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CONCEPT IGBT drivers combine both digital and analog approaches. The highly integrated SCALE and SCALE-2 chipsets in every CONCEPT driver rely on a mixed-signal architecture. The individual strengths of digital building blocks and analog cells are strategically exploited to generate maximum performance.
As an example, digital startup control can be much more precise than its analog counterpart when all operating conditions, voltage variations and device aging are considered. Also, considerable chip area, and thus costs, can be saved by implementing digital filters and digital timing management.
The situation is very different if we look at IGBT short-circuit protection. Here, the inherent speed of analog signal processing is far superior to any affordable digital emulation where it would be necessary to wait for the next few clock cycles to accommodate the request.
Another example strongly in favor of analog circuitry is management of the IGBT’s switching characteristics by means of active clamping, di/dt control and dv/dt feedback. Digital programming of these features can naturally reduce the production costs for the driver. However, such a coarse “digital” adaption to an IGBT module is no match for the excessive fine-tuning needed to generate the optimum switching performance required of these costly power modules.
It is generally a question of how much performance compromise and digital overhead you are willing to spend for a fully digital IGBT driver – and if you are getting any benefit from doing so.
The IGBT or MOS power switch must always be considered as an analog device to make the most of its capabilities. The optimum driver will therefore be the actual interface between the digital domain and the analog “real world”.
We at CONCEPT believe that an integrated combination of analog and digital functionality exploits the best of both domains at an optimum cost/performance ratio.
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