STM32U5 Max LSE bypass frequency documentation error

[Terry Greeniaus]

In STM32U575/585 RM0456 Rev 2 from September 2021, I see the following:

"11.4.7 LSE clock

...

External source (LSE bypass)

In this mode, an external clock source must be provided. It can have a frequency of up to 1 MHz."

However, in STM32U585xx DS13086 Rev 4 from December 2021, I see the following:

"5.3.7 External clock timing characteristics

...

Table 78. Low-speed external user clock characteristics

f_LSE_ext - User external clock source frequency

Min: 5 kHz

Typ: 32.768 kHz

Max: 40 kHz"

So, is the max LSE frequency in bypass mode 1 MHz or is it 40 kHz? On previous MCU families such as the STM32G4 an LSE frequency up to 1 MHz in bypass mode was supported.

Thanks!

[Bruno_ST · Accepted solution]

Hello @Terry Greeniaus​ 

Thanks for reporting, it will fixed in next release of the RM (no more max LSE freq in it).

The reference is the current datasheet, so max freq 40kHz (even if it is was more in other MCU families)

BR,

Bruno

[Terry Greeniaus]

Thanks for your reply!