[SI-LIST] Re: help: the ground under transformer and common mode choke
- From: "Zhang, Qing Nan (Qing Nan)" <zhangq@xxxxxxxxxx>
- To: weirsp@xxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Fri, 21 May 2004 15:33:45 +0800
Steve,
Thanks.
I don't understand your second part. Do you mean the noise is come from line
side ?
I draw a picture to indicate what I want to do to avoid unwanted noise
coupling to the signal lines.
Does this do help ?
Does this implemented yours' "Voiding logic ground in the vicinity of
magnetics "?
Best Regards,
Qingnan
<<hole in ground.doc>>
-----Original Message-----
From: steve weir [mailto:weirsp@xxxxxxxxxx]
Sent: 2004?5?20? 17:24
To: zhangq@xxxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: help: the ground under transformer and common mode
choke
The goal is to avoid unbalanced coupling of CM noise from logic ground into
the line side of the magnetics, not to attempt to isolate logic ground from
chassis. The latter will create even more noise that you will need to
isolate from the line side of the magnetics. Voiding logic ground in the
vicinity of magnetics is one way to reduce the possibility of unequal
coupling. You should place your magnetics and set your clearances
accordingly.
Regards,
Steve.
At 03:58 PM 5/20/2004 +0800, Zhang, Qing Nan (Qing Nan) wrote:
>Dear All,
>We know that the circuit ground and power plane is noisy. Thus we avoid to
>extend the circuit ground and power plane under the transformer and common
>mode choke to avoid RF emission.
>Does it do hlep when we make some holes in the ground plane under the
>transformers and chokes ?
>
>Thanks,
>Qingnan
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