With the advancement of smart home integration and the rising demand for energy-efficient appliances, smart washing machines have become central to modern household convenience. The power supply and motor drive systems, acting as the "heart and actuators" of the unit, provide precise power conversion and control for critical loads such as the main drive motor, water inlet/outlet valves, pumps, and auxiliary control circuits. The selection of power MOSFETs directly dictates system efficiency, noise performance, power density, and long-term reliability. Addressing the stringent requirements of washing machines for high torque, low acoustic noise, water-resistant reliability, and high integration, this article develops a practical and optimized MOSFET selection strategy through scenario-based adaptation.
I. Core Selection Principles and Scenario Adaptation Logic
(A) Core Selection Principles: Four-Dimensional Collaborative Adaptation
MOSFET selection requires coordinated adaptation across four dimensions—voltage, loss, package, and reliability—ensuring precise alignment with system operating conditions:
Sufficient Voltage Margin: For common bus voltages (12V, 24V, or direct rectified ~325V DC for inverter drives), maintain a rated voltage margin ≥50% to withstand inductive spikes and line transients. For example, for a 24V auxiliary system, prefer devices rated ≥40V.
Prioritize Low Loss: Focus on low Rds(on) (minimizing conduction loss) and low Qg/Coss (minimizing switching loss), adapting to frequent start-stop cycles and variable load profiles to boost energy efficiency class and reduce thermal stress.
Package Matching: Opt for DFN packages with superior thermal performance and low parasitic inductance for high-current motor drives. Choose compact packages like TSSOP, SOT, or SC for valve, pump, and auxiliary control, balancing space constraints and heat dissipation needs.
Reliability Redundancy: Meet demands for moisture resistance, vibration tolerance, and long operational life. Prioritize devices with robust ESD protection, wide junction temperature range (e.g., -55°C ~ 150°C), and suitability for humid environments.
(B) Scenario Adaptation Logic: Categorization by Load Type
Divide loads into three core scenarios: First, the Main Motor Drive (Torque Core), requiring high-current, high-efficiency switching for BLDC or inverter-driven motors. Second, Auxiliary Actuator Control (Functional Execution), including solenoid valves, drain pumps, and door locks, requiring medium-current switching with fast response and reliable on/off control. Third, Multi-Channel & Low-Power Control (System Management), involving multi-path switching for sensors, indicators, or communication modules, demanding high integration and low quiescent power.
II. Detailed MOSFET Selection Scheme by Scenario
(A) Scenario 1: Main Motor Drive (BLDC/Inverter, 200W-500W) – Power Core Device
The main drive motor requires handling high continuous currents and peak currents during spin cycles or startup, demanding high efficiency and low switching loss for smooth, quiet operation.
Recommended Model: VBGQF1810 (N-MOS, 80V, 51A, DFN8(3x3))
Parameter Advantages: SGT technology achieves an ultra-low Rds(on) of 9.5mΩ at 10V. The 80V rating provides ample margin for 24V or higher voltage bus systems. Continuous current of 51A (with high peak capability) suits typical washing machine motor demands. The DFN8 package offers excellent thermal resistance and low parasitic inductance, crucial for high-frequency PWM motor control.
Adaptation Value: Drastically reduces conduction loss. For a 24V/300W motor drive, conduction losses are minimal, supporting inverter efficiency >95%. Enables high-frequency PWM (typically 16kHz-20kHz) for acoustic noise reduction, contributing to quieter operation. The high voltage rating safeguards against back-EMF spikes.
Selection Notes: Confirm motor power rating, bus voltage, and worst-case peak current. Ensure a PCB thermal pad ≥200mm² with thermal vias for the DFN package. Pair with dedicated motor driver ICs (e.g., IR2136, FD2106) featuring integrated protection.
(B) Scenario 2: High-Side Switching & Complementary Drive – System Flexibility Device
Applications such as high-side switching for valves or forming half-bridges for pump control require P-Channel MOSFETs with low Rds(on) and good current capability in a compact footprint.
Recommended Model: VBQF2309 (P-MOS, -30V, -45A, DFN8(3x3))
Parameter Advantages: Very low Rds(on) of 11mΩ at 10V for a P-MOS device, minimizing conduction loss. High continuous current (-45A) handles solenoid valves or small pumps effortlessly. The -30V rating is suitable for 12V/24V systems. DFN8 package ensures good thermal performance.
Adaptation Value: Enables efficient high-side switching without needing a charge pump, simplifying drive circuitry. Can be used in complementary pairs with N-MOSFETs for bidirectional pump control or H-bridge configurations. Its low loss contributes to lower system thermal load.
Selection Notes: Ensure gate drive voltage (Vgs) is sufficiently negative (e.g., -10V) for full enhancement. Provide adequate gate drive strength. Implement proper heatsinking via PCB copper pour for continuous high-current operation.
(C) Scenario 3: Multi-Channel Auxiliary Actuator Control – Integrated Control Device
Controlling multiple auxiliary loads like water inlet valves, drain valves, circulation pumps, or door lock actuators requires compact, multi-channel switches with independent control and protection.
Recommended Model: VBC6P2216 (Dual P-MOS, -20V, -7.5A/Ch, TSSOP8)
Parameter Advantages: TSSOP8 package integrates two P-MOSFETs, saving over 50% PCB area compared to discrete solutions. Low Rds(on) of 13mΩ per channel at 10V minimizes voltage drop. The -20V rating fits 12V systems comfortably. Each channel handles -7.5A, sufficient for most valves and small pumps.
