[SI-LIST] : UART Configuration corrution

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From: yaserh (yaserh@accessme.com.eg)
Date: Fri Jan 19 2001 - 12:32:07 PST


Hi All
I have designed a Microprocessor based card (80C88-8 MHZ operation) which includes a stand alone UART and this card is connected with other 3 cards using a backplane and another switche mode power supply card (40kHz switching frequency) to generate the 5V supply to the cards and feeds the supply through the backplane.

The system works will and no problem in operation, the problem is when any load connected to the same AC plug switches on and off the serial communication with my system stops and the system other operations still working will and the microprocessor is working well and is not hunged.

I have made tracing to the problem, the conclusion i have reached that the configuration of the UART is corrupted and i must refresh it again when i make a regular refresh of the configuration the problem does not happen. When i mointor the supply using DSO during load switching i noticed that a spikes over and down the 5V by 2V appears. Taking into considration that i use a line filter and my power supply board has a ground layer and i have an LC filter on the power enterance to the microprossor card.

I need the help why the microprossor and the system RAM does not effected by this transients and the UART only effected and why this happans. How i can make this spikes on supply disappers.

Waiting your reply
With my best regards
Yasser

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