[SI-LIST] : Micro Noise

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From: Lfresearch@aol.com
Date: Wed Nov 03 1999 - 07:31:26 PST


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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