In SX Microcontrollers, SX/B Compiler and SX-Key Tool, g_daubach wrote:

Thomas,

unfortunately, I don't have any information about transition timing either. I agree with you that sources for EMI problems can be the switching frequency and the transition time. In theory, an "ideal" transition, i.e. with no rise or fall time, is composed of an indefinite number of harmonics. As the SXes are designed to run at clock speeds of 50 MHz and even higher, I'm pretty sure that the transition times are shorter than 5 ns independently from the clock speed.

Therefore, good filtering of the supply voltage, and other methods for reducing EMI are always important, no matter which clock frequency and clock source you are using. During my experiments in the EMI lab, I found out that reducing the supply voltage helps a lot. So if you have the chance, you should consider running the SXes at 3.3V, for example.

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