MOSFET Selection for High-Voltage Power Applications: STU2NK100Z, STW65N80K5 vs. China Alternatives VBFB195R03, VBP18R47S
In high-voltage power design, selecting a MOSFET that balances voltage withstand, current capability, and switching performance is a critical engineering challenge. This goes beyond simple part substitution, requiring careful trade-offs among ruggedness, efficiency, cost, and supply chain security. This article uses two representative high-voltage MOSFETs—STU2NK100Z and STW65N80K5—as benchmarks. We will delve into their design cores and application scenarios, followed by a comparative evaluation of their domestic alternatives, VBFB195R03 and VBP18R47S. By clarifying parameter differences and performance orientations, we aim to provide a clear selection guide for your next high-voltage power design.
Comparative Analysis: STU2NK100Z (N-channel) vs. VBFB195R03
Analysis of the Original Model (STU2NK100Z) Core:
This is a 1kV N-channel MOSFET from STMicroelectronics, utilizing SuperMESH technology in a TO-251-3 package. Its design core focuses on providing robust high-voltage switching with enhanced ruggedness. Key advantages include a high drain-source voltage (Vdss) of 1000V, integrated Zener protection for gate safety, and optimized dynamic performance with high dV/dt capability. The on-resistance is 8.5Ω at 10V gate drive, with a continuous drain current of 1.85A.
Compatibility and Differences of the Domestic Alternative (VBFB195R03):
VBsemi's VBFB195R03 is a pin-to-pin compatible alternative in a TO-251 package. The main differences are in electrical parameters: VBFB195R03 has a slightly lower voltage rating (950V vs. 1000V) but offers a significantly lower on-resistance of 5.4Ω (5400mΩ) at 10V and a higher continuous current rating of 3A. It uses planar technology, providing a cost-effective and reliable solution.
Key Application Areas:
Original Model STU2NK100Z: Ideal for applications demanding the full 1000V rating and the enhanced ruggedness of SuperMESH technology, such as:
High-voltage offline switchers and SMPS primary-side circuits.
Zener-protected switching in industrial controls.
Applications where high dV/dt capability is critical.
Alternative Model VBFB195R03: Suited for applications where 950V rating is sufficient, and benefits from lower conduction loss (lower RDS(on)) and higher current capability (3A). A strong alternative for cost-sensitive 800V-950V designs like:
Switch Mode Power Supplies (SMPS).
Power factor correction (PFC) stages.
Industrial and lighting ballast circuits.
Comparative Analysis: STW65N80K5 (N-channel) vs. VBP18R47S
This comparison shifts to higher-power, medium-voltage applications where low conduction loss and high current handling are paramount.
Analysis of the Original Model (STW65N80K5) Core:
This 800V N-channel MOSFET from ST uses MDmesh K5 technology in a TO-247 package. Its core advantages are:
Excellent Conduction Performance: Very low typical on-resistance of 70mΩ at 10V gate drive, supporting a high continuous drain current of 46A.
Advanced Technology: The MDmesh K5 platform offers an optimal balance of low RDS(on), reduced gate charge, and improved switching performance.
Robust Package: The TO-247 package provides excellent thermal performance for high-power dissipation.
Compatibility and Differences of the Domestic Alternative (VBP18R47S):
VBsemi's VBP18R47S is a direct pin-to-pin compatible alternative in a TO-247 package. It represents a "performance-competitive" choice:
It matches the 800V voltage rating.
It offers a comparable continuous current rating of 47A.
Its on-resistance is specified at 90mΩ (typical), which is slightly higher than the ST part's 70mΩ but remains very competitive for the voltage class. It utilizes SJ_Multi-EPI technology for good switching characteristics.
Key Application Areas:
Original Model STW65N80K5: An excellent choice for high-efficiency, high-power applications requiring the proven performance of MDmesh K5, such as:
Primary switches in high-power SMPS and server PSUs.
Motor drives and inverters for industrial equipment.
High-power PFC and LLC resonant converter stages.
Alternative Model VBP18R47S: A viable domestic alternative for 800V applications where a TO-247 package is used, offering similar current capability and a competitive RDS(on). Suitable for:
High-power switching power supplies.
Motor control and drives.
UPS and inverter systems.
Conclusion
In summary, this analysis reveals two distinct selection pathways for high-voltage designs:
For ultra-high-voltage (~1kV) applications where voltage rating and ruggedness are critical, the original STU2NK100Z with its 1000V rating and SuperMESH technology holds a key advantage. Its domestic alternative VBFB195R03 provides a compelling option with a lower on-resistance and higher current at a 950V rating, ideal for cost-optimized designs where the full 1000V is not strictly required.
For high-power 800V applications, the original STW65N80K5 sets a high standard with its very low 70mΩ RDS(on) and 46A current in a TO-247 package. The domestic alternative VBP18R47S offers a closely matched performance profile (47A, 90mΩ) with pin-to-pin compatibility, providing a resilient and cost-effective alternative for power supplies, motor drives, and inverters.
The core takeaway is that selection is driven by precise requirement matching. In the context of supply chain diversification, domestic alternatives like VBFB195R03 and VBP18R47S not only offer viable backup options but also present competitive performance, giving engineers greater flexibility in design trade-offs and cost control. Understanding the specific demands of your voltage, current, and loss budget is essential to selecting the optimal MOSFET for your high-voltage power stage.