2024-02-03 11:37 AM - edited 2024-02-03 11:40 AM
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?
2024-02-03 11:49 AM - edited 2024-02-03 11:50 AM
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.
2024-02-03 12:11 PM
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?
2024-02-03 12:18 PM - edited 2024-02-03 12:18 PM
It'll probably boot, but you're still missing some recommended things:
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.
2024-02-03 12:22 PM
>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. :)
2024-02-03 12:51 PM
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.
2024-02-03 01:00 PM
I haven't seen it, so I won't use it :)
2024-02-04 01:59 AM
> Here is the STM32F4 hardware design guide:
It is maybe better to link ST's ANs from official ST site.
JW