NRF52 Reference design component Unavailability

RE: NRF52 Reference design component Unavailability

Navdeep — Thu, 03 May 2018 20:45:53 GMT

Hi found the crystal on digikey with CL 8pf and frequency tolerance 30ppm.

www.digikey.ca/.../en

This would work fine?

RE: NRF52 Reference design component Unavailability

Øyvind Karlsen — Fri, 25 Sep 2015 14:17:38 GMT

ESR for this component is a little high for comfort.

RE: NRF52 Reference design component Unavailability

Øyvind Karlsen — Fri, 25 Sep 2015 14:17:05 GMT

Hi,

Please see the electrical specifications for the 32MHz crystal here. Look for a crystal within the following specifications:

Atleast 40ppm +/- for BLE usage
Max 12pF load capacitance
ESR lower than typically 80ohms(double check this in the electrical specification as it is dependent the shunt capacitance)

Also be aware that when you use a different load capacitance from the one used in the reference design you will need to change the capacitors C1 and C2.

C1 and C2 should be the same value and are calculated like this.

C1 = C_L * 2 - 4pF

That means that if you have a load capacitance C_L of 12pF you should use 20 pF for your C1 and C2 capacitors. If you end up with a capacitor off the E12 scale etc that you have available, switch to the one that is the closest approximation.

This means that either of the ones you have suggested will work.

Best regards,

Øyvind

RE: NRF52 Reference design component Unavailability

oliverhu — Fri, 25 Sep 2015 06:02:58 GMT

I found a similar crystal with same frequency, tolerance, frequency stability and load capacitance,but ESR is different. is it ok to replace the old one by this crystal.

new one : www.mouser.sg/.../