IRFPS35N50LPBF Equivalent & Substitute Parts

Part Overview

The IRFPS35N50LPBF is an N-Channel 500V 34A MOSFET manufactured by Vishay Siliconix in the SUPER-247™ (TO-274AA) package. This device is rated for 450W continuous power dissipation and operates across the temperature range of -55°C to 150°C. The part is classified as obsolete, making identification of functionally equivalent alternatives necessary for ongoing design support and procurement continuity. Substitute parts must maintain compatibility with the 500V drain-source voltage rating, support continuous drain current of 34A or greater, and operate within the specified temperature range while maintaining similar on-resistance characteristics.

Key Parameters

Parameter	Value	Unit
FET Type	N-Channel	—
Drain to Source Voltage (Vdss)	500	V
Current - Continuous Drain (Id) @ 25°C	34	A (Tc)
Rds On (Max) @ Id, Vgs	145	mOhm @ 20A, 10V
Power Dissipation (Max)	450	W (Tc)
Operating Temperature	-55 to 150	°C (TJ)
Mounting Type	Through Hole	—
Package / Case	TO-274AA	—
RoHS Status	ROHS3 Compliant	—

Substitute Part Grouping Explanation

Substitution of the IRFPS35N50LPBF is determined by the following critical electrical and mechanical parameters:

Primary Substitution Criteria:

Drain-Source Voltage (Vdss): Minimum 500V (equal or higher rating acceptable)
Continuous Drain Current (Id): Minimum 34A at 25°C (equal or higher rating acceptable)
On-Resistance (Rds On): Maximum 145mOhm at specified gate voltage (lower values acceptable)
Power Dissipation: Minimum 450W (higher ratings acceptable)
Operating Temperature Range: -55°C to 150°C (must encompass or match)
Mounting Type: Through Hole (required for PCB compatibility)
Technology: N-Channel MOSFET (Metal Oxide)

Package Compatibility: The original SUPER-247™ (TO-274AA) package may be substituted with equivalent through-hole packages including TO-247-3, TO-247AD, ISOPLUS247™, and PLUS247™-3, provided mechanical fit and thermal characteristics remain acceptable for the application.

Compliance Requirements: All substitute parts must maintain ROHS3 compliance and REACH unaffected status to ensure regulatory alignment with the original component.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Vdss (V)	Id @ 25°C (A)	Rds On (mOhm)	Power Dissipation (W)	Package / Case	Product Status
IRFPS35N50LPBF	Vishay Siliconix	500	34	145 @ 20A, 10V	450	TO-274AA	Obsolete
IPW50R140CPFKSA1	Infineon Technologies	550	23	140 @ 14A, 10V	192	TO-247-3	Last Time Buy
IXFH36N50P	IXYS	500	36	170 @ 500mA, 10V	540	TO-247-3	Active
IXFH44N50P	IXYS	500	44	140 @ 22A, 10V	658	TO-247-3	Active
IXFR44N50Q3	IXYS	500	25	154 @ 22A, 10V	300	TO-247-3	Active
IXTH30N50L	IXYS	500	30	200 @ 15A, 10V	400	TO-247-3	Active
IXTH30N50L2	IXYS	500	30	200 @ 15A, 10V	400	TO-247-3	Active
IXTH40N50L2	IXYS	500	40	170 @ 20A, 10V	540	TO-247-3	Active
IXTX46N50L	IXYS	500	46	160 @ 500mA, 20V	700	TO-247-3 Variant	Active
STW28NM50N	STMicroelectronics	500	21	158 @ 10.5A, 10V	150	TO-247-3	Active
STW32NM50N	STMicroelectronics	500	22	130 @ 11A, 10V	190	TO-247-3	Active

Engineering Selection Recommendations

Direct Electrical Equivalents (Recommended Priority):

The IXFH36N50P and IXTH40N50L2 provide the closest electrical alignment to the IRFPS35N50LPBF. Both devices maintain the 500V Vdss rating, exceed the 34A continuous drain current requirement, and deliver power dissipation ratings (540W and 540W respectively) that match or exceed the original 450W specification. Both parts are classified as Active products, ensuring long-term availability and supply chain stability. The IXFH36N50P is rated at 36A with 540W dissipation, while the IXTH40N50L2 is rated at 40A with 540W dissipation, providing margin above the original specification.

Secondary Alternatives (Current-Limited Applications):

The IXFH44N50P offers superior current handling at 44A and improved on-resistance (140mOhm) compared to the original 145mOhm specification, with 658W power dissipation. This part is suitable for applications requiring higher current capacity. The IXTH30N50L and IXTH30N50L2 provide 30A continuous current with 400W dissipation, acceptable for applications with lower current demands than the original 34A rating.

