Minimum Frequency for Bypass mode

[Chubs]

Hello Community,

I am working on a use case where I have 4 remote MCUs that ideally should be synced with a host MCU. I however have no way to even install an external precision Clock source on these remote MCU's (due to various environmental & budget limitations), while I can accept a precision reference clock signal from any external device that is off-board ie of PCB via one available differential channel on my CAT6e cables. I wish to seek your insights to confirm my assumptions & clear my doubts if I can use this external Clock source to clock the HSE & replace the lower +-5% stability internal 16Mhz HSI on STM32G0B0 MCUs.

Point #1:

The Datasheet does NOT mention any minimum frequency for the external clock signal to HSE as input clock refernce, so in theory (for sake to my understanding) does this mean I can use a signal as low as 32Khz for driving the MCU? Or am I missing something obvious here?

The Datasheet mentions no minimu frequency limit for an external clock source

Then in theory, can I also use a stable 50/60Hz signal that is available to clock the MCU?

Point #2:

Further I am confused, as the Datsheet of the STM32G0B0RET6 mentions the HSI16 has +-5% stability on the first page, while the internal page on clock charectiristics mentions it has ~1.25% stability 

Clock characteristics mentioned inside the Datasheet

Clock stability mentioned on the front page of the same Datasheet!

I am confused, is this a major typo in the datasheet or am I missing something here?

Your insights shall be appreciated.

[TDK · Accepted solution]

1) No minimum, correct. But note that PLL has minimums which will give you a restriction if you use PLL for anything. Note that 50/60 Hz mains frequency is not particularly accurate either.

The reference manual will give you more information. The PLL restrictions are listed there.

2) Seems like a typo to me. The "features" section is less accurate in general in my experience.

[STTwo-32]

Hello @Chubs 

thank you for your request.  I will check this internally and come back to you as soon as possible.

Best Regards.

STTwo-32

[STTwo-32]

Hi again @Chubs 

Thank you for having reported this issue.

An internal ticket (number: 167147) is submitted to escalate this issue internally for check and analysis.
(PS: number 167147 is an internal tracking number and not available outside of ST).

Best Regards.

STTwo-32

[Tesla DeLorean]

CMOS, should clock to DC, wants 50/50 duty, VCO frequencies, dividers, and comparison frequency should limit viable rates for PLL

Most power distribution these days is monitored by GPS