voltage and temperature in corner cases

     Hello,
     
     maybe someone already asked this question in the past, I don't know.
     
     I'm trying to figure out how to tweak all the parameters to exercise
     worst case simulations. Let's take the example of a strong and fast
     driver. The C_comp and parasitics will be the only parameters of the
     driver to be weak. All receiver parameters will be weak (parasitics
     and clamping diodes only). Let's say I tune the parameters of the PCB
     to be weak also. So far everything is logical.
     
     I've got a problem with the voltage and temperature parameters. Let's
     say I have ibis models for 5V cmos device, where min and max
     parameters were extracted in the following conditions :
     
     min = minimum voltage, max temp deg C
     max = maximum voltage, min temp deg C
     
     then, I would have to supply the driver with 5.5V and the receiver
     with 4.5V which is absolutely not realistic. This case never happens
     on a motherboard. Also what voltage should be used to connect the
     components tied to Vcc in between them ?
     
     Same thing for the temperature. There will never be let's say @ -50C
     on one side and +70C on the other side. Moreover, what temperature
     value shall I give to the simulation software for the components in
     between the driver and receiver ?...
     
     In summary : what are the Vcc and temp values I shall use for the
     corner case simulations ?
     
     thanks and best regards,
     
     Jean-Christophe PAUTRAT,
     R&D Engineer, Design Engineering
     Commercial Desktop Computer Division,
     H E W L E T T - P A C K A R D

 
Received on Wed Jul 16 08:16:55 1997