With the advancement of collaborative robotics and the demand for agile mobile platforms, bipedal mobile collaborative robots have become core equipment for complex interaction and navigation tasks. The joint actuator drive and power management systems, serving as the "muscles and nervous system" of the entire unit, provide precise power delivery and control for key loads such as joint motors, servo drives, and sensor modules. The selection of power MOSFETs directly determines system dynamic response, efficiency, power density, and operational reliability. Addressing the stringent requirements of mobile robots for high torque-density, energy efficiency, compactness, and safety, this article focuses on scenario-based adaptation to develop a practical and optimized MOSFET selection strategy.
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 matching with the demanding operating conditions of a mobile robot:
Sufficient Voltage Margin: For motor drives powered by battery packs (e.g., 24V, 48V, or higher), reserve a rated voltage withstand margin of ≥60-80% to handle regenerative braking voltage spikes and bus fluctuations. For example, prioritize devices with ≥80V for a 48V bus.
Prioritize Low Loss & Fast Switching: Prioritize devices with ultra-low Rds(on) (minimizing conduction loss in high-current paths), and low Qg/Qgd (enabling fast switching for high-frequency PWM, crucial for dynamic motor control and torque ripple reduction).
Package Matching for High Density: Choose DFN/QFN packages with excellent thermal performance and low parasitic inductance for high-power joint actuators. Select compact packages like SOT/TSSOP for medium/small power management and sensor loads, maximizing power density in a confined space.
Robustness & Reliability: Meet requirements for shock, vibration, and continuous dynamic operation. Focus on high avalanche energy rating, strong ESD protection, and a wide junction temperature range, adapting to unpredictable real-world environments.
(B) Scenario Adaptation Logic: Categorization by Load Type
Divide loads into three core scenarios based on function and power level: First, Joint Actuator Motor Drive (Power & Motion Core), requiring very high-current, high-efficiency, and fast-switching capabilities for precise torque control. Second, Centralized Power Distribution & Safety Switching (System Management), requiring robust high-side switches for safe power routing and fault isolation. Third, Auxiliary & Sensor Module Power (Perception & Control Support), requiring efficient, compact load switches for numerous low-to-medium power subsystems.
II. Detailed MOSFET Selection Scheme by Scenario
(A) Scenario 1: Joint Actuator Motor Drive (100W-500W+) – High-Dynamic Power Device
Joint motors (typically BLDC/PMSM) require handling large continuous phase currents and high peak currents during acceleration/deceleration, demanding ultra-low loss and fast switching for efficient, responsive, and smooth motion control.
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 48V battery systems. The 51A continuous current rating handles significant power. The DFN8 package offers low thermal resistance and extremely low parasitic inductance, critical for minimizing switching overshoot and heat generation in high-frequency inverter bridges.
Adaptation Value: Dramatically reduces conduction loss in motor phase paths. Enables the use of high PWM frequencies (50kHz-100kHz+) for superior current loop bandwidth, leading to lower torque ripple, quieter acoustic operation, and enhanced joint position accuracy. The high efficiency directly extends battery operational lifetime.
Selection Notes: Match device rating to motor peak phase current with ≥50% margin. The DFN package requires a substantial PCB copper pour (≥250mm² per device) paired with thermal vias for effective heat sinking. Must be paired with a high-performance gate driver IC (e.g., with 2A+ source/sink capability).
(B) Scenario 2: Centralized Power Distribution & Safety Switching – System Management Device
This involves high-side switching of main power rails to various subsystems (e.g., motor driver boards, computing unit). It requires high voltage blocking capability, moderate current handling, and often P-channel configuration for simplified gate driving in high-side applications, ensuring safe power-on sequencing and fault isolation.
Recommended Model: VB2101K (P-MOS, -100V, -1.5A, SOT23-3)
Parameter Advantages: High -100V drain-source voltage rating is excellent for safely switching 24V or 48V main buses with substantial margin for transients. The compact SOT23-3 package saves critical board space. A Vth of -2V allows for relatively straightforward driving from logic-level signals when using a charge pump or level translator.
Adaptation Value: Enables intelligent and independent power domain control for different robot sections (e.g., shutting down an arm's power while the base remains operational). Its high voltage rating enhances system robustness against load dump events. The small size allows integration into dense power management units (PMUs).
Selection Notes: Ensure the continuous load current is well below the 1.5A rating, considering derating. Gate drive must be properly designed to fully enhance the P-MOSFET. A series gate resistor (e.g., 10Ω-47Ω) is recommended to damp ringing.
(C) Scenario 3: Auxiliary & Sensor Module Power – Perception & Control Support Device
These loads (LiDAR, cameras, IMU, servo controllers, communication modules) are numerous, have varied power needs (1W-20W), and require clean, digitally controlled power switching for system low-power modes and functional safety.
