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ESP32 External RTC crystal Component Selection

Posted: Thu Dec 01, 2022 8:26 am
by dovov97815
Hello,
I am working on the Project in which I am using ESP32 WROOM 32E and this Project will be Battery Operated.

So my question is regarding using of External Crystal (RTC) and for that as per the Datasheet i have made connections of Crystal Oscillator and its Components.

As you can see in attached image;
1) You have given the Resistor value in the Range of 5M ohm to 10M ohm. So If I get 5M ohm then what will be the Impact on performance of Crystal and same question for 10M ohm Value.
2) Can you suggest us the Crystals and its Capacitor values?
3) Suggest the Value of R3 and R5 Resistors.
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Re: ESP32 External RTC crystal Component Selection

Posted: Fri Dec 02, 2022 6:18 am
by ESP_LJH
Basically, we tested that using impedance values among 5M and 10M will be helpful to activate crystal, but it is not easy to say impact difference between those values.
We commonly use SF32K32768D31T-12.5 and 12 pF as matching caps, you could consider those values as reference.
R3 and R5 could be 0.

Re: ESP32 External RTC crystal Component Selection

Posted: Mon Dec 05, 2022 6:22 am
by dovov97815
Can we use ABS25-32.768KHZ-T ?
Which value for R4 is recommended? 5M or 10M?