Against the backdrop of the rapid expansion of flexible automation, collaborative robot (cobot) leasing services, as a core enabler of accessible and on-demand productivity, see their value proposition directly influenced by the performance and reliability of the cobots themselves. The internal power management and motor drive systems act as the cobot's "muscles and nerves," responsible for precise motion control, efficient energy utilization, and ensuring intrinsic safety during human-robot interaction. The selection of power semiconductors profoundly impacts system efficiency, torque density, thermal management, and operational safety. This article, targeting the demanding application scenario of leased cobots—characterized by stringent requirements for compactness, dynamic response, safety compliance, and long-term reliability under frequent cycling—conducts an in-depth analysis of MOSFET selection considerations for key power nodes, providing a complete and optimized device recommendation scheme.
Detailed MOSFET Selection Analysis
1. VBGQA1103 (Single-N, 100V, 135A, DFN8(5X6))
Role: Main power distribution switch or high-current bridge leg in compact servo drives.
Technical Deep Dive:
Ultimate Power Density & Efficiency Core: Modern cobots operate on low-voltage DC buses (typically 48V or lower). The 100V rating of the VBGQA1103 provides ample safety margin. Utilizing advanced SGT technology, its Rds(on) is exceptionally low at 3.45mΩ (max) at 10V Vgs. Combined with a high continuous current rating of 135A, it minimizes conduction losses in the primary power path, directly extending battery life or reducing thermal load.
Space-Constrained Integration: The compact DFN8(5X6) package offers an outstanding power-to-size ratio, enabling high-density placement on tightly packed controller PCBs. This is critical for achieving the sleek and integrated joint designs essential in cobots. Its low gate charge facilitates high-frequency PWM operation, allowing for smaller output filter components and contributing to overall system miniaturization.
Dynamic Performance for Precision Control: The low on-resistance and package inductance ensure clean and fast current switching, which is fundamental for achieving high bandwidth in current control loops, resulting in smoother motion and higher positional accuracy.
2. VBED1303 (Single-N, 30V, 90A, LFPAK56)
Role: Primary switch for joint motor drive phases (Low-side in half-bridges) or compact DC-DC conversion within joints.
Extended Application Analysis:
Optimized for Low-Voltage High-Current Drive: Cobot joint motors often require very high peak currents for instant torque. The VBED1303, with its 30V rating, is perfectly suited for 24V or lower motor drives. Its trench technology yields an ultra-low Rds(on) of 2.8mΩ (typ) at 10V Vgs, making it one of the most efficient choices for minimizing losses in the final power stage.
Thermal Performance in Confined Spaces: The LFPAK56 package provides superior thermal resistance to the PCB, allowing effective heat dissipation through the board copper in space-constrained joint modules without bulky heatsinks. This directly supports high continuous torque output and reliability.
Enhanced Safety & Ruggedness: The low voltage rating and robust construction are ideal for Safe Torque Off (STO) compliant circuits. Its characteristics support fast demagnetization of motor phases when disabled, a key safety feature. The package is also highly resistant to mechanical vibration and thermal cycling, which is crucial for the dynamic and repetitive movements of a leased cobot.
3. VBQA2157N (Single-P, -150V, -22A, DFN8(5X6))
Role: Safety isolation control, high-side switching for auxiliary circuits (e.g., brake release, tool power).
Precision Power & Safety Management:
High-Voltage Side Control for Safety Functions: Cobots often integrate 24V or 48V safety circuits and may interface with higher voltage tooling. The -150V rating of this P-MOS provides robust isolation capability. It can be used as a reliable high-side switch to control critical safety loads like electromagnetic brakes or to isolate peripheral equipment power, ensuring failsafe operation.
Compact and Intelligent Integration: The DFN8 package allows this high-voltage switch to occupy minimal board space. Its logic-level compatible gate (Vth = -2V) allows direct control from safety MCUs or logic outputs, simplifying the control path and enhancing reliability. The low on-resistance (65mΩ @10V) ensures minimal voltage drop in critical safety paths.
