Article View: sci.electronics
Article #3058Bus Termination
From: Chuck_SirVAX_Staatse
Date: Thu, 14 Sep 1989 13:24
Date: Thu, 14 Sep 1989 13:24
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1396 bytes
Has anyone used a backplane termination technique combining both
series and parallel termination? Supposedly it reduces the swing
between Vhigh and Vlow on the backplane which reduces noise. The
circuit in question would look like this:
+5V
|
_|_
|R1 |
| |
-|-
|
| --------
|----------| R4 |---C
-------- | --------
A---------| R2 |---B
-------- |
_|_
|R3 |
| |
-|-
|
GND
The idea is to make R2 and R4 about 1/5 the resistance of R1 or
R3. Point A and C are bi-directional drivers. If point A is driven
to 0 volts the voltage divider R1,R2 causes point B to sit at
about .8 volts ,conversly, if point A is driven to 5 volts
the voltage divider R2,R3 causes point B to sit at around 4.2
volts. If point C is CMOS with Vtp -1.2 and Vtn of 1.2 then
point C will switch properly.
Anyone used this? Had problems with it?
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arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!portal!cup.portal.com!Chuck_SirVAX_StaatseShow Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!portal!cup.portal.com!Chuck_SirVAX_Staatse From: Chuck_SirVAX_Staatse@cup.portal.com Newsgroups: sci.electronics Subject: Bus Termination Message-ID: <22144@cup.portal.com> Date: 14 Sep 89 13:24:55 GMT Organization: The Portal System (TM) Lines: 32