T27.5 - Improving Dynamic Current Sharing Between Parallel MOSFETs by Optimizing Device Parameters

In today's applications, there is a persistent demand for higher power capabilities, where a single MOSFET is insufficient to meet the required power needs. To address this, designers often employ multiple MOSFETs in parallel to share the currents. However, paralleling leads to dynamic and steady state current imbalance issues, primarily caused by two factors: layout asymmetries and unmatched MOSFET parameters. These imbalances result in uneven power dissipation among the paralleled MOSFETs, which can compromise the overall system's performance and reliability. This paper showcases how latest 135 V and 150 V MOSFET technologies address the challenges associated with paralleling MOSFETs in high-power motor-drive applications such as Light Electric Vehicles (LEVs), e-scooters, e-forklifts etc. In this paper, a comprehensive comparison of dynamic current sharing between four parallel MOSFETs during hard turn-on and hard turn-off conditions will be demonstrated. Moreover, improvements in relevant device parameters, such as gate−source threshold voltage spread, showcase how the latest 135 V and 150 V MOSFETs can help minimize current imbalance, and enhance system reliability.