Adaptation Value: Allows independent and simultaneous control of two auxiliary loads (e.g., hot and cold water valves). Facilitates smart sequencing and interlocking. The integrated dual design simplifies PCB layout and reduces component count, enhancing reliability.
Selection Notes: Verify individual load current and inrush characteristics. Use simple NPN or level-shifter circuits for gate drive from MCU (3.3V/5V). Consider adding flyback diodes for inductive loads (valves, pumps). Ensure symmetric PCB copper allocation under the package for heat dissipation.
III. System-Level Design Implementation Points
(A) Drive Circuit Design: Matching Device Characteristics
VBGQF1810: Pair with dedicated gate driver ICs (source/sink current ≥2A) for the motor inverter bridge. Minimize high-current loop area in PCB layout. Use gate resistors (e.g., 4.7Ω-22Ω) to control switching speed and reduce EMI.
VBQF2309: For high-side drive, use a P-MOS driver or an NPN level translator. Ensure a stable and low-impedance negative voltage rail (relative to source) for gate turn-on.
VBC6P2216: Can be driven directly from MCU GPIOs for slower switching via a series resistor (100Ω-1kΩ). For faster switching, use a buffer. Implement individual pull-up resistors (10kΩ-100kΩ) on each gate to ensure defined off-state.
(B) Thermal Management Design: Tiered Heat Dissipation
VBGQF1810 (Main Motor Drive): Primary thermal focus. Use a large top/bottom copper pour (≥300mm² recommended), 2oz copper weight, and multiple thermal vias under the DFN pad. Consider attaching a heatsink to the PCB area or using thermal interface material to the chassis if power exceeds 300W.
VBQF2309 (High-Side Switch): Allocate a substantial copper area (≥150mm²) connected to the drain pins (which are often the thermal pad). Thermal vias are essential.
VBC6P2216 (Auxiliary Control): Provide symmetrical copper pours of ≥50mm² per channel under the TSSOP8 package. Thermal vias help if loads are imbalanced or ambient temperature is high.
General: Position high-power MOSFETs away from moisture-prone areas. Ensure overall machine ventilation aids in convective cooling.
(C) EMC and Reliability Assurance
EMC Suppression:
VBGQF1810: Place snubber circuits (RC) across motor phases if needed. Use common-mode chokes on motor cables. Add bypass capacitors (100nF ceramic + 10uF electrolytic) near the drain-source connections.
For all controls: Add ferrite beads in series with gate drive lines near the MOSFET. Use TVS diodes across inductive loads (valves, pump motors).
PCB Layout: Implement strict separation of power, motor drive, and low-voltage digital/analog sections. Use a solid ground plane.
Reliability Protection:
Derating Design: Operate MOSFETs at ≤70-80% of their rated current and voltage under worst-case temperature conditions.
Overcurrent Protection: Implement shunt resistors or current-sense ICs in the motor phase paths and major auxiliary load paths. Use driver ICs with built-in current limiting.
Overvoltage/ESD Protection: Place TVS diodes (e.g., SMCJ24A) at the power input. Use gate-source TVS (e.g., SMF6.5CA) for sensitive gate pins. Add varistors at AC inlet.
Moisture & Contamination: Conformal coating can be applied to control boards, avoiding thermal pads. Ensure seals and gaskets protect the control compartment.
IV. Scheme Core Value and Optimization Suggestions
(A) Core Value
High Efficiency & Low Noise: The selected low-Rds(on) MOSFETs, particularly for the motor drive, significantly reduce energy loss, helping achieve high energy efficiency ratings (e.g., EU Energy Label A+++). High-frequency PWM capability contributes to lower acoustic noise.
High Integration & Reliability: Using dual MOSFETs (VBC6P2216) and compact packages saves valuable PCB space for other features. The robust voltage ratings and package choices enhance system reliability in demanding laundry environments.
Cost-Effective Performance: The selected devices offer an optimal balance between advanced performance (SGT, low Rds(on)) and cost-effectiveness for mass-produced consumer appliances.
(B) Optimization Suggestions
Higher Power Motors: For washing machines with direct-drive motors exceeding 500W, consider higher voltage/current variants like VBGP11307 (120V/110A) or parallel operation of VBGQF1810.
Low-Voltage Auxiliary Systems: For 5V-controlled valves or sensors, consider lower Vth devices like VBKB4265 (Vth=-0.8V, -3.5A, SC70-8) for easier direct MCU control.
More Integrated Solutions: For complex auxiliary control banks, explore multi-channel load switch ICs that integrate protection features.
Enhanced Safety: For critical safety functions like door locking, implement redundant switching or use latching circuits alongside the MOSFET control.
Conclusion
Strategic MOSFET selection is pivotal in realizing the efficiency, quietness, intelligence, and durability expected of modern smart washing machines. This scenario-adapted strategy, centering on the high-performance VBGQF1810 for the motor, the flexible VBQF2309 for high-side/pump control, and the integrated VBC6P2216 for auxiliary actuators, provides a comprehensive technical foundation. Future development can explore integrated motor driver modules (IPMs) and wide-bandgap (GaN) devices for even higher power density and efficiency, driving the evolution of next-generation laundry appliances.

Detailed Topology Diagrams