DM9081F Ver la hoja de datos (PDF) - Unspecified
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DM9081F Datasheet PDF : 22 Pages
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DM9081
External Logic
A simple logic scheme is required when more than two
DM9081 chips are connected to increase the total number
of repeater ports. The external logic should have one input
(EXPOUT#) and one output (EXPIN#) for each DM9081
chip. This function is easily implemented in a PAL device,
using the following logical equations:
EXPIN1# =
EXPIN2# =
EXPIN3# =
.
.
.
EXPINn# =
EXPOUT2# &
EXPOUT1# &
EXPOUT1# &
.
.
.
EXPOUT1# &
EXPOUT3# &
EXPOUT3# &
EXPOUT2# &
.
.
.
EXPOUT2# &
….. EXPOUTn#
….. EXPOUTn#
….. EXPOUTn#
.
.
.
….. EXPOUTN-1#
The above equations are in positive logic, i.e., a variable is
true when asserted. An example of three banked DM9081
chips is shown in Figure 1. The cascade IC number
recommended: under 3 and inclusive.
Note that if the design includes only two DM9081 chