STP17NK40Z Equivalent & Substitute Parts

Part Overview

The STP17NK40Z is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 400V drain-to-source voltage with 15A continuous drain current at 25°C. This device is packaged in TO-220AB through-hole configuration and is part of the SuperMESH™ series. The STP17NK40Z is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement continuity. Substitute parts must maintain electrical compatibility within the specified parameter ranges while accommodating the through-hole TO-220 package family.

Substiute Parts

STP17NK40Z

STMicroelectronicsIn Stock: 2112STP17NK40Z Datasheet

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FDP19N40

onsemiIn Stock: 22865FDP19N40 Datasheet

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FQP17N40

onsemiIn Stock: 6274FQP17N40 Datasheet

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SIHP18N50C-E3

Vishay SiliconixIn Stock: 4723SIHP18N50C-E3 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the STP17NK40Z is determined by the following criteria:

Mandatory Compatibility Parameters:

• FET Type: N-Channel
• Technology: MOSFET (Metal Oxide)
• Mounting Type: Through Hole
• Package Family: TO-220 variants (TO-220-3, TO-220AB)
• Drain to Source Voltage (Vdss): 400V or higher
• Operating Temperature Range: -55°C to 150°C minimum
• RoHS3 Compliance and REACH Unaffected status

Performance Parameters for Substitution:

• Continuous Drain Current (Id): Equal to or greater than 15A
• Power Dissipation: Equal to or greater than 150W
• Rds On (Max): Equal to or less than 250mOhm at specified conditions
• Gate Charge (Qg): Electrical characteristic for switching performance
• Vgs(th) and Input Capacitance: Secondary parameters affecting circuit behavior

The three substitute parts listed below meet these criteria with variations in current rating, power dissipation, and voltage rating that maintain or exceed the STP17NK40Z specifications.

Parameter Comparison

Engineering Selection Recommendations

FQP17N40 (onsemi QFET®)

The FQP17N40 is an active product with electrical parameters closely aligned to the STP17NK40Z. It maintains the 400V Vdss rating and provides 16A continuous drain current, exceeding the original 15A specification. Power dissipation is rated at 170W, providing 20W additional margin over the STP17NK40Z. The Rds On specification of 270mOhm at 8A, 10V is marginally higher than the original part. This substitute is suitable for direct replacement in applications where the slightly increased on-resistance is acceptable. RoHS3 compliance and active product status ensure long-term availability and regulatory alignment.

FDP19N40 (onsemi UniFET™)

The FDP19N40 offers the highest current rating at 19A continuous drain current with 215W power dissipation, providing significant performance headroom. The 400V Vdss rating matches the original specification. Notably, the Rds On is 240mOhm at 9.5A, 10V, which is lower than the STP17NK40Z, resulting in reduced conduction losses. Gate charge is reduced to 40nC, improving switching efficiency. However, this part is classified as obsolete, which may impact long-term procurement. RoHS3 compliance is maintained.

SIHP18N50C-E3 (Vishay Siliconix)

The SIHP18N50C-E3 provides the highest voltage rating at 500V Vdss, offering enhanced voltage margin for applications with transient overvoltage conditions. Continuous drain current is rated at 18A with 223W power dissipation. The Rds On specification of 270mOhm at 10A, 10V is comparable to the original part. Gate charge is 76nC, slightly higher than the STP17NK40Z. This part is active and RoHS3 compliant, ensuring availability. The elevated voltage rating introduces higher input capacitance (2942pF), which may affect switching characteristics in high-frequency applications.

Recommendation Summary:

For applications requiring direct electrical equivalence with active product status, the FQP17N40 is the primary selection. For applications benefiting from reduced conduction losses and higher current capability, the FDP19N40 is suitable despite obsolete status. For applications requiring enhanced voltage margin, the SIHP18N50C-E3 accommodates higher transient voltages at the cost of increased capacitance.

Frequently Asked Questions (FAQ)

Q: Can the FQP17N40 be used as a direct replacement for the STP17NK40Z?

A: Yes. The FQP17N40 maintains the same 400V Vdss rating, exceeds the 15A current requirement with 16A capability, and is packaged in TO-220-3. The Rds On is marginally higher at 270mOhm versus 250mOhm, resulting in slightly increased conduction losses. Pin configuration and thermal characteristics are compatible with the original TO-220 footprint.

Q: What is the primary advantage of the FDP19N40 over the STP17NK40Z?

A: The FDP19N40 provides 19A continuous drain current and 215W power dissipation, exceeding the original 15A and 150W ratings. Additionally, the Rds On is lower at 240mOhm, reducing conduction losses. Gate charge is reduced to 40nC, improving switching speed. These characteristics make it suitable for applications requiring higher current handling or improved efficiency.

Q: Why does the SIHP18N50C-E3 have a higher voltage rating?

A: The SIHP18N50C-E3 is rated for 500V Vdss compared to the STP17NK40Z at 400V. This higher voltage rating provides additional margin for transient overvoltage protection in applications subject to voltage spikes or switching transients. The trade-off is increased input capacitance (2942pF versus 1900pF), which may affect switching performance in high-frequency circuits.

Q: Are all substitute parts RoHS3 compliant?

A: Yes. All three substitute parts—FQP17N40, FDP19N40, and SIHP18N50C-E3—are RoHS3 compliant and REACH unaffected, meeting current environmental and regulatory requirements.

Q: What is the difference between TO-220-3 and TO-220AB packaging?

A: Both TO-220-3 and TO-220AB are through-hole packages with identical pin configurations and thermal characteristics. TO-220-3 is the standard designation for three-lead TO-220 packages. TO-220AB is an alternative designation used by some manufacturers. All substitute parts are compatible with the original TO-220 footprint.

Q: Which substitute part has the lowest on-resistance?

A: The FDP19N40 has the lowest Rds On at 240mOhm at 9.5A, 10V, compared to 250mOhm for the STP17NK40Z and 270mOhm for both the FQP17N40 and SIHP18N50C-E3. Lower on-resistance reduces conduction losses and heat generation.

Q: Is the FQP17N40 an active product?

A: Yes. The FQP17N40 is classified as active, ensuring ongoing availability and manufacturer support. The STP17NK40Z and FDP19N40 are both obsolete, which may limit future procurement options.

Q: How does gate charge affect circuit performance?

A: Gate charge (Qg) determines the energy required to switch the MOSFET on and off. Lower gate charge reduces switching losses and allows faster switching transitions. The FDP19N40 has the lowest gate charge at 40nC, while the SIHP18N50C-E3 has the highest at 76nC. This parameter is critical in high-frequency switching applications.

Q: Can these parts be used interchangeably in all applications?

A: Substitution depends on application-specific requirements. All three parts meet the mandatory electrical and mechanical criteria for the STP17NK40Z. However, differences in current rating, power dissipation, voltage rating, and gate charge may affect performance in specific circuits. Circuit validation is necessary to confirm suitability for each application.