Power supply scheme on STM32L4 series

[jacinta sartor]

Posted on July 26, 2017 at 04:32

I'm doing the schematic design for a circuit board using the STM32L452CEU6.

I find the power supply scheme to be a little confusing. I've attached the supply scheme from the datasheet as well as my schematic.

Is what I've done so far correct?

Do I treat VDDUSB and VSS_3 as just another VDD/VSS pair with a 4.7uF cap and 0.1uF cap on?

#stm32l4 #power #supply #scheme

[Szymon PANECKI]

Posted on July 26, 2017 at 11:25

Hello,

Regarding VDDUSB pin and VSS_3 pin from your schematics: yes, please treat it as another pair of supply pins.

VDDUSB requires supply voltage in range of  3.0 to 3.6 V. I noticed, that you want to use 3.3V for VDD, so you can simply use the same voltage and apply it to VDDUSB as well. Based on MCU's datasheet and AN4555:

VSS_3 needs to be connected to GND.

Regarding decoupling of the VDDUSB, it is enought to use 1x100nF and 1x1uF. This example implementation you can find in AN4555 (see below), but your approach will be also fine.

During process of schematics design I strongly recommend you to follow rules and example reference design from

http://www.st.com/resource/en/application_note/dm00125306.pdf

. You will find there all needed information.

Good luck!

Regards

Szymon

[Vangelis Fortounas]

Posted on July 26, 2017 at 13:17

Hello!!

For VDDA and VSSA pins take in mind

https://my.st.com/content/ccc/resource/technical/document/application_note/group0/3f/4c/a4/82/bd/63/4e/92/CD00211314/files/CD00211314.pdf/jcr:content/translations/en.CD00211314.pdf

!

It will be very helpfull for your design!!