STB85NF3LLT4 Equivalent & Substitute Parts

Part Overview

The STB85NF3LLT4 is an N-Channel 30V 85A MOSFET manufactured by STMicroelectronics in the STripFET™ II series, housed in a D2PAK surface mount package. This device is rated for 110W power dissipation and operates across a temperature range of -65°C to 175°C. The part is currently classified as obsolete, necessitating identification of functionally equivalent alternatives for ongoing production and maintenance applications. Substitute parts must maintain compatibility with the D2PAK package format and preserve the critical electrical parameters required for circuit operation.

Substiute Parts

STB85NF3LLT4

STMicroelectronicsIn Stock: 29159STB85NF3LLT4 Datasheet

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IRF3709ZSTRRPBF

Infineon TechnologiesIn Stock: 3231IRF3709ZSTRRPBF Datasheet

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IRL3803STRLPBF

Infineon TechnologiesIn Stock: 6627IRL3803STRLPBF Datasheet

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PSMN017-30BL,118

Nexperia USA Inc.In Stock: 2850PSMN017-30BL,118 Datasheet

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PSMN4R3-30BL,118

Nexperia USA Inc.In Stock: 10797PSMN4R3-30BL,118 Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the STB85NF3LLT4 is determined by strict adherence to the following electrical and mechanical parameters:

Critical Matching Parameters:

• Drain to Source Voltage (Vdss): 30V minimum
• Package Format: D2PAK surface mount (TO-263-3)
• FET Type: N-Channel MOSFET
• Mounting Type: Surface Mount
• RoHS Compliance: ROHS3 Compliant

Performance Compatibility Parameters:

• Continuous Drain Current (Id): Equal to or greater than 85A
• Rds On (Max): Equal to or less than 8mOhm at specified conditions
• Power Dissipation: Equal to or greater than 110W
• Gate Charge (Qg): Comparable to 40nC for drive circuit compatibility
• Operating Temperature: Minimum -55°C to 175°C

Substitute parts are grouped based on their ability to meet or exceed these parameters while maintaining identical package geometry and electrical interface requirements. Parts with lower current ratings or higher on-resistance are listed for reference but represent functional limitations in high-current applications.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute: PSMN4R3-30BL,118

The PSMN4R3-30BL,118 manufactured by Nexperia USA Inc. is the recommended substitute for the STB85NF3LLT4. This part maintains the 30V Vdss rating and D2PAK package format while providing 100A continuous drain current, exceeding the original 85A specification. The device delivers superior on-resistance performance at 4.1mOhm and maintains comparable power dissipation at 103W. The PSMN4R3-30BL,118 holds Active product status, ensuring long-term availability and supply chain stability. Full ROHS3 compliance and identical MSL rating (1 - Unlimited) confirm environmental and handling compatibility.

Secondary Substitute: IRL3803STRLPBF

The IRL3803STRLPBF from Infineon Technologies provides the highest current capability at 140A with superior on-resistance of 6mOhm and maximum power dissipation of 200W. This part accommodates applications requiring higher current margins or thermal headroom. However, the device carries a "Not For New Designs" status and exhibits significantly higher gate charge (140nC), which may require drive circuit evaluation. The part remains ROHS3 compliant and suitable for legacy system maintenance.

Tertiary Substitute: IRF3709ZSTRRPBF

The IRF3709ZSTRRPBF from Infineon Technologies offers 87A continuous drain current with improved on-resistance of 6.3mOhm and reduced gate charge of 26nC. This part provides a close electrical match to the original device with lower drive requirements. The "Not For New Designs" status and reduced power dissipation rating of 79W limit its application to lower-power circuit variants. ROHS3 compliance is maintained.

Not Recommended: PSMN017-30BL,118

The PSMN017-30BL,118 is unsuitable as a primary substitute due to its 32A continuous drain current rating, which falls significantly below the 85A requirement. While the part maintains D2PAK packaging and 30V Vdss rating, the reduced current capacity and higher on-resistance of 17mOhm restrict its use to lower-current applications only. The obsolete product status further limits its viability.

Frequently Asked Questions (FAQ)

Q: Can the PSMN4R3-30BL,118 directly replace the STB85NF3LLT4 without circuit modifications?

A: The PSMN4R3-30BL,118 maintains identical Vdss (30V), package format (D2PAK), and pin configuration, enabling direct mechanical and electrical substitution. The higher current rating (100A vs. 85A) and improved on-resistance (4.1mOhm vs. 8mOhm) provide enhanced performance margins. Gate charge values are comparable (41.5nC vs. 40nC), ensuring compatible drive circuit operation. No circuit modifications are required for standard applications.

Q: Why is the IRL3803STRLPBF not recommended as the primary substitute despite superior specifications?

A: While the IRL3803STRLPBF exceeds performance specifications with 140A current rating and 200W power dissipation, its "Not For New Designs" status indicates manufacturer discontinuation trajectory. The significantly elevated gate charge of 140nC (3.5× the original) requires drive circuit verification to prevent switching losses and thermal stress. For new designs and long-term production, the Active-status PSMN4R3-30BL,118 provides superior supply chain assurance.

Q: Are all substitute parts compatible with the original D2PAK footprint?

A: All listed substitute parts utilize the D2PAK (TO-263-3) package format with identical lead configuration (2 Leads + Tab). PCB footprints and thermal pad dimensions are standardized across all parts, enabling direct mechanical substitution without layout modifications.

Q: What is the significance of the "Not For New Designs" product status?

A: "Not For New Designs" indicates that the manufacturer has ceased active development and is transitioning the part toward end-of-life. While existing inventory remains available, long-term supply cannot be guaranteed. For production applications requiring multi-year component availability, parts with Active status (such as PSMN4R3-30BL,118) are preferred.

Q: How do gate charge differences affect circuit performance?

A: Gate charge (Qg) determines the energy required to switch the MOSFET on and off. The STB85NF3LLT4 requires 40nC at 4.5V. The PSMN4R3-30BL,118 requires 41.5nC at 10V, representing comparable drive requirements. The IRL3803STRLPBF requires 140nC, necessitating verification that the gate driver circuit can supply sufficient current within the required switching time window. Higher gate charge increases switching losses and may require driver circuit upgrades.

Q: What compliance certifications are maintained across all substitute parts?

A: All substitute parts maintain ROHS3 compliance, confirming restriction of hazardous substances per EU Directive 2011/65/EU. All parts carry MSL rating of 1 (Unlimited), indicating no moisture sensitivity restrictions during storage and handling. REACH status is "REACH Unaffected" across all parts, confirming no substances of very high concern (SVHC) are present above regulatory thresholds.

Q: Can the PSMN017-30BL,118 be used in applications requiring lower current?

A: The PSMN017-30BL,118 is suitable only for applications where the required continuous drain current does not exceed 32A. The part maintains 30V Vdss and D2PAK packaging but exhibits higher on-resistance (17mOhm) and reduced power dissipation capability (47W). Use of this part in circuits designed for 85A operation will result in thermal stress, component failure, and circuit malfunction. Current rating verification is mandatory before selection.