Grounding the crystal body

[Murugesh_89]

Hi,
I saw some circuits where the crystal oscillator's body is grounded.

What is the usefulness of doing this?

Also is there any disadvantages of doing this as i saw many circuits where body of crystal is not grounded?

Thanks,
Murugesh

 

[Vengateswaran]

I think there is no disadvantage in doing that... It is just done to prevent unwanted oscillations, if we using the crystal working at high frequency.

 

[betwixt]

It provides some degree of screening against capacitive coupling into the crystal and also in some cases is done for mechanical stability.

Brian.

 

[Murugesh_89]

If a current passing through the board is 20A and if we ground the crystal body then, will this high current passing through the crystal body heat it and there by will create any malfunction?

 

[betwixt]

If you pass 20A through a crystal can it will warm up and yes it will shift frequency. However, anyone who uses a crystal can to conduct ANY current has to be taken out and shot several times until they learn not to do it again. The can should be grounded at one point or at least to points of equal potential and ideally very close the the ground of the oscillator/filter it is connected to.

Please refer to guidlines for building crystal oscillators, they will explain proper board design, especially grounding around the oscillator components and how to avoid other currents flowing nearby.

Brian.