STM32U585 VCAP capacitor voltage

[Rameshwin]

Hi,

 

I am using STM32U585 IC. I have a question on VCAP (L10) pin capacitor requirement. In recent datasheet it is mentioned rated voltage of the cap to use >10V. Why is it recommended to use10V rated cap for a maximum of 3V on pin. I have a concern on capacitor package. Can I use 6.3V capacitor part?

Also what is the minimum capacitance requirement? If I take DC bias and tolerance considerations of X7R capacitor, I might get around 3.0uF. Is this acceptable?

https://www.st.com/resource/en/datasheet/stm32u585ai.pdf

(refer p.no 150)

[TDK]

Please take a look at the hardware design guide for that chip.

https://www.st.com/resource/en/application_note/an5373-getting-started-with-stm32u5-mcu-hardware-development-stmicroelectronics.pdf

De-rating capacitors is standard industry practice (although not to the level that the datasheet recommends). Capacitors should be derated in general to (a) account for voltage spikes and (b) provide the capacitance they actually state. Look up capacitance vs voltage curves for capacitors and you may find it informative.

If the datasheet has a recommendation, it is recommended that you follow the recommendation.

All that said a 3.0 uF X7R will likely work fine, but it doesn't follow the recommendations. Up to you if you want to take the risk.