Leasing Service Suitability: The independent control enabled by such a device allows for modular safety design and easier fault diagnostics. In a leasing context, where quick maintenance and verification of safety functions are paramount, this contributes to higher equipment availability and serviceability.
System-Level Design and Application Recommendations
Drive Circuit Design Key Points:
High-Current Motor Drive (VBGQA1103 / VBED1303): Require gate drivers with sufficient current capability and short propagation delays to minimize switching losses and ensure precise timing. Careful PCB layout to minimize power loop inductance is critical to prevent voltage spikes and ensure stable operation.
Safety & Auxiliary Switch (VBQA2157N): Can be driven directly by an MCU with a simple P-channel high-side driver circuit. Incorporating gate resistors and TVS protection is recommended to enhance noise immunity in the electrically noisy environment of a motor drive system.
Thermal Management and EMC Design:
Tiered Thermal Design: The VBGQA1103 and VBED1303 rely on efficient thermal connection to the PCB ground plane. For high-duty-cycle joints, consider thermal vias to inner layers or a metal core PCB. The VBQA2157N typically dissipates less heat but should still have adequate copper relief.
EMI Suppression: Employ gate resistors to control switching slew rates. Use high-frequency decoupling capacitors placed very close to the drain-source terminals of the motor drive MOSFETs. Proper shielding and filtering on all I/O lines are essential for cobots to meet strict EMC standards in diverse customer environments.
Reliability Enhancement Measures for Leasing:
Adequate Derating: Operate MOSFETs at no more than 60-70% of their rated current in continuous operation to account for shared thermal environments inside joints. Junction temperature monitoring via on-board sensors is highly recommended.
Multiple Protections: Implement independent current sensing and hardware overcurrent protection on each motor phase using the low Rds(on) of VBED1303 for accurate sensing. The VBQA2157N control loops should include diagnostic feedback to the safety controller.
Enhanced Robustness: Apply conformal coating to protect PCBs from dust and humidity, a common requirement in leased equipment moving between facilities. Ensure all connectors and MOSFET terminations are rated for high-cycle endurance.
Conclusion
In the design of high-performance, safe, and reliable power systems for collaborative robots destined for leasing services, power MOSFET selection is key to achieving high torque density, intrinsic safety, and maintenance-free operation over the lease term. The three-tier MOSFET scheme recommended in this article embodies the design philosophy of compactness, efficiency, and enhanced safety.
Core value is reflected in:
Maximized Performance in Minimal Space: The VBGQA1103 and VBED1303 deliver benchmark efficiency in ultra-compact packages, enabling powerful yet sleek cobot joints, a critical selling point.
Built-In Safety & Serviceability: The VBQA2157N provides a robust, integrable building block for safety-critical functions, facilitating compliance with safety standards and simplifying field diagnostics—a major advantage for leasing operators.
Lease-Life Reliability: The combination of low losses, robust packages, and appropriate derating ensures consistent performance and minimizes thermal stress over thousands of operating hours, reducing downtime and total cost of ownership for the lessee.
Future Trends:
As cobots evolve towards higher power, integrated force sensing, and mobile operation, power device selection will trend towards:
Increased adoption of integrated motor driver ICs for very small cobots, but discrete solutions like those recommended will remain dominant for higher-power axes.
Use of devices with even lower Rds(on) in advanced packages (e.g., dual-cooling) to push torque density limits.
Greater integration of diagnostic features (temperature, current) within the power switch package for predictive maintenance analytics, a key value-add for leasing services.
This recommended scheme provides a complete power device solution for collaborative robots, spanning from main power distribution and high-efficiency motor drive to safety isolation. Engineers can refine and adjust it based on specific cobot payload, number of axes, and safety integrity level (SIL/PL) requirements to build robust, high-performance, and service-friendly automation assets that form the backbone of modern flexible manufacturing and logistics enabled by robot leasing.

Detailed MOSFET Application Topology Diagrams