MOSFET Selection for High-Voltage Power Applications: STF17N80K5, STFU13N80K5 vs. China Alternatives VBMB18R15S, VBMB18R11S
In high-voltage power conversion and motor drive designs, selecting a MOSFET that balances high blocking voltage, low conduction loss, and robust thermal performance is a critical engineering challenge. This goes beyond simple part substitution, requiring careful trade-offs among voltage rating, on-resistance, current capability, package, and supply chain security. This article takes two representative 800V N-channel MOSFETs from STMicroelectronics—STF17N80K5 (TO-220FP) and STFU13N80K5 (TO-220)—as benchmarks. It delves into their design cores and application contexts, while providing a comparative evaluation of two domestic alternative solutions: VBMB18R15S and VBMB18R11S from VBsemi. By clarifying their parametric differences and performance orientations, we aim to offer a clear selection guide to help you find the most suitable high-voltage switching solution in your next design.
Comparative Analysis: STF17N80K5 (TO-220FP) vs. VBMB18R15S
Analysis of the Original Model (STF17N80K5) Core:
This is an 800V N-channel MOSFET from ST, utilizing the MDmesh K5 superjunction technology and packaged in TO-220FP (fully isolated). Its design core is to achieve high efficiency and reliability in high-voltage applications. Key advantages include: a high voltage rating of 800V, a continuous drain current (Id) of 14A, and a typical on-resistance (RDS(on)) of 0.29 Ohm (340mΩ @10V, 7A per datasheet). The TO-220FP package offers good thermal performance with electrical isolation.
Compatibility and Differences of the Domestic Alternative (VBMB18R15S):
VBsemi's VBMB18R15S is offered in a standard TO-220F package and serves as a functional pin-to-pin compatible alternative. The main parametric differences are: it matches the 800V voltage rating and offers a slightly higher continuous current rating of 15A. However, its on-resistance is specified as 370mΩ @10V, which is moderately higher than the original ST part's typical value.
Key Application Areas:
Original Model STF17N80K5: Its combination of 800V rating, 14A current, and low RDS(on) makes it well-suited for high-efficiency, medium-power off-line applications.
Switch Mode Power Supplies (SMPS): PFC (Power Factor Correction) stages, flyback, or forward converters in industrial/consumer AC-DC power supplies.
Motor Drives: Inverter stages for driving fans, pumps, or appliances.
Lighting: High-voltage LED drivers or ballast control.
Alternative Model VBMB18R15S: Suitable as a direct replacement in the same applications where the slightly higher RDS(on) is acceptable within the system's loss budget, while offering a marginal current rating advantage and potential cost/supply chain benefits.
Comparative Analysis: STFU13N80K5 (TO-220) vs. VBMB18R11S
This comparison focuses on another 800V MOSFET from ST in a standard TO-220 package, where the design emphasis is on a cost-effective balance for high-voltage switching.
Analysis of the Original Model (STFU13N80K5) Core:
This model also features ST's MDmesh K5 technology in a standard TO-220-3 package. Its core advantages are: the high 800V drain-source voltage, a continuous current of 12A, and a specified on-resistance of 450mΩ @10V. The standard TO-220 package provides a classic, cost-effective solution with good thermal dissipation when mounted on a heatsink.
Compatibility and Differences of the Domestic Alternative (VBMB18R11S):
VBsemi's VBMB18R11S, in a TO-220F package, is a pin-to-pin compatible alternative. The parameters are closely matched: same 800V rating, a slightly lower continuous current of 11A, and a specified on-resistance of 480mΩ @10V. This makes it a near-equivalent performance substitute.
Key Application Areas:
Original Model STFU13N80K5: Ideal for cost-sensitive high-voltage applications requiring reliable 800V blocking capability.
Industrial Controls: Auxiliary power supplies, relay/solenoid drivers.
Consumer Durables: Power management in appliances like air conditioners or washing machines.
Renewable Energy: Low-power sections of solar inverters or battery management systems.
Alternative Model VBMB18R11S: Serves as a viable domestic alternative for the same application spaces, offering a reliable switching solution with comparable electrical characteristics, aiding in design redundancy and supply chain diversification.
Summary and Selection Paths:
This analysis reveals two clear substitution paths for 800V MOSFETs:
1. For the TO-220FP package (STF17N80K5): The original model offers excellent performance with its low typical RDS(on) and 14A current. The domestic alternative VBMB18R15S provides a compatible package, a matched 800V rating, and a slightly higher 15A current rating, though with a moderately higher specified RDS(on). It is a strong candidate for replacement where the conduction loss difference is manageable.
2. For the standard TO-220 package (STFU13N80K5): The original model is a robust, cost-effective choice. The domestic alternative VBMB18R11S offers nearly identical key specifications (800V, ~11A, ~480mΩ), making it a highly direct and practical substitute for reducing supply chain dependence.
Core Conclusion: Selection is not about absolute superiority but precise requirement matching. In the context of supply chain diversification, these domestic alternatives (VBMB18R15S and VBMB18R11S) provide not just feasible backups but also competitive parametric offerings. They grant engineers greater flexibility and resilience in design trade-offs, cost control, and procurement strategy. A deep understanding of each device's specifications and application context is key to unlocking its full value in the circuit.