MOSFET Selection for High-Voltage Applications: STU5N95K3, STF8N80K5 vs. China Alternatives VBFB19R02S and VBMB18R07S
In high-voltage power designs, selecting a MOSFET that balances voltage withstand capability, conduction loss, and cost is a critical challenge for engineers. This is not a simple part substitution, but a strategic trade-off among performance, reliability, and supply chain stability. This article takes two representative high-voltage MOSFETs, STU5N95K3 and STF8N80K5, as benchmarks, analyzes their design focus and application scenarios, and evaluates their domestic alternative solutions, VBFB19R02S and VBMB18R07S. By clarifying parameter differences and performance orientations, we aim to provide a clear selection guide for your next high-voltage design.
Comparative Analysis: STU5N95K3 (N-channel) vs. VBFB19R02S
Analysis of the Original Model (STU5N95K3) Core:
This is a 950V N-channel MOSFET from STMicroelectronics in a TO-251-3 (IPAK) package. Its design core is to provide robust high-voltage switching in a cost-effective, compact through-hole package. Key advantages are its high drain-source voltage (950V) and a continuous drain current of 4A. The on-resistance is 3.5Ω at 10V gate drive.
Compatibility and Differences of the Domestic Alternative (VBFB19R02S):
VBsemi's VBFB19R02S is a pin-to-pin compatible alternative in a TO-251 package. The main differences are in electrical parameters: VBFB19R02S has a slightly lower voltage rating (900V) but offers a significantly lower on-resistance of 2.7Ω (2700mΩ) at 10V. Its continuous current rating is 2A.
Key Application Areas:
Original Model STU5N95K3: Ideal for applications requiring very high voltage blocking (up to 950V) with moderate current (up to 4A). Typical applications include:
Off-line switchers and SMPS for appliances and industrial systems.
Power factor correction (PFC) stages.
Lighting ballasts and LED drivers.
Alternative Model VBFB19R02S: Suitable for 900V systems where lower conduction loss (due to lower RDS(on)) is prioritized, and the current requirement is within 2A. It offers a performance-efficient alternative for cost-sensitive, high-voltage designs.
Comparative Analysis: STF8N80K5 (N-channel) vs. VBMB18R07S
This comparison focuses on higher-current capability within the 800V range. The original model's design pursues a balance of voltage rating, current handling, and switching performance.
The core advantages of the original model (STF8N80K5) are:
High Voltage & Current: 800V drain-source voltage and 6A continuous current.
Low On-Resistance: 950mΩ at 10V gate drive, contributing to lower conduction losses.
Advanced Technology: Features ST's MDmesh K5 technology for good switching performance and efficiency.
Robust Package: TO-220FP package offers good thermal performance for medium-power applications.
The domestic alternative VBMB18R07S is a "performance-enhanced" choice: It matches the 800V voltage rating but offers superior key parameters: a higher continuous current of 7A and a significantly lower on-resistance of 770mΩ at 10V. This translates to potentially lower temperature rise and higher efficiency.
Key Application Areas:
Original Model STF8N80K5: An excellent choice for efficient medium-power, high-voltage applications. For example:
Higher-power SMPS and off-line converters.
Motor drives for appliances and industrial controls.
Solar inverter auxiliary circuits.
Alternative Model VBMB18R07S: More suitable for upgrade scenarios demanding higher current capability (up to 7A) and lower conduction loss. Ideal for designing more compact or higher-efficiency 800V systems.
Conclusion:
This analysis reveals two distinct selection paths for high-voltage designs:
1. For ultra-high voltage (950V) applications with moderate current, the original STU5N95K3 offers a reliable solution. Its domestic alternative VBFB19R02S provides a compatible option with lower on-resistance for 900V systems where current is below 2A.
2. For 800V applications where current handling and efficiency are critical, the original STF8N80K5 provides a balanced performance. Its domestic alternative VBMB18R07S presents a compelling "performance-enhanced" option with higher current rating and lower RDS(on), suitable for next-generation, higher-efficiency designs.
The core takeaway is that selection depends on precise requirement matching. In the context of supply chain diversification, domestic alternatives like VBFB19R02S and VBMB18R07S not only provide viable backups but also offer performance advantages in specific parameters, giving engineers greater flexibility in design and cost optimization. Understanding each device's design philosophy and parameter implications is key to maximizing its value in your circuit.