Power Semiconductor Device - Parameters of Power Semiconductor Devices

Parameters of Power Semiconductor Devices

1. Breakdown voltage: Often, there is a trade-off between breakdown voltage rating and on-resistance, because increasing the breakdown voltage by incorporating a thicker and lower doped drift region leads to a higher on-resistance.
2. On-resistance: A higher current rating lowers the on-resistance due to greater numbers of parallel cells. This increases overall capacitance and slows down the speed.
3. Rise and fall times: The amount of time it takes to switch between the on-state and the off-state.
4. Safe-operating area: This is a thermal dissipation and "latch-up" consideration.
5. Thermal resistance: This is an often ignored but extremely important parameter from the point of view of practical design; a semiconductor does not perform well at elevated temperature, and yet due to large current conduction, a power semiconductor device invariably heats up. Therefore such a devices needs to be cooled by removing that heat continuously; packaging and heatsink technology provide a means for removing heat from a semiconductor device by conducting it to the external environment. Generally, a large current device has a large die and packaging surface areas and lower thermal resistance.