STP8NK85Z N-Channel MOSFET 850V 6.7A Equivalent & Substitute Parts

Part Overview

The STP8NK85Z is an N-Channel MOSFET manufactured by STMicroelectronics, rated for 850V drain-to-source voltage with 6.7A continuous drain current at 25°C. This device is packaged in a TO-220-3 through-hole configuration and belongs to the SuperMESH™ series. The STP8NK85Z is classified as obsolete, making identification of equivalent and substitute parts necessary for ongoing design support and component procurement. Substitute parts must maintain functional compatibility within high-voltage switching applications while accommodating the through-hole TO-220 package format.

Substiute Parts

STP8NK85Z

STMicroelectronicsIn Stock: 848STP8NK85Z Datasheet

Current PartRFQ

STP9NK90Z

STMicroelectronicsIn Stock: 8135STP9NK90Z Datasheet

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FQP9N90C

onsemiIn Stock: 1692FQP9N90C Datasheet

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Key Parameters

Substitute Part Grouping Explanation

Substitution of the STP8NK85Z is determined by the following critical electrical and mechanical parameters:

Voltage Rating Compatibility: Substitute parts must have a Vdss rating equal to or greater than 850V. This ensures the device can withstand the maximum drain-to-source voltage in the application circuit.

Current Rating Compatibility: Substitute parts must have a continuous drain current (Id) rating equal to or greater than 6.7A at 25°C. This ensures the device can handle the required load current without thermal stress.

Package Compatibility: All substitute parts must use the TO-220-3 through-hole package format to ensure mechanical and electrical compatibility with existing PCB layouts and thermal management solutions.

Gate Drive Voltage: Substitute parts must operate with a maximum Rds On specification at 10V gate drive voltage, ensuring compatibility with standard gate driver circuits.

Temperature Range: Substitute parts must support the operating temperature range of -55°C to 150°C (TJ) to maintain functional performance across the application environment.

Compliance Requirements: All substitute parts must maintain ROHS3 compliance and REACH unaffected status to satisfy regulatory and supply chain requirements.

The identified substitute parts (STP9NK90Z and FQP9N90C) meet or exceed all critical parameters while maintaining the same package format and compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

STP9NK90Z (STMicroelectronics): This substitute part is manufactured by the same supplier as the original STP8NK85Z and belongs to the same SuperMESH™ series. The STP9NK90Z provides a 50V higher voltage rating (900V vs. 850V) and 1.3A higher continuous drain current (8A vs. 6.7A), delivering improved performance margins. Power dissipation capability increases from 150W to 160W. The device maintains identical gate drive voltage specifications and operating temperature range. Product status is active, ensuring long-term availability and supply chain stability. ROHS3 compliance and REACH unaffected status are maintained. This part is the preferred substitute when design requirements allow for the higher voltage and current ratings.

FQP9N90C (onsemi): This substitute part is manufactured by onsemi under the QFET® series designation. The FQP9N90C provides a 50V higher voltage rating (900V vs. 850V) and 1.3A higher continuous drain current (8A vs. 6.7A). Power dissipation capability is significantly higher at 205W compared to 150W. Gate drive voltage specifications remain compatible at 10V. Operating temperature range matches the original device. Product status is active with confirmed availability. ROHS3 compliance is maintained. The higher power dissipation rating provides additional thermal headroom for demanding applications. This part is suitable when cross-manufacturer substitution is acceptable and enhanced thermal performance is beneficial.

Both substitute parts satisfy all mandatory compatibility criteria: TO-220-3 package format, voltage and current ratings equal to or exceeding the original specification, compatible gate drive voltage, matching operating temperature range, and equivalent regulatory compliance.

Frequently Asked Questions (FAQ)

Q: Can the STP9NK90Z directly replace the STP8NK85Z in existing circuit designs?

A: Yes. The STP9NK90Z maintains identical package format (TO-220-3), gate drive voltage (10V), operating temperature range (-55°C to 150°C), and pin configuration. The higher voltage rating (900V vs. 850V) and increased current capacity (8A vs. 6.7A) provide design margin without requiring circuit modifications. Both devices are N-Channel MOSFETs with compatible threshold voltage and gate charge characteristics.

Q: What are the key differences between the STP9NK90Z and FQP9N90C substitutes?

A: Both devices share identical voltage (900V) and current (8A) ratings and use the TO-220-3 package. The primary differences are manufacturer (STMicroelectronics vs. onsemi), series designation (SuperMESH™ vs. QFET®), and power dissipation rating (160W vs. 205W). The FQP9N90C offers higher thermal capacity. Input capacitance differs slightly (2115 pF vs. 2730 pF at 25V), which may affect gate drive circuit performance in high-frequency switching applications.

Q: Why is the STP8NK85Z classified as obsolete?

A: The STP8NK85Z is listed as obsolete by the manufacturer. Substitute parts with active product status (STP9NK90Z and FQP9N90C) are recommended for new designs and ongoing procurement to ensure long-term supply chain availability and manufacturer support.

Q: Are there any thermal management considerations when substituting these parts?

A: The substitute parts provide equal or higher power dissipation ratings (160W and 205W vs. 150W), indicating improved thermal performance. Existing thermal management solutions designed for the STP8NK85Z remain suitable for the substitute parts. The TO-220-3 package format is identical across all three devices, maintaining compatibility with existing heatsink mounting configurations.

Q: Do the substitute parts require different gate driver circuits?

A: No. All three devices operate with a maximum Rds On specification at 10V gate drive voltage. Gate driver circuits designed for the STP8NK85Z are directly compatible with both STP9NK90Z and FQP9N90C substitutes. Gate charge specifications are similar (60 nC, 72 nC, and 58 nC respectively), ensuring comparable switching performance.

Q: What compliance certifications apply to the substitute parts?

A: Both substitute parts maintain ROHS3 compliance and REACH unaffected status, matching the regulatory requirements of the original STP8NK85Z. These certifications ensure compatibility with environmental and supply chain regulations applicable to the original device.

Q: Can the FQP9N90C be used in applications originally designed for the STP8NK85Z?

A: Yes. The FQP9N90C meets all mandatory compatibility criteria: TO-220-3 package, 900V voltage rating (exceeds 850V requirement), 8A current rating (exceeds 6.7A requirement), 10V gate drive voltage, and -55°C to 150°C operating temperature range. Cross-manufacturer substitution is electrically and mechanically valid. The higher power dissipation rating (205W) provides additional thermal margin.