From: Chris Cheng ([email protected])
Date: Fri Nov 05 1999 - 10:35:54 PST
have u look into using spread spectrum clock source instead of crystals ?
chris
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of [email protected]
> Sent: Wednesday, November 03, 1999 7:31 AM
> To: [email protected]
> Subject: [SI-LIST] : Micro Noise
>
>
> Hi all,
>
> I have a problem with a microprocessor which appears to be radiating very
> strongly from the package. I've deactivated all other circuits ( pulled
> crystals, pins etc ) on the board. Additionally, the micro is
> held in reset,
> PROM's are pulled, but it's a noisy as heck. Close field probes
> both E and
> H field ) show the package to be the dominent source of radiation.
>
> The device has a maximum clock rate of 50 MHz, this is where
> we're using it.
> Clock it at 32 MHz and the emissions fall about 10 dB up to about
> 300 MHz,
> more above 300 MHz. Yes it's a CMOS device.......
>
> Am I stuck with putting a can over the chip? The product has a plastic
> package, so there is no shielding available at all.....
>
> Thanks,
>
> Derek
>
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