crystal oscillator question

[ccesaretto]

Hello.
This question is very basic, sorry for that.

For a project I am considering this crystal oscillator:

http://uk.farnell.com/abracon/abm8g-12-000mhz-4y-t3/crystal-12mhz-10pf-3-2-x-2-5mm/dp/2467837

It's different from the oscillators I have previously used because it has four pads instead of just two.
Two of the pads are marked with GND in the datasheet so it looks like they have to be connected to ground.

or not?

Thank you for they help.

Cristiano

[dannyf]

You likely had a crystal: tough for an oscillator to have just two pads. A crystal needs a driver to output a clock.

A crystal oscillator is just a crystal plus it's driver.

[ccesaretto]

Thank you for the reply but now the confusion in my head is even bigger   

At the moment I am using this:

http://uk.farnell.com/multicomp/hc49sm-12-30-50-60-16-atf/crystal-hc-49-4hsmx-12-0mhz/dp/1667016

connected to the two OSC pins of a PIC microcontroller and to the load caps.

I was thinking of replacing it with this:

http://uk.farnell.com/abracon/abm8g-12-000mhz-4y-t3/crystal-12mhz-10pf-3-2-x-2-5mm/dp/2467837

just because it is smaller. but it has the two GND pins that the first one does not have.

[bobaruni]

Yes it is the same, just has extra pads for mounting onto PCB.
Also remember to change your capacitors to match the crystal, in this case 10pF.

[dannyf]

Both are crystals, not crystal oscillator.

[ccesaretto]

Both are crystals, not crystal oscillator.

Ok, thanks. Now it is clear