Voltage-Elevated Alternative:

The IPW50R140CPFKSA1 from Infineon Technologies offers a higher voltage rating (550V) with lower continuous current (23A) and reduced power dissipation (192W). This part is classified as Last Time Buy and should be selected only when the elevated voltage rating is required and current/power requirements are compatible with the 23A/192W specifications.

Lower-Current Alternatives (Derating Applications):

The STW28NM50N and STW32NM50N from STMicroelectronics provide 21A and 22A continuous current respectively, with significantly reduced power dissipation (150W and 190W). These parts are suitable only for applications where the original 34A current requirement can be reduced or where thermal constraints limit power dissipation.

Package Compatibility:

All recommended substitutes employ through-hole mounting in TO-247-3 or equivalent packages. Mechanical verification is required to confirm fit within existing PCB layouts designed for the original SUPER-247™ (TO-274AA) package, as dimensional differences may exist between package variants.

Compliance Verification:

All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, ensuring regulatory alignment with the original component specification.

Frequently Asked Questions (FAQ)

Q: Can the IXFH36N50P directly replace the IRFPS35N50LPBF without circuit modification?

A: The IXFH36N50P maintains electrical compatibility with the IRFPS35N50LPBF across all critical parameters: 500V Vdss, 36A continuous current (exceeding the original 34A), and 540W power dissipation (exceeding the original 450W). Package differences between TO-274AA and TO-247-3 require mechanical verification for PCB fit. Gate charge and input capacitance values differ slightly but remain within acceptable ranges for most applications. Circuit-level testing is recommended to confirm performance in the specific application.

Q: What is the primary reason the IRFPS35N50LPBF is classified as obsolete?

A: The IRFPS35N50LPBF is marked as obsolete, indicating that Vishay Siliconix has discontinued production and will not accept new orders. Active alternatives from IXYS and STMicroelectronics provide equivalent or superior electrical performance with assured long-term availability.

Q: Are there current limitations when substituting with lower-rated devices?

A: Yes. The STW28NM50N (21A) and STW32NM50N (22A) are rated below the original 34A specification. These parts are suitable only for applications where continuous drain current can be reduced or where the circuit design permits operation at reduced current levels. Exceeding the rated continuous current of any substitute part will result in thermal stress and potential device failure.

Q: How do package differences affect substitution?

A: The original IRFPS35N50LPBF uses the SUPER-247™ (TO-274AA) package. Substitute parts employ TO-247-3, TO-247AD, ISOPLUS247™, or PLUS247™-3 packages. While all are through-hole packages with similar thermal and electrical characteristics, physical dimensions and pin configurations may differ. PCB layout verification is required to confirm mechanical fit, lead spacing, and mounting hole alignment before substitution.

Q: Which substitute part offers the best on-resistance performance?

A: The IXFH44N50P and STW32NM50N both offer 140mOhm and 130mOhm on-resistance respectively, compared to the original 145mOhm specification. The STW32NM50N provides the lowest on-resistance but is limited to 22A continuous current. The IXFH44N50P combines low on-resistance (140mOhm) with higher current capacity (44A), making it suitable for applications requiring both low conduction losses and high current handling.

Q: Is the IPW50R140CPFKSA1 suitable as a direct replacement?

A: The IPW50R140CPFKSA1 is not recommended as a direct replacement for applications requiring 34A continuous current. This Infineon part is rated for only 23A continuous current and 192W power dissipation, both significantly below the original specification. The elevated voltage rating (550V) provides no benefit in 500V applications. This part is suitable only for applications where current requirements are 23A or lower and where the Last Time Buy status is acceptable.

Q: What compliance certifications should be verified before substitution?

A: All substitute parts listed maintain ROHS3 compliance and REACH unaffected status, matching the original IRFPS35N50LPBF specification. Verify that the selected substitute part carries these certifications in the component datasheet before procurement. Additional certifications or compliance requirements specific to the end application should be confirmed with the component manufacturer.

Q: How does gate charge affect circuit performance during substitution?

A: Gate charge values vary among substitute parts, ranging from 50nC (STW28NM50N) to 320nC (IXTH40N50L2), compared to the original 230nC specification. Higher gate charge requires longer switching times and increased driver current capability. Lower gate charge enables faster switching. Circuit driver design must accommodate the gate charge of the selected substitute part. Switching frequency and thermal performance may be affected by these differences.

Q: Are there thermal considerations when selecting a substitute part?

A: Yes. Power dissipation ratings vary significantly among substitutes, from 150W (STW28NM50N) to 700W (IXTX46N50L). The original IRFPS35N50LPBF is rated for 450W. Substitute parts with lower power dissipation ratings require more aggressive thermal management or reduced operating current. Parts with higher ratings provide thermal margin. Verify that the selected substitute part's thermal characteristics are compatible with the application's cooling design and ambient temperature environment.

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