Recommended Model: VBC7N3010 (N-MOS, 30V, 8.5A, TSSOP8)
Parameter Advantages: 30V rating is perfect for sub-rails like 5V, 12V, or 24V. Low Rds(on) of 12mΩ at 10V minimizes voltage drop and power loss. The 8.5A current rating covers a wide range of auxiliary loads. The TSSOP8 package offers a good balance of current handling, heat dissipation capability (through an exposed pad), and footprint efficiency.
Adaptation Value: Provides an efficient and compact solution for local power switching of sensor clusters or peripheral boards. The low Rds(on) is key for powering loads like small servo drives or camera modules without significant supply sag. Allows the main computer to power-cycle peripherals for fault recovery or energy saving.
Selection Notes: Verify load inrush currents, especially for capacitive modules. A small gate resistor (22Ω-100Ω) is advised. The exposed pad should be soldered to a corresponding PCB pad with thermal vias for best thermal performance.
III. System-Level Design Implementation Points
(A) Drive Circuit Design: Matching Device Characteristics
VBGQF1810: Must be driven by a dedicated half-bridge or three-phase gate driver IC (e.g., DRV8353, ISL8240M) capable of high peak currents (>2A) to achieve fast switching. Minimize power loop and gate loop inductance in the PCB layout.
VB2101K: For high-side switching, use a dedicated high-side driver, a charge pump circuit, or an NPN/PNP level-shifter stage to ensure sufficient Vgs for full enhancement. Include a pull-down resistor on the gate.
VBC7N3010: Can often be driven directly by a microcontroller GPIO for low-frequency on/off control. For faster switching or if the MCU drive is weak, use a small MOSFET driver buffer (e.g., SN74LVC1G17). Implement RC filtering on the gate if noise immunity is a concern.
(B) Thermal Management Design: Tiered Heat Dissipation
VBGQF1810 (Critical): Requires aggressive thermal design. Use maximum possible copper area on all layers connected via dense thermal vias. Consider a thermally conductive pad to transfer heat to the robot's internal chassis or a dedicated heatsink. Active monitoring of heatsink temperature is recommended.
VB2101K (Low): The SOT23-3 package relies on the PCB traces for heat dissipation. Ensure connected traces are sufficiently wide.
VBC7N3010 (Medium): The exposed pad is crucial. Solder it to a dedicated thermal pad on the PCB (≥30mm²) with multiple thermal vias to internal ground planes for heat spreading.
(C) EMC and Reliability Assurance
EMC Suppression
VBGQF1810: Use low-ESR/ESL ceramic capacitors (e.g., 100nF X7R) very close to the drain-source pins of each MOSFET in the bridge. A snubber circuit (RC) across the motor terminals may be needed to damp high-frequency ringing.
VB2101K/VBC7N3010: Add a small bypass capacitor (0.1µF) close to the load side of the switch. For inductive loads (e.g., small solenoids), include a flyback diode.
Reliability Protection
Derating Design: Apply conservative derating (e.g., 60-70% of max current rating, 50% of voltage rating) for all devices considering the harsh mobile environment.
Overcurrent Protection: Implement hardware-based current sensing (shunt resistor + amplifier/comparator) in all motor phases and on main power rails. The gate driver IC for VBGQF1810 should have DESAT or shunt-based protection.
ESD/Surge Protection: Use TVS diodes at all external connectors (sensor, power input). Gate protection diodes or resistors are advisable for switches connected to external modules.
IV. Scheme Core Value and Optimization Suggestions
(A) Core Value
High Dynamic Performance: The use of VBGQF1810 enables high-bandwidth motor control, resulting in smoother, more responsive, and more stable robot locomotion.
Enhanced System Safety & Management: VB2101K provides a robust and simple building block for implementing safe power architecture with isolation capabilities.
Optimized Power Density & Efficiency: The combination of high-performance DFN and space-saving SOT/TSSOP packages maximizes functionality within the strict volume and weight constraints of a mobile robot, while low Rds(on) devices minimize wasted energy.
(B) Optimization Suggestions
Power Scaling: For larger robots with joint motors exceeding 1kW, consider higher-current variants like VBGQF11307 or parallel configuration of VBGQF1810. For the main battery disconnect switch, a higher-current P-MOS or a load switch IC might be preferable to VB2101K.
Integration Upgrade: For highly integrated joint modules, consider using pre-assembled three-phase IPM (Intelligent Power Modules) that include drivers and protection. For dense sensor hubs, multi-channel load switch ICs can replace several discrete VBC7N3010 devices.
Special Scenarios: For robots operating in extreme environments, seek automotive-grade (AEC-Q101) qualified versions of the selected MOSFETs. For ultra-low quiescent power needs in sleep modes, select MOSFETs with very low leakage current.
Conclusion
Power MOSFET selection is central to achieving high dynamic performance, efficiency, safety, and compactness in bipedal mobile collaborative robots. This scenario-based scheme provides comprehensive technical guidance for R&D through precise load matching and system-level design tailored to the unique demands of mobile robotics. Future exploration can focus on wide-bandgap (GaN) devices for even higher efficiency and switching speed, and advanced power module integration, aiding in the development of next-generation agile and enduring robotic platforms.

Detailed Topology Diagrams