Hello @adc_6_6,
The PLL of RT595 provides an alternate high-frequency clock source for the Fusion DSP CPU if the required frequency is different from the main system clock.
You can see the clock distribution in the chapter 6 called "Clock Control" in the Reference manual. Additionally, config tools could be help you switch to these frequencies.
Also, if you experience any issue, do not hesitate to let me know.
BR
Habib.