MOSFET Selection for High-Voltage Power Applications: STW6N90K5, STH6N95K5-2 vs. China Alternatives VBP19R05S, VBL19R07S
In high-voltage power conversion and switching designs, selecting a MOSFET that balances voltage rating, conduction loss, and thermal 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, STW6N90K5 (TO-247) and STH6N95K5-2 (H2PAK-2), as benchmarks. We will deeply analyze their design cores and application scenarios, and comparatively evaluate two domestic alternative solutions, VBP19R05S and VBL19R07S. By clarifying their parameter differences and performance orientations, we aim to provide a clear selection map to help you find the most suitable high-voltage switching solution in the complex component landscape.
Comparative Analysis: STW6N90K5 (N-channel, TO-247) vs. VBP19R05S
Analysis of the Original Model (STW6N90K5) Core:
This is a 900V N-channel MOSFET from STMicroelectronics, featuring the MDmesh K5 superjunction technology in a through-hole TO-247 package. Its design core is to deliver robust performance and high voltage ruggedness in applications requiring high reliability. Key advantages include: a high drain-source voltage (Vdss) of 900V, a continuous drain current (Id) of 6A, and a relatively low on-resistance (RDS(on)) of 1.1Ω (typical 0.91Ω) at 10V gate drive. The TO-247 package offers excellent thermal dissipation capability for handling power losses.
Compatibility and Differences of the Domestic Alternative (VBP19R05S):
VBsemi's VBP19R05S is also offered in a TO-247 package, providing direct pin-to-pin and form-factor compatibility. The key differences are in the electrical parameters: while it matches the 900V voltage rating, the VBP19R05S has a slightly lower continuous current rating of 5A and a higher on-resistance of 1500mΩ (1.5Ω) at 10V. This indicates the original model holds an advantage in conduction loss for the same current level.
Key Application Areas:
Original Model STW6N90K5: Its high voltage rating and good RDS(on) balance make it suitable for high-voltage, medium-current switching. Typical applications include:
Switched-Mode Power Supplies (SMPS): PFC stages, flyback, or forward converters in offline power supplies.
Industrial controls: Motor drives, solenoid drivers, and inverter circuits.
Lighting: High-voltage ballasts and LED driver circuits.
Alternative Model VBP19R05S: Serves as a viable alternative in applications where the full 6A current of the original is not required, or where cost and supply chain diversification are priorities, while maintaining the 900V withstand capability.
Comparative Analysis: STH6N95K5-2 (N-channel, H2PAK-2) vs. VBL19R07S
This comparison shifts focus to a surface-mount solution for high-voltage applications, where the design pursuit is a balance of 'high voltage, low resistance, and compact footprint'.
Analysis of the Original Model (STH6N95K5-2) Core:
This model from STMicroelectronics utilizes an H2PAK-2 (TO-263-like) surface-mount package with the same MDmesh K5 technology. Its core advantages are:
High Voltage Performance: A 950V drain-source voltage rating, suitable for harsh line conditions.
Optimized Conduction: An on-resistance of 1.25Ω at 10V gate drive and 3A, with a typical value of 1Ω, providing efficient conduction for a 6A device.
Surface-Mount Advantage: The H2PAK-2 package offers a good compromise between thermal performance (via a large exposed pad) and board space savings, ideal for modern, automated assembly.
The domestic alternative VBL19R07S presents a compelling "performance-enhanced" option in key areas: It offers a comparable 900V voltage rating but achieves significant improvements in other specs: a higher continuous current rating of 7A and a substantially lower on-resistance of 950mΩ (0.95Ω) at 10V. This translates to potentially lower conduction losses and higher current-handling capability in a similar TO-263 package footprint.
Key Application Areas:
Original Model STH6N95K5-2: Its high voltage (950V), 6A current, and surface-mount form factor make it ideal for space-constrained, high-voltage applications:
Compact SMPS designs: Especially in auxiliary power supplies or high-density AC-DC modules.
Telecom and server power: Intermediate bus converters or secondary-side synchronous rectification (in appropriate topologies).
Automotive systems: High-voltage auxiliary systems in electric vehicles (requiring specific qualification).
Alternative Model VBL19R07S: Is highly suitable for upgrade or new designs where lower conduction loss (lower RDS(on)) and higher continuous current (7A) are desired, potentially enabling higher efficiency or power density in similar 900V-rated applications.
Conclusion
In summary, this analysis reveals two distinct selection pathways for high-voltage MOSFETs:
For through-hole applications demanding 900V ruggedness and proven reliability, the original model STW6N90K5, with its 6A current and 1.1Ω RDS(on), remains a strong choice for industrial SMPS and motor drives. Its domestic alternative VBP19R05S provides package-compatible substitution with a focus on cost and supply chain diversification, suitable for applications where the current demand is within 5A.
For surface-mount applications requiring high voltage capability, the original model STH6N95K5-2, with its 950V rating and H2PAK-2 package, is an excellent choice for compact, high-voltage power supplies. The domestic alternative VBL19R07S emerges as a performance-enhanced option, offering a lower 0.95Ω RDS(on) and higher 7A current in a similar package, making it attractive for designs prioritizing efficiency and current capacity.
The core conclusion is that selection hinges on precise requirement matching. In the context of supply chain diversification, domestic alternatives not only provide feasible backups but also offer parameter-specific enhancements, giving engineers greater flexibility and resilience in design trade-offs and cost management. Understanding the design philosophy and parameter implications of each device is essential to unlocking its full value in the circuit.