[SI-LIST] Re: What will happen when short the SERDES IO to GND?

Richard:
 
   I'm instersted in "the hot plug protection rules". 
 
   For a CML type TX driver of a serial transceiver, what kind of circuit 
tricks shall we take to be compliant with hot plug rules?
   
Regards,
Neo
--- On Thu, 7/10/08, Ward, Richard <richard.ward@xxxxxx> wrote:

From: Ward, Richard <richard.ward@xxxxxx>
Subject: [SI-LIST] Re: What will happen when short the SERDES IO to GND?
To: "steve weir" <weirsi@xxxxxxxxxx>, "liuluping 41830" <liuluping@xxxxxxxxxx>
Cc: "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>, "wangyongjin@xxxxxxxxxx" 
<wangyongjin@xxxxxxxxxx>
Date: Thursday, July 10, 2008, 5:12 AM

As Steve says - it depends.

Many XAUI style output drivers use majority passive termination to positive 
supply. By connecting the output nods to gnd you'll be bypassing the
current control stage and starve it.

Most nodes should survive with the (usually) 50 Ohms between rails for short 
times. Most will meet the hot plug protection rules. Long times on smaller 
feature sizes could permanently damage the die due to the high 
electro-migration. Depends on the design/linewidths. ESD doesn't tend to catch 
these
events unless spikes at insertion/removal occur as well. But assumed you meant 
a DC short.

"short" or "terminate"? - big difference naturally.

Short will likely kill the signals, risks damage over time, terminate will 
likely give collapsed swing at best.

Regards,
Richard


      
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