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How supply STM32F446RET6

MSzła.1
Associate III

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

7 REPLIES 7
TDK
Guru

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.

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MSzła.1
Associate III

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 😁

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

 

TDK
Guru

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.

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AScha.3
Principal III

>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. 🙂

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MSzła.1
Associate III

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

I haven't seen it, so I won't use it 🙂

> 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