GOOD QUESTION

First I have two questions back
1) what is the fastest rise time we are dealing with here?
2) is there a driver at the edge of each card where the signal
   leaves the card? If not, how far does a driven signal travel
   before it leaves the card and goes onto the backplane?

Doug Brooks





At 01:07 PM 2/14/98 -0500, you wrote:
>We have a product that is a shelf with a backplane into
>which plugs 2 power supplies and 8 modules. The 8 modules
>are all in parallel to one another and are capable of
>talking to one another through the backplane.  A single
>module contains 2 boards that are each 50 ohm boards.
>These two board are also in parallel with each other.
>
>16 connectors in the backplane for 16 PCBs each
>50 ohms. For any type of configuration, a single
>50 ohm board is capable of talking to as many as
>2*N + 1  other 50 ohm boards where N = # modules in shelf
>and  1 = the other board in its own engine.
>
>In other words,
># modules in shelf      # of other 50 ohm boards one board
>                                  talks to through the backplane
>                          dependent upon configuration of
>                          shelf.
>
>1 module                         1 other 50 ohm board
>2 modules                        3 other 50 ohm boards
>3 modules                        5 other 50 ohm boards
>  ...                   ...
>8 modules                       15 other 50 ohm boards
>
>2 connectors of the same module are about 3/4 inch apart.
>2 connectors of different modules are about 5/8 inch apart.
>
>        Module #1          Module #2
>      |<-------->|<------>|<-------->|
>          3/4"      5/8"
>
>      0          0        0          0
>      0          0        0          0
>      0          0        0          0
>      0          0        0          0
>      ...        ...
>
>What should the impedance of the backplane be?
>50 ohms?  100 ohms?  800 ohms?
>
>
>Regards, Doug
>
>Private emails welcome
>
>mailto:[log in to unmask]
>
>################################################################
>DesignerCouncil E-Mail Forum provided as a free service by IPC using
LISTSERV 1.8c
>################################################################
>To subscribe/unsubscribe, send a message to [log in to unmask] with following
text in the body:
>To subscribe:   SUBSCRIBE DesignerCouncil <your full name>
>To unsubscribe:   SIGNOFF DesignerCouncil
>################################################################
>Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional
information.
>For the technical support contact Dmitriy Sklyar at [log in to unmask] or
847-509-9700 ext.311
>################################################################
>
>
>

################################################################
DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c
################################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body:
To subscribe:   SUBSCRIBE DesignerCouncil <your full name>
To unsubscribe:   SIGNOFF DesignerCouncil 
################################################################
Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information.
For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311
################################################################