STS15N4LLF3 Equivalent & Substitute Parts

Part Overview

The STS15N4LLF3 is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 40V drain-to-source voltage with 15A continuous drain current. This device is part of the STripFET™ series and is housed in an 8-SOIC surface mount package. The part is classified as obsolete, necessitating identification of equivalent alternatives for new designs and ongoing production requirements. Substitute parts must maintain compatibility across electrical ratings, thermal characteristics, and mechanical packaging to ensure direct replacement capability.

Substiute Parts

STS15N4LLF3

STMicroelectronicsIn Stock: 4272STS15N4LLF3 Datasheet

Current PartRFQ

FDS8842NZ

onsemiIn Stock: 2723FDS8842NZ Datasheet

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IRF8113TRPBF

Infineon TechnologiesIn Stock: 24273IRF8113TRPBF Datasheet

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IRF8736TRPBF

Infineon TechnologiesIn Stock: 503500IRF8736TRPBF Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the STS15N4LLF3 is determined by the following critical electrical and mechanical parameters:

Primary Compatibility Criteria:

• Drain-to-Source Voltage (Vdss): Substitute parts must equal or exceed 40V
• Continuous Drain Current (Id): Substitute parts must equal or exceed 15A at 25°C
• On-State Resistance (Rds On): Substitute parts must not significantly exceed 5mOhm at rated conditions to maintain thermal performance
• Package Type: 8-SOIC surface mount package required for mechanical compatibility
• Operating Temperature Range: -55°C to 150°C minimum

Substitution Logic: Parts are grouped as equivalent when they satisfy all primary criteria. Parts that exceed the voltage or current ratings while maintaining the same package and thermal envelope are classified as direct substitutes. Parts with reduced voltage ratings (30V vs. 40V) are classified as conditional substitutes, suitable only for applications where the lower voltage rating is acceptable.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: FDS8842NZ (onsemi)

The FDS8842NZ is the optimal substitute for the STS15N4LLF3. Both devices share identical voltage ratings (40V Vdss), equivalent current ratings (14.9A vs. 15A), and matching package specifications (8-SOIC). The FDS8842NZ maintains active product status, ensuring long-term availability and supply chain stability. Both parts are ROHS3 compliant and carry identical moisture sensitivity levels. The slightly higher on-state resistance (7mOhm vs. 5mOhm) is within acceptable engineering tolerance for most applications. This part is recommended for new designs and production transitions.

Secondary Substitute: IRF8736TRPBF (Infineon Technologies)

The IRF8736TRPBF is suitable as a substitute where the reduced voltage rating (30V vs. 40V) is acceptable for the application. This device offers superior on-state resistance (4.8mOhm) and lower gate charge (26nC), providing improved switching efficiency. The IRF8736TRPBF maintains active product status and is available in high volume. Use this substitute only in applications where the 30V voltage rating does not compromise circuit performance or safety margins.

Conditional Substitute: IRF8113TRPBF (Infineon Technologies)

The IRF8113TRPBF shares the 30V voltage rating limitation with the IRF8736TRPBF and carries a "Not For New Designs" product status. While electrically compatible for reduced-voltage applications, this part is not recommended for new designs due to its obsolescence trajectory. Existing designs currently using this part may continue operation, but migration to the IRF8736TRPBF is advised for long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can the FDS8842NZ directly replace the STS15N4LLF3 without circuit modifications?

A: Yes. The FDS8842NZ maintains identical voltage and current ratings, matching package type, and compatible thermal specifications. Direct substitution is possible without circuit redesign.

Q: What is the significance of the voltage rating difference between the STS15N4LLF3 (40V) and the Infineon alternatives (30V)?

A: The 40V rating provides a 33% higher voltage margin compared to the 30V alternatives. Applications operating near 30V supply levels or experiencing voltage transients require the 40V-rated device. Applications with supply voltages below 25V can safely use the 30V-rated substitutes.

Q: Why does the FDS8842NZ have higher on-state resistance (7mOhm) compared to the STS15N4LLF3 (5mOhm)?

A: On-state resistance varies with device geometry and manufacturing process. The 2mOhm difference results in approximately 40% higher conduction losses at rated current. Thermal analysis of the specific application determines whether this difference is acceptable.

Q: Are all substitute parts available in the same packaging format?

A: Yes. All listed substitutes use the 8-SOIC surface mount package with identical mechanical dimensions (0.154" width, 3.90mm). PCB footprints are directly compatible.

Q: What is the difference between "Active" and "Not For New Designs" product status?

A: Active status indicates the manufacturer continues production and supports the part for new applications. "Not For New Designs" indicates the manufacturer is phasing out the part and recommends alternatives for new projects, though existing inventory may remain available.

Q: Do all substitute parts meet the same compliance standards as the STS15N4LLF3?

A: Yes. All listed substitutes are ROHS3 compliant, REACH unaffected, and carry EAR99 ECCN classification, matching the compliance profile of the original part.

Q: Which substitute offers the best switching performance?

A: The IRF8736TRPBF provides the lowest gate charge (26nC) and on-state resistance (4.8mOhm), resulting in faster switching transitions and lower conduction losses. This advantage applies only to applications where the 30V voltage rating is acceptable.