Post by thread:[EE] Ground return of the caps of a Xtal

Hi! Should I return the ground of the caps of a xtal to the nearest Vss pin of the MPU, or returning them to the opposite side, where I have a ground plane readily available, is exactly the same? I heard the first would be better.. but will it really make any difference? Cheers, Mario

My strong advice would be to return those caps by a dedicated, isolated track to the nearest uP ground pin to the crystal pins. On the other side of the PCB, connect the uP ground pin to the plane. This approach works well, both in keeping emi radiation down and keep other currents out of the crystal. Your cap values should be a few pf less than twice the load cap spec of the crystal. Electron <spam_OUTelectron2k4TakeThisOuTinfinito.it> wrote: {Quote hidden}> >Hi! >Should I return the ground of the caps of a xtal to the nearest Vss pin >of the MPU, or returning them to the opposite side, where I have a ground >plane readily available, is exactly the same? > >I heard the first would be better.. but will it really make any difference? > >Cheers, >Mario > >

> My strong advice would be to return those caps by a dedicated, > isolated track to the nearest uP ground pin to the crystal pins And ground the crystal case too. That's solved mysterious micro behaviour a couple of times for m

Agreed though I've all but given up arguing that one. IVP <.....joecolquittKILLspam@spam@clear.net.nz> wrote: >> My strong advice would be to return those caps by a dedicated, >> isolated track to the nearest uP ground pin to the crystal pins > >And ground the crystal case too. That's solved mysterious micro >behaviour a couple of times for me >

Thank You all for the insights, I will implement all the suggested modifications. Cheers, Mario At 05.09 2012.05.27, you wrote: >Agreed though I've all but given up arguing that one. > >IVP <joecolquittKILLspamclear.net.nz> wrote: > >>> My strong advice would be to return those caps by a dedicated, >>> isolated track to the nearest uP ground pin to the crystal pins >> >>And ground the crystal case too. That's solved mysterious micro >>behaviour a couple of times for me >>-