Question about the 32MhZ oscillator

RE: Question about the 32MhZ oscillator

JONATHAN LL — Fri, 12 Nov 2021 09:27:52 GMT

Hi,

You need to keep the two capacitors to load the crystal correctly.

CL * 2 - 4pF = C1 = C2

The 4pF is C_pcb + C_pin

Regards,
Jonathan

RE: Question about the 32MhZ oscillator

campestring — Tue, 18 Aug 2020 09:00:57 GMT

Hi, thank you for you reply !

for example if I choose this one : www.arrow.com/.../ecs-international

Should I remove the two capacitor in the schematic ? Or should I leave them ?

Thank you have a good day.

best regards,

Arnaud

RE: Question about the 32MhZ oscillator

JONATHAN LL — Thu, 13 Aug 2020 11:53:43 GMT

Hi Arnaud,

I would not recommend to use the crystal you linked as it is not according to the specifications and (HFXO specification).

The crystal oscillator is designed for use with an AT-cut quartz crystal in parallel resonant mode. To achieve correct oscillation frequency, the load capacitance must match the specification in the crystal data sheet.

Specs from BOM:
XTAL SMD 2016, 32 MHz, Cl=8 pF, Total Tol: ±40 ppm

This means it needs to be 8 pF and 60 Ohm and no more than ±40 ppm in total Tolerance.

Here are some example components that is within spec:
https://www.digikey.com/products/en/crystals-oscillators-resonators/crystals/171?k=&pkeyword=&sv=0&pv253=1398&pv253=1564&pv253=1940&pv253=2011&pv253=2439&sf=0&FV=-8%7C171%2C35%7C294760%2C46%7C8582%2Cmu60+Ohms%7C2082%2Cmu32MHz%7C2150&quantity=&ColumnSort=0&page=1&pageSize=25

I believe you can chose "cut tape" in digikey to by fewer components at the time.

Regards,
Jonathan