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craig.sacco
craig.sacco
Associate
September 1, 2021
Solved

VCO frequency discrepancy in STM32H743 datasheet and reference manuals

There is a discrepancy between rev 8 of the datasheet and rev 7 of the reference manual regarding the PLL VCO output range parameter when the PLL is setup in wide VCO frequency mode.

In section 7.3.10 of the datasheet, the VCO output range is between 192 and 960 MHz.

In section 8.7.12 of the reference manual, the documentation regarding the VCC#VCOSEL bits in the RCC_PLLCFGR register specifies a VCO output range is between 192 and 836 MHz.

I am pretty sure that the datasheet description is correct as I haven't encountered any issues configuring the micro with a 960 MHz VCO output, but would like an ST representative to confirm that and an assurance that the reference manual will be amended in future revisions.

Cheers,

Craig

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Imen GH
Imen GHBest answer
ST Employee
September 2, 2021

Hello @craig.sacco​ ,

The datasheet is correct: the VCO output range is between 192 and 960 MHz.

On my side, I have raised the RM error to our team for correction.

Internal ticket number: 112725 (PS: This is an internal tracking number and is not accessible or usable by customers). 

Thanks for pointing out this typo.

Imen 

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3 replies

Imen GH
Imen GHBest answer
ST Employee
September 2, 2021

Hello @craig.sacco​ ,

The datasheet is correct: the VCO output range is between 192 and 960 MHz.

On my side, I have raised the RM error to our team for correction.

Internal ticket number: 112725 (PS: This is an internal tracking number and is not accessible or usable by customers). 

Thanks for pointing out this typo.

Imen 

Imen GH
Imen GH
ST Employee
September 2, 2021

When your question is answered, please close this topic by choosing Select as Best. 

Thanks :)

craig.sacco
craig.saccoAuthor
Associate
September 2, 2021

Thank you Imen :grinning_face:

Me thinks that the RM was not updated with new parameters when the Rev V silicon was introduced, and still reflected the limits of the Rev Y silicon.

May be a good idea to state those ranges in the RM depending on the silicon revision being used.

Cheers,

Craig

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