MOSFET Selection for High-Voltage Power Applications: STF7N105K5, STF10N95K5 vs. China Alternatives VBMB195R03, VBMB19R11S
In high-voltage power conversion and switching designs, selecting a MOSFET that balances voltage rating, conduction loss, and cost is a critical challenge for engineers. This goes beyond simple part substitution—it requires careful trade-offs among performance, ruggedness, and supply chain availability. This article takes two representative high-voltage MOSFETs, STF7N105K5 and STF10N95K5, as benchmarks, analyzes their design focus and application scenarios, and evaluates two domestic alternative solutions, VBMB195R03 and VBMB19R11S. By clarifying parameter differences and performance orientations, we aim to provide a clear selection guide to help you find the most suitable high-voltage switching solution for your next design.
Comparative Analysis: STF7N105K5 (N-channel) vs. VBMB195R03
Analysis of the Original Model (STF7N105K5) Core:
This is a 1050V N-channel MOSFET from STMicroelectronics, in a TO-220FP package. Its design core is to provide robust high-voltage blocking capability in a standard isolated package. Key advantages are: a high drain-source voltage (Vdss) of 1050V, a continuous drain current (Id) of 4A, and a typical on-resistance (RDS(on)) of 1.4Ω. It uses the MDmesh K5 technology, offering a good balance between high-voltage performance and switching characteristics for medium-power off-line applications.
Compatibility and Differences of the Domestic Alternative (VBMB195R03):
VBsemi's VBMB195R03 is offered in a TO-220F package and serves as a functional alternative. The main differences are in electrical parameters: VBMB195R03 has a slightly lower voltage rating (950V vs. 1050V) and a higher on-resistance (5400mΩ @10V vs. ~2000mΩ @10V for the ST part). Its continuous current rating is also lower at 3A.
Key Application Areas:
Original Model STF7N105K5: Suitable for applications requiring very high voltage blocking up to 1050V with moderate current, such as:
Auxiliary power supplies in industrial systems.
Switching stages in medium-power offline SMPS (e.g., for appliances).
Snubber circuits or high-side switches in high-voltage circuits.
Alternative Model VBMB195R03: More suitable for applications where 950V rating is sufficient and current demands are lower (around 3A), or where cost optimization is a priority for high-voltage switching functions.
Comparative Analysis: STF10N95K5 (N-channel) vs. VBMB19R11S
This comparison focuses on higher-current capability within the high-voltage segment. The design pursuit here is a better balance of "voltage rating, current, and on-resistance."
Analysis of the Original Model (STF10N95K5) Core:
This 950V N-channel MOSFET from ST also uses MDmesh K5 technology in a TO-220FP-3 package. Its core advantages are:
High Current Capability: A continuous drain current of 8A, suitable for higher power stages.
Low On-Resistance: A typical RDS(on) of 0.65Ω (800mΩ @10V per datasheet), which reduces conduction losses significantly compared to the 1050V part.
Robust Package: The TO-220FP package provides good thermal performance for its power class.
The domestic alternative VBMB19R11S presents a compelling "performance-comparable" option: It matches the 900V voltage class closely and offers a superior continuous current rating of 11A. Crucially, its on-resistance is very competitive at 580mΩ @10V. It utilizes SJ_Multi-EPI (Super Junction Multi-Epitaxial) technology, which is designed for high-efficiency high-voltage switching.
Key Application Areas:
Original Model STF10N95K5: Its 8A current and low RDS(on) make it well-suited for higher-power high-voltage applications, such as:
Main switches in offline power supplies (e.g., PFC stages, flyback/forward converters).
Motor drives for industrial equipment operating from high-voltage buses.
Inverters for renewable energy systems.
Alternative Model VBMB19R11S: With its higher current (11A) and low on-resistance, it is an excellent choice for applications demanding high efficiency and current handling in the ~900V range. It is suitable for direct upgrades or new designs in:
High-efficiency server/telecom SMPS.
High-power LED lighting drivers.
Solar microinverters.
Summary
This analysis reveals two distinct selection paths for high-voltage applications:
For applications requiring the highest voltage blocking (1050V) with moderate current, the original STF7N105K5 remains a strong choice. Its domestic alternative VBMB195R03, with a 950V rating and higher RDS(on), is suitable for cost-sensitive designs where the full 1050V rating is not essential.
For applications around the 900-950V range where current capability and low conduction loss are priorities, the original STF10N95K5 offers solid performance. The domestic alternative VBMB19R11S emerges as a highly competitive option, providing higher current (11A vs. 8A) and comparably low on-resistance, making it attractive for designs seeking enhanced performance or supply chain diversification.
Core Conclusion: Selection is not about absolute superiority but precise requirement matching. In the context of supply chain diversification, domestic alternatives like those from VBsemi provide viable backup options and, in some cases like the VBMB19R11S, offer performance advantages in key parameters. This gives engineers greater flexibility and resilience in design trade-offs and cost control. Understanding the specific voltage, current, and loss requirements of your application is essential to selecting the MOSFET that delivers maximum value in your circuit.