STF17NF25 N-Channel MOSFET 250V 17A Equivalent & Substitute Parts

Part Overview

The STF17NF25 is an N-Channel MOSFET manufactured by STMicroelectronics in the STripFET™ II series, rated for 250V drain-to-source voltage and 17A continuous drain current at 25°C. The device is packaged in a Through Hole TO-220FP configuration with a maximum power dissipation of 25W. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing design support and procurement.

Substiute Parts

STF17NF25

STMicroelectronicsIn Stock: 66922STF17NF25 Datasheet

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FDPF33N25T

onsemiIn Stock: 1744FDPF33N25T Datasheet

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FQPF27N25

onsemiIn Stock: 31954FQPF27N25 Datasheet

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IRFI644GPBF

Vishay SiliconixIn Stock: 1719IRFI644GPBF Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the STF17NF25 is determined by the following critical parameters:

Mandatory Matching Parameters:

• FET Type: N-Channel
• Drain to Source Voltage (Vdss): 250V minimum
• Mounting Type: Through Hole
• Package / Case: TO-220-3 compatible
• Operating Temperature Range: -55°C to 150°C (TJ)

Performance Compatibility Parameters:

• Current - Continuous Drain (Id) @ 25°C: Equal to or greater than 17A
• Rds On (Max): Equal to or lower than 165mOhm (lower is acceptable for improved performance)
• Gate Charge (Qg): Lower values preferred for faster switching
• Power Dissipation (Max): Equal to or greater than 25W

The three substitute parts listed below meet all mandatory matching parameters and provide equivalent or superior electrical performance characteristics within the specified operating envelope.

Parameter Comparison

Engineering Selection Recommendations

FDPF33N25T (onsemi UniFET™ Series)

The FDPF33N25T is the primary substitute for the STF17NF25. This part exceeds the original specifications with 33A continuous drain current (versus 17A) and lower on-resistance of 94mOhm (versus 165mOhm). The higher power dissipation rating of 37W provides additional thermal margin. The FDPF33N25T is in active product status with full ROHS3 compliance and REACH unaffected designation. This part is suitable for direct replacement in applications where the higher current rating and improved performance characteristics are beneficial or neutral.

FQPF27N25 (onsemi QFET® Series)

The FQPF27N25 provides an alternative with 14A continuous drain current and 110mOhm on-resistance. This part is rated for 55W maximum power dissipation, offering superior thermal performance. The FQPF27N25 is in active product status with ROHS3 compliance. This substitute is appropriate for applications where the slightly lower current rating is acceptable and the enhanced power dissipation capability is advantageous.

IRFI644GPBF (Vishay Siliconix)

The IRFI644GPBF is a lower-performance substitute with 7.9A continuous drain current and 280mOhm on-resistance. This part is suitable only for applications where the original 17A current requirement can be reduced or where the circuit design accommodates the higher on-resistance. The IRFI644GPBF is in active product status with ROHS3 compliance and MSL 1 rating. The isolated tab package variant may require mechanical design consideration.

All three substitute parts maintain the mandatory electrical and thermal operating envelope of the STF17NF25 and are ROHS3 compliant with REACH unaffected status.

Frequently Asked Questions (FAQ)

Q: Can the FDPF33N25T directly replace the STF17NF25 in all applications?

A: The FDPF33N25T meets all mandatory substitution criteria: identical Vdss (250V), compatible TO-220-3 package, matching operating temperature range (-55°C to 150°C), and superior electrical performance (33A versus 17A, 94mOhm versus 165mOhm). Direct replacement is supported from an electrical and mechanical standpoint. Circuit-level validation is required to confirm performance in the specific application context.

Q: What is the key difference between the FQPF27N25 and FDPF33N25T?

A: Both parts share identical Vdss (250V) and package specifications. The primary differences are continuous drain current (14A versus 33A) and on-resistance (110mOhm versus 94mOhm). The FQPF27N25 offers higher power dissipation capability (55W versus 37W), making it suitable for applications with lower current requirements but higher switching losses.

Q: Why is the IRFI644GPBF listed as a substitute if it has only 7.9A rating?

A: The IRFI644GPBF meets all mandatory substitution parameters: N-Channel FET, 250V Vdss, TO-220-3 package, and matching operating temperature range. However, the significantly lower continuous drain current (7.9A versus 17A) and higher on-resistance (280mOhm versus 165mOhm) restrict its use to applications where these reduced specifications are acceptable. This part is included for completeness in the substitute list but is not recommended as a primary replacement.

Q: Are there package compatibility concerns between TO-220FP and TO-220F-3?

A: The STF17NF25 uses TO-220FP packaging, while FDPF33N25T and FQPF27N25 use TO-220F-3 packaging. Both are Through Hole TO-220-3 compatible packages with identical pin configurations and mechanical footprints. The IRFI644GPBF uses TO-220-3 with an isolated tab variant. All three substitutes are mechanically compatible with the original PCB layout.

Q: What is the significance of the obsolete product status for the STF17NF25?

A: The obsolete status indicates that STMicroelectronics has discontinued manufacturing and support for the STF17NF25. All three substitute parts are in active product status, ensuring long-term availability, ongoing manufacturer support, and continued compliance with current regulatory standards. Active status parts are recommended for new designs and ongoing production.

Q: Do all substitute parts maintain ROHS3 compliance?

A: Yes. The STF17NF25 and all three substitute parts (FDPF33N25T, FQPF27N25, IRFI644GPBF) are ROHS3 compliant. All parts are REACH unaffected. This ensures regulatory compliance across all substitution options.

Q: How does gate charge affect substitution suitability?

A: Gate charge (Qg) determines the energy required to switch the FET and influences switching speed. The STF17NF25 has 29.5nC gate charge. The FDPF33N25T (48nC), FQPF27N25 (65nC), and IRFI644GPBF (68nC) all have higher gate charge values. Higher gate charge results in slower switching transitions and increased driver power requirements. Circuit designs with current-limited gate drivers may require adjustment when substituting to parts with higher gate charge.