high-frequency switching applications?

A: The FDA16N50-F109 exhibits significantly lower gate charge (45 nC) and input capacitance (1945 pF), making it more suitable for high-frequency applications where switching losses must be minimized. The STW20NK50Z has gate charge and capacitance values closer to the original IRFP450B, making it appropriate for moderate-frequency applications.

Q: What is the impact of different package types on thermal management?

A: The TO-3P and TO-3PN packages (FDA16N50-F109) provide equivalent thermal performance. The TO-247-3 package (STW20NK50Z) has different thermal characteristics and mounting requirements. Thermal interface material and heatsink design may require adjustment when switching between package types.

Q: Are there compliance or certification differences between the substitute parts?

A: The FDA16N50-F109 and STW20NK50Z are both REACH Unaffected and classified as EAR99 for export control purposes, matching the compliance status of the IRFP450B. The STW20NK50Z carries RoHS3 compliance certification. All three devices have MSL rating of 1 (Unlimited), indicating no moisture sensitivity restrictions.

Q: Can the STW20NK50Z be used in applications designed for 14A continuous current?

A: Yes. The STW20NK50Z is rated for 17A continuous drain current, exceeding the 14A requirement of the original design. When operating at or below 14A, the device operates well within its specifications with improved thermal margin due to lower on-resistance.

Q: What considerations apply when selecting between the two substitute parts?

A: Selection depends on package compatibility with existing PCB design, thermal management requirements, and switching frequency. The FDA16N50-F109 offers direct package compatibility and lower switching losses. The STW20NK50Z provides superior on-resistance performance but requires PCB layout changes. Both maintain full electrical equivalence at the 500V, 14A operating point.