STM32F401 PCB Design For Low Power Project

[ButterScotchCookie]

Hi, I'm doing a low-power project using the STMF401CCUx MCU. 

I require only 1 I2C, 1 SPI, 1 GPIO Interrupt, and 2 GPIO input pins. 

I won't be using any ADC or DAC parts, so is it fine to leave the VREF+ pin unconnected? 

Does it source any current? 

Any other recommendations on the PCB design is also appreciated. Thanks!

[TDK · Accepted solution]

> I won't be using any ADC or DAC parts, so is it fine to leave the VREF+ pin unconnected? 

No, it must be connected to a voltage per the datasheet. Just connect it to VDDA in the event you want to use ADC in the future. It does not pull significant current, certainly orders of magnitude less than other pins.

> Any other recommendations on the PCB design is also appreciated. Thanks!

Follow the hardware design guide and datasheet.

https://www.st.com/resource/en/application_note/an4488-getting-started-with-stm32f4xxxx-mcu-hardware-development-stmicroelectronics.pdf

https://www.st.com/resource/en/datasheet/stm32f401cb.pdf

There's probably better chips out there than the STM32F4 series for low-power if you have flexibility:

https://www.st.com/en/microcontrollers-microprocessors/stm32-ultra-low-power-mcus.html

[STOne-32]

 Dear @ButterScotchCookie ,

In our STM32F401CC power efficiency MCU having 48 Or CSP49 pins the VREF+ is bonded with VDDA pin which is mandatory to connect to VDD even ADC and DAC is not used as it power other Analog peripherals such as internal RC / HSI and PLLs . So Yes , please connect it to VDD . 

you can also refer to AN4488 here 

https://www.st.com/resource/en/application_note/an4488-getting-started-with-stm32f4xxxx-mcu-hardware-development-stmicroelectronics.pdf

Hole it helps you .

STOne-32

 

[Tesla DeLorean]

Aren't there L series chips which would be better suited for "Low Power", and not a decade old ?

You really need to put the horse in front of the cart here, and let primary goals drive choices rather than random convenience with the Black Pill or whatever.