In high-voltage power conversion and switching applications, selecting a MOSFET that balances voltage rating, switching performance, and cost is a critical engineering decision. This goes beyond simple part substitution—it requires careful consideration of efficiency, ruggedness, and supply chain stability. This article takes two representative high-voltage MOSFETs, FDA24N50F (N-channel) and FQD3N60CTM-WS (N-channel), as benchmarks, analyzes their design focus and application scenarios, and evaluates two domestic alternative solutions, VBPB16R20S and VBE16R02S. By clarifying parameter differences and performance orientations, we provide a clear selection guide to help you find the most suitable power switching solution for your next high-voltage design.
Comparative Analysis: FDA24N50F (N-channel) vs. VBPB16R20S
Analysis of the Original Model (FDA24N50F) Core:
This is a 500V N-channel UniFET™ MOSFET from onsemi, in a TO-3PN package. Its design core is based on planar stripe and DMOS technology, aiming to provide lower conduction resistance, improved switching performance, and higher avalanche energy capability. A key advantage is its enhanced body diode with fast reverse recovery (trr < 100ns) and high reverse dv/dt immunity (15V/ns), which can improve system reliability in applications like PFC and switching power supplies. It features a continuous drain current of 24A and an on-resistance of 166mΩ @ 10V, 12A.
Compatibility and Differences of the Domestic Alternative (VBPB16R20S):
VBsemi's VBPB16R20S is offered in a TO3P package and serves as a functional alternative for similar high-voltage applications. The main parameter differences are: VBPB16R20S has a higher voltage rating (600V vs. 500V), but a lower continuous current rating (20A vs. 24A) and a slightly higher on-resistance (190mΩ @ 10V vs. 166mΩ).
Key Application Areas:
Original Model FDA24N50F: Its combination of 500V rating, 24A current, optimized switching, and robust body diode makes it well-suited for:
Power Factor Correction (PFC) circuits.
Switching power converters for FPD TV power supplies, ATX power supplies.
Electronic lamp ballasts and other medium-power off-line applications.
Alternative Model VBPB16R20S: More suitable for applications requiring a 600V voltage margin with current demands around 20A, such as certain SMPS designs or motor drives where the higher voltage rating is prioritized.
Comparative Analysis: FQD3N60CTM-WS (N-channel) vs. VBE16R02S
This comparison focuses on a lower-current, high-voltage switch where package size and cost are often significant factors.
Analysis of the Original Model (FQD3N60CTM-WS) Core:
This is a 600V, 2.4A N-channel MOSFET from onsemi in a compact DPAK-3 package. Its design pursues a cost-effective solution for lower-power high-voltage switching. It offers a standard on-resistance of 3.4Ω @ 10V, suitable for applications like auxiliary power supplies or signal switching where currents are modest.
Compatibility and Differences of the Domestic Alternative (VBE16R02S):
VBsemi's VBE16R02S comes in a TO252 package and provides a pin-to-pin compatible alternative for the DPAK footprint. It matches the 600V voltage rating and offers a similar continuous current of 2A. Its on-resistance is specified at 2300mΩ @ 10V.
Key Application Areas:
Original Model FQD3N60CTM-WS: Its low-current, high-voltage profile in a small package makes it ideal for:
Auxiliary/standby power sections in switch-mode power supplies (SMPS).
Low-power offline converters or snubber circuits.
General-purpose high-voltage switching where current demand is below 2.5A.
Alternative Model VBE16R02S: Serves as a direct replacement in applications requiring 600V withstand voltage and around 2A current capability, offering a supply chain alternative with comparable performance in the same circuit footprint.
Conclusion
In summary, this analysis reveals two distinct selection paths for high-voltage applications:
For medium-power applications (like PFC or main SMPS switches) around 500V, the original model FDA24N50F, with its 24A current capability, low 166mΩ on-resistance, and optimized fast-recovery body diode, presents strong advantages for efficiency and reliability. Its domestic alternative VBPB16R20S offers a higher 600V rating and similar package, making it a viable option where voltage margin is critical, albeit with a slight trade-off in current and conduction loss.
For lower-power, high-voltage switching tasks (like auxiliary power), the original model FQD3N60CTM-WS in the DPAK package provides a compact, cost-effective solution. Its domestic alternative VBE16R02S in TO252 offers direct footprint compatibility and equivalent voltage/current ratings, serving as a practical alternative for supply chain diversification.
The core takeaway is that selection hinges on precise requirement matching. In the context of supply chain diversification, domestic alternatives like VBPB16R20S and VBE16R02S not only provide feasible backup options but also offer engineers greater flexibility in design trade-offs and cost control for high-voltage designs. Understanding each device's parameter implications is key to maximizing its value in the circuit.