Clarification on Crystal Oscillators in STM32L432KCU6

[Nikunj_17]

Hello,

I am working with the STM32L432KCU6 microcontroller and noticed that it includes a 32.768 kHz crystal. I would like to confirm whether there is a separate crystal for high-speed operation or if an external high-speed crystal needs to be added. Could someone clarify this for me? Any insights would be greatly appreciated.

Thank you!

Nikunj

[Tesla DeLorean]

LSI is not a crystal.

MCU will start off MSI or HSI. Check Datasheet and Reference Manual.

[mƎALLEm]

Hello,

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@Nikunj_17 wrote:

I am working with the STM32L432KCU6 microcontroller and noticed that it includes a 32.768 kHz crystal.

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There is no MCU in this world embedding a crystal. The crystal needs to be added externally.

May be you are talking about a board? if that case, which board? 

In case you need to add two crystals for LSE and HSE on your board.. yes they are separated.

PS: you said crystal oscillator but you need to know there are differences between Crystal (XTAL) and Crystal oscillator (XO). See this link.

[Nikunj_17]

Thanks for your answer!
Does this controller support an HSE crystal? Also, what is the actual function of PA0?

[mƎALLEm · Accepted solution]

Checking The datasheet of STM32L432KCU6. It's a UFQFPN32 package.

LSE is using PC14 and PC15

HSE is using only PA0 and that case you need to use a crystal oscillator (XO)

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@Nikunj_17 wrote:

Does this controller support an HSE crystal? Also, what is the actual function of PA0?

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No. Its doesn't support a Crystal for HSE but a Crystal oscillator (XO) as described in this link. XO has only one input that needs to be connected to PA0/CK_IN pin of the MCU.

Hope that helps.

[Tesla DeLorean]

>>Does this controller support an HSE crystal?

As I recollect there is an STM32G0 or C0 which shares this form-factor, but supports an HSE bonded to the PC14/PC15 pins

PA0 / CK can take a TCXO, or other CMOS clock from another device.

[Nikunj_17]

Hello,

Thank you so much for the confirmation.

Please recommend a suitable crystal oscillator (XO) to connect to the PA0/CK_IN pin and provide the recommended circuit.

[Andrew Neil]

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@Nikunj_17 wrote:

Please recommend a suitable crystal oscillator (XO) to connect to the PA0/CK_IN pin 

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In this role, it's just a straightforward digital input pin - like any other digital input pin - see the datasheet for the specifications.

[mƎALLEm]

Hello,

An exemple of a crystal oscillator with a power supply of 3.3V: https://www.farnell.com/datasheets/1998820.pdf

Please accept as solution the commment that answerd your original question.