I am designing a controller based on an ATMEGA328P-AU chip.

For the chip, I provided an external crystal oscillator at a frequency of 16MHz.

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As a resonator I use YSX321SL enter image description here

His description refers to load capacitors whose capacitance is equal to 12pF and ESR 60Ω (Max). I plan to use two load SMD capacitors with a capacity of 22pF each. The question is, did I choose the right capacity? Or is it worth reducing?

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    \$\begingroup\$ If the datasheet says you should use 12 pF capacitors, then the device might perform best with, well, 12 pF capacitance; is there any specific reason why you do not want to follow the specifications... \$\endgroup\$ – aschipfl Jun 12 at 9:25
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    \$\begingroup\$ The ESR value specified is that of the crystal itself and not the load capacitors. \$\endgroup\$ – Andy aka Jun 12 at 9:44
  • \$\begingroup\$ I have 22pF capacitors, I was thinking about using them. But now I will use 12pF capacitors to achieve reliable operation of the crystal. Thanks for the help! \$\endgroup\$ – Алекс Гарисон Jun 12 at 9:50

A 12 pF capacitor from each side of the crystal to ground will work just fine.

So like this:

enter image description here

C1 and C2 need to have a certain value (each capacitor being between 5 pF and 50 pF is normal) to make the oscillator work.

Use the wrong value capacitor and the oscillator circuit will not work reliably.

The only reason to change the values of the capacitors is if you need to make the oscillator work at a very precise frequency like 16.000000 MHz.

Then normally a trimmer 1 pf to 22 pF capacitor:

enter image description here

is used in parallel with the crystal.

But chances are that you don't need this.

The microcontroller doesn't care about the exact frequency of the crystal oscillator. The frequency you get when using 2 x 12 pF will be more than accurate enough for almost any purpose. Only if you're building a clock you might worry about this.

There is no need to use smaller capacitors, you will only increase the chance that the oscillator will stop working!

Also there is no need to worry about the ESR of the capacitors, any modern capacitor should just work.

So: just use two 12 pF capacitors connected like shown above, and stop worrying about this :-)

  • \$\begingroup\$ Ok, I will use two capacitors with a capacity of 12 pF each. Thanks for the help! \$\endgroup\$ – Алекс Гарисон Jun 12 at 9:48

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