Re: questions (fwd)

[Ron McNabb <rmcnabb@uiuc.edu>]

Hi Fred,
I know that Volodya had  ECL inputs connected to our FIFO for testing 
and it still works. 
Ron

Frederick Gray wrote:

>On Fri, Mar 31, 2006 at 07:23:39PM +0200, Ron McNabb wrote:
>  
>
>> Hi Peter,
>>Yes, we have the the ECL/LVDS input FIFO. It will accept either one. The 
>>only other option is NIM inputs.
>>Ron
>>    
>>
>
>Dear Peter and Ron,
>
>I just removed one of the little input daughtercards.  It contains two
>National Semiconductor DS90C402 LVDS receivers and a little bypass capacitor. 
>The absolute maximum rating on this device allows input signals from 
>-0.3 V to Vcc+0.3 V.   Consequently, ECL levels of -1.75 V and -0.9 V are out 
>of range and may destroy the chip.  I suspect that there are ESD protection 
>diodes on the pins, and that a negative signal causes a current to flow
>through them.  The absolute maximum rating would be set by the power 
>dissipation limit in the diodes.  (The recommended operating range is 
>from 0 V to +2.4 V.)
>
>The reason for the question is that, well, I connected some ECL signals
>to this FIFO for a few minutes yesterday.  I do not know whether I
>actually caused any damage, but it certainly explains why there was no 
>data collected.
>
>(For Ron: The FIFOs used for the muCap ePC readout have an ECL receiver 
>instead -- ON Semiconductor MC10H125P.  For some mysterious reason, all of 
>these chips were destroyed during the interval between runs.)
>
>Thanks,
>
>-- Fred
>
>-- Fred Gray / Visiting Postdoctoral Researcher                 --
>-- Department of Physics / University of California, Berkeley   --
>-- fegray@berkeley.edu / phone 510-642-2438 / fax 510-642-9811  --
>  
>