ESP32 Forum

Hi all,

There's several crystal types with different ESR and Load Capacitance. What you've provided to us, inside datasheet, is a Frequency range between 2 and 40 Mhz and Frequency Stability of +/-10ppm.

I want to ask:
- There's also particular requirements about ESR and Load Capacitance?
- If I choose a crystal with a frequency that isn't a multiple of 40/20/10, can I get anyway 40/80Mhz on peripherals and 160Mhz as CPU clock?

Thank you!

I will need to check about the ESR, but for the second question, yes, you will be able to get 80/160/240 MHz CPU frequency and 80 MHz APB frequency. Crystal frequency determines CPU/APB frequency before the application startup, i.e. while first and second stage bootloaders are running. When application starts up, it enables PLL and switches the clock source to that.

Got reply from hardware guys:

Generally, once the crystal could start up to a certain amplitude, it would meet our requirements.
So don't worry about the ESR or load cap.

Current data sheet and hardware design guide for ESP32 only mentions the frequency of the main crystal. Are there stability and accuracy requirements? We currently use 10ppm, but 40-50ppm are cheaper. Are those an option?