problem using PLL as SYSCLK over 200MHz on H5

[mete]

I am trying to increase FCLK, and I changed the voltage scaling to VOS0, and configured the PLL1 for 240 MHz (src=HSI (HSIDIV=2), M=2, N=30, P=2), but it did not boot (it freezes when a change the system clock mux to PLL1). I realized when I decrease it to 200MHz or so, it works. If I increase it, it does not. It is also same if I change M to 4 and N to 60. The PLL configuration looks valid on the configuration tool. What might I be missing ?

I also tried monitoring PLL1 and SYSCLK on MCO2 and both shows correct 240MHz with the above configuration even if the processor freezes.

(Note: I am not using HAL and the device is STM32H563ZI)

[liaifat85]

Double-check the power supply and stability of your voltage levels. Sometimes, pushing the clock too high can cause instability if the power supply isn't robust enough.

[mete]

I am using the NUCLEO H563ZI board and powering from USB. Not sure if it has a limit but you are probably right, I cant think of any other reason yet.

[SofLit · Accepted solution]

Hi @mete ,

Check also the flash memory wait states number (from RM0481 rev 1 / Table 37):

In your case it should be 5WS.

[mete]

Totally forgot about the wait states. Thanks for reminding. I changed it and it works fine.