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Graduate
February 3, 2024
Question

How supply STM32F446RET6

  • February 3, 2024
  • 5 replies
  • 2544 views

Hi, I want to design a board using STM32F446RET6 MCU. But I have a question about how to properly power the ADC system, and what the VCap_1 pin is. I read that I need to put a 4.7 uF ceramic capacitor with low ESR there. Below is an introductory graphic with a diagram. I added 100nF capacitors based on my previous projects using the STM32F103 series. But this time I will have to perform quite precise ADC measurements and work with the DAC.

I was thinking about using tantalum capacitors, but does it make sense?

 

f446_power.png

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    5 replies

    Super User
    February 3, 2024

    Here is the STM32F4 hardware design guide:

    http://nic.vajn.icu/PDF/STMicro/ARM/STM32F4/STM32F4xx_Hardware_Dev.pdf

    The bulk capacitor on VDD can be tantalum or ceramic. The VCAP cap should be ceramic. Why do you want to use a tantalum? BOOT0 need tied or pulled to ground. NRST should have a 0.1 uF cap. It's recommended to tie VBAT to VDD if you're not using it.

    Super User
    February 4, 2024

    > Here is the STM32F4 hardware design guide:

    It is maybe better to link ST's ANs from official ST site.

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

    JW

    MSzła.1Author
    Graduate
    February 3, 2024

    Thanks for the answer, regarding tantalum capacitors I have heard about their advantages, but the documentation shows that ceramic capacitors can also be used. Below is the corrected diagram where I added a 4.7 uF capacitor for the VCAP1 pin and an additional 1uF ceramic capacitor for the ADC system. I know about the BOOT1 pin, grounded to GND with 10k resistor :beaming_face_with_smiling_eyes:

    Capacitors:

    CL10A475KO8NNNC - for VCAP pin

    CL05A105KP5NNNC - for ACD supply

    rest of 100nF capacitors are GRM155R71H104KE14D

    Do you think everything will be fine now?

     

    ver2_f446.png

     

    Super User
    February 3, 2024

    It'll probably boot, but you're still missing some recommended things:

    TDK_0-1706991358907.png

     

    Also missing the recommended 0.1 uF on NRST.

    Also note you need a way to program it. I would recommend using SWD on a 14-pin header to a STLINKV3-MINIE p.

    Super User
    February 3, 2024

    >I was thinking about using tantalum capacitors, but does it make sense?

    NO.

    These are (for me) a "no go" . Ever seen a burning tantalum cap ?

    If you can avoid them - do it. Today cer caps are better - and dont burn a hole in the board. :)

    MSzła.1Author
    Graduate
    February 3, 2024

    I haven't seen it, so I won't use it :)

    MSzła.1Author
    Graduate
    February 3, 2024

    So, I copied a few things from the default project. I added a ferrite bead and a few other things, e.g. a programming socket,reset button or RTC baterry case.

     

    ver3_f446.png