With the rapid development of urban air mobility and low-altitude tourism, electric Vertical Take-Off and Landing (eVTOL) aircraft for scenic area sightseeing have become a forefront application, demanding extreme reliability, safety, and power density. The propulsion, power distribution, and critical system control modules, serving as the "heart and nerves" of the aircraft, require precise and robust power switching. The selection of power MOSFETs is pivotal in determining system efficiency, weight, thermal management, and operational safety. Addressing the stringent requirements of eVTOL for high power-to-weight ratio, fault tolerance, and harsh environment operation, this article develops a scenario-based, optimized MOSFET selection strategy.
I. Core Selection Principles and Scenario Adaptation Logic
(A) Core Selection Principles: Multi-Dimensional Optimization for Aviation
MOSFET selection must balance voltage rating, conduction/switching losses, package power density/thermal performance, and aviation-grade reliability under varying environmental stresses.
Voltage with High Derating: For high-voltage propulsion buses (e.g., 400V DC), select devices with sufficient margin (≥50-100%) to handle regenerative braking spikes and transients. For low-voltage avionics (e.g., 12V/24V), ensure margin for surge events.
Ultra-Low Loss Priority: Minimize Rds(on) and gate charge (Qg) to reduce conduction and switching losses, directly improving flight time, reducing heat sink weight, and enhancing overall efficiency.
Package for Power Density & Cooling: Prioritize packages with excellent thermal impedance (RthJC) and low parasitic inductance for propulsion. Use compact, lightweight surface-mount packages for distributed systems to save weight and space.
Extended Reliability & Ruggedness: Devices must operate across wide temperature ranges (-55°C to 175°C), have high ESD robustness, and demonstrate long-term stability under vibration and humidity for mission-critical safety.
(B) Scenario Adaptation Logic: Categorization by Flight-Critical Function
Divide applications into three core scenarios: First, High-Voltage Propulsion Motor Drive (thrust core), requiring very high current, high voltage, and ultra-low loss. Second, Low-Voltage Auxiliary & Avionics Power Distribution (system support), requiring efficient switching, compact size, and control compatibility. Third, Safety-Critical System & Isolation Control (redundancy & protection), requiring multi-channel integration, reliable fault isolation, and fail-safe operation.
II. Detailed MOSFET Selection Scheme by Scenario
(A) Scenario 1: High-Voltage Propulsion Motor Drive (400V+ Bus) – Thrust Core Device
eVTOL lift and cruise motors demand high voltage blocking, high continuous/peak current, and minimal loss for maximum range and power-to-weight ratio.
Recommended Model: VBMB15R24S (Single-N, 500V, 24A, TO220F)
Parameter Advantages: Super-Junction Multi-EPI technology achieves an extremely low Rds(on) of 120mΩ at 10V. 500V VDS provides solid margin for 400V bus systems. 24A continuous current rating supports high-power motor phases. TO220F package offers good thermal performance with isolated tab.
Adaptation Value: Dramatically reduces conduction loss in inverter bridges. Enables high-efficiency (>98%) motor drives, directly extending flight time. The 500V rating ensures robustness against high-voltage transients during switching and regeneration.
Selection Notes: Must be used with qualified gate drivers (e.g., isolated drivers like Si8239) with sufficient drive current. Implement strict derating (e.g., current derated at high case temperatures). Requires substantial heatsinking, potentially coupled with liquid cooling plates in high-power designs.
(B) Scenario 2: Low-Voltage Auxiliary & Avionics Power Distribution (12V/24V Bus) – System Support Device
Avionics, sensors, lighting, and communication modules require reliable, efficient, and compact load switches or DC-DC converter switches.
Recommended Model: VBA1630 (Single-N, 60V, 7.6A, SOP8)
Parameter Advantages: 60V VDS offers high margin for 24V/28V aircraft buses. Very low Rds(on) of 25mΩ at 10V minimizes voltage drop and loss. Low Vth of 1.7V allows direct drive from 3.3V/5V MCUs. SOP8 package provides a good balance of power handling and PCB space savings.
Adaptation Value: Ideal for point-of-load switching and synchronous rectification in distributed DC-DC converters. High efficiency reduces thermal stress in enclosed avionics bays. Saves weight and space compared to bulkier packages.
Selection Notes: Ensure load current is within safe operating area with PCB copper heat spreading. Add gate resistors to control switching speed and EMI. For high-reliability zones, consider parallel use for current sharing.
(C) Scenario 3: Safety-Critical System & Isolation Control (Redundancy Management) – Protection & Switching Device
Battery management system (BMS) isolation, redundant bus tie switching, and critical actuator control require integrated, reliable switching with fault isolation capability.
Recommended Model: VBTA4250N (Dual-P+P, -20V, -0.5A per channel, SC75-6)
Parameter Advantages: Ultra-compact SC75-6 package integrates two P-MOSFETs, saving over 70% board space compared to discrete devices—critical for redundant circuit layouts. -20V VDS is suitable for low-side isolation switching on 12V rails. Very low Vth of -0.6V enables easy drive from low-voltage logic.
Adaptation Value: Enables compact design of redundant power path controllers and isolation switches in BMS or dual-bus systems. Allows independent control of two safety-critical loads (e.g., dual valves, fans) with physical isolation on a single chip, enhancing system redundancy and fault containment.
Selection Notes: Confirm application voltage and current are well within ratings. Requires careful level-shift drive circuit for high-side P-MOSFET control. The tiny package demands precise PCB assembly and adequate thermal relief in the layout.
III. System-Level Design Implementation Points
(A) Drive Circuit Design: Matched to Device and Environment
VBMB15R24S: Use high-speed, isolated gate driver ICs with negative voltage turn-off capability to prevent parasitic turn-on. Keep gate loop inductance minimal. Implement desaturation detection for short-circuit protection.
VBA1630: Can be driven directly by MCU GPIO for low-frequency switching. For higher frequencies, use a dedicated driver buffer. Incorporate TVS diodes on the gate for in-flight ESD protection.
VBTA4250N: Utilize dual, independent gate drive circuits, possibly with integrated logic level translators. Include pull-up resistors to ensure defined off-state.
(B) Thermal Management Design: Weight-Efficient Cooling
VBMB15R24S: Primary thermal management focus. Mount on a thick, flat heatsink (possibly liquid-cooled). Use thermal interface material with high conductivity. Extensive PCB copper pour with thermal vias is mandatory.
VBA1630: Rely on PCB copper plane (≥100mm² per device) for heat dissipation. Positioning near board edges or airflow paths in the bay is beneficial.
VBTA4250N: Ensure the small package has sufficient thermal relief copper connected to its pins to prevent local overheating.
Overall: Leverage the aircraft's inherent cooling airflow (ram air) for heatsinks. Conduct thermal analysis at maximum ambient temperature (e.g., 40°C+ ground operation).
(C) EMC and Reliability Assurance for Airborne Systems
EMC Suppression:
VBMB15R24S: Implement snubber circuits across drain-source. Use shielded cables for motor connections. Incorporate common-mode chokes and X/Y capacitors at inverter input/output.
VBA1630/VBTA4250N: Use ferrite beads in series with load/power lines. Employ proper power plane decoupling with low-ESR capacitors.
General: Strict PCB zoning (high-power, low-power, digital). Shield sensitive analog sections.
Reliability Protection:
Derating: Apply stringent derating rules per aerospace guidelines (e.g., voltage ≤70%, current ≤50% at max junction temperature).
Fault Protection: Design comprehensive overcurrent (shunt + comparator), overtemperature (NTC sensors), and overvoltage (TVS/varistor) protection for all critical paths.
Environmental Robustness: Conformal coating may be required. Select components with operational temperature ranges exceeding system requirements. Use lock-wire or adhesive on high-vibration area connectors.
IV. Scheme Core Value and Optimization Suggestions
(A) Core Value
Optimized Power-to-Weight Ratio: The combination of high-efficiency SJ-MOSFETs and compact load switches minimizes losses and cooling system weight, directly benefiting payload and range.
Enhanced Safety through Redundancy: The integration of dual MOSFETs enables compact, reliable redundant circuit designs, improving system fault tolerance.
Balanced Performance and Cost: Utilizing mature, high-volume proven technologies (Trench, SJ) ensures reliability and supply chain stability for scalable production.
(B) Optimization Suggestions
Higher Power Propulsion: For larger eVTOLs with 600V+ buses, consider devices from the same family with higher voltage ratings (e.g., 650V-700V variants like VBMB165R16).
Higher Current Auxiliary Loads: For higher power avionics (e.g., heaters, gimbals), use higher-current variants in D²PAK or TO-252 packages (e.g., VBE1337 for 30V/15A needs).
Extreme Environment Operation: For applications with extreme cold-start requirements, select variants with lower Vth. For high-vibration areas, consider additional mechanical securing of through-hole packages.
Integration Trend: Future designs should evaluate intelligent power modules (IPMs) for propulsion to further reduce size and improve reliability.

Detailed Scenario Topology Diagrams