I would like to know the specification for the XTAL use on the Apalis TK1 for the TK1 IC. Specifically, the Frequency stability and Frequency tolerance. I am guessing it’s the 12MHz XTAL on the back of the board is the main XTAL clocking the TK1.
There are actually four crystals on the module. The main crystal is a 12MHz for the TK1 SoC. This crystal has a frequency tolerance of 30ppm, a temperature range from -40 to 85°C and a temperature stability of 50ppm.
The next crystal is a 25MHz for the Ethernet controller. This one has 30ppm tolerance and temperature stability in a temperature range of -40 to 85°C
The third crystal is used for the K20 microcontroller. This one runs at 8MHz and has 50ppm for both, tolerance and temperature stability. The temperature range of this crystal is only -25 to 85°C
The last crystal is used for the RTC which runs at 32.768kHz. We are assembling a high quality device from Micro Crystal Switzerland with 20ppm frequency tolerance.