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CMCPCI102B
Application Information
Board Layout Recommendations
The CMCPCI102BT/BR devices should be located on
the board as close as possible to the CompactPCI con-
nector. Whether a signal is terminated or not depends
upon application, as shown in the following table:
Figure 7 shows a 64-bit system board connection
between the CMCPCI102BT/BR termination and the
CompactPCI 5-row connector (2 mm pitch) labeled A
to E (row F is Ground). The System slot should have
signal lengths not exceeding 63.5 mm (2.5 inches). To
minimize trace length, it is recommended that the
CMCPCI102BT/BRs be placed on alternate sides of
the PC board. The configuration shown illustrates a
fully-terminated 64-bit board utilizing 10
CMCPCI102BT/BR devices. Some applications (e.g.
32-bit boards) do not require all lines to be terminated,
per the above table.
The CMCPCI102BT/BR resistors have a very low TCR
(typically -100ppm/°C) so that resistance will not fluctu-
ate over temperature. Buffers are implemented on
P_EN, 5_EN and 3_EN inputs to ensure that switches
turn on and off completely.
A typical system slot card may use 10 CMCPCI102BT/
BR devices to replace 10 10-bit FET bus switches and
76 4-resistor packs (0805 form factor), thus providing
significant reduction in both component count and
assembly costs. At the same time this highly integrated
solution improves reliability and manufacturing effi-
ciency, saves board area for space-critical designs,
and satisfies CompactPCI height requirements. Figure 7. Schematic for 64-bit System Board
SIGNAL(S) SYSTEM SLOT
BOARDS
32-Bit 64-Bit
AD0-AD31 terminate terminate
C/BE0#-C/BE3# terminate terminate
PAR terminate terminate
FRAME# terminate terminate
IRDY# terminate terminate
TRDY# terminate terminate
STOP# terminate terminate
LOCK# terminate terminate
DEVSEL# terminate terminate
PERR# terminate terminate
SERR# terminate terminate
RST# terminate terminate
REQ64# terminate terminate
ACK64# terminate terminate
INTA#, INTB#, INTC#, INTD# (if
used)
terminate terminate
AD32-AD63 N/A terminate
C/BE4#-C/BE7 N/A terminate
PAR64 N/A terminate
*
*
*
*
*
*
Placed on
bottom side
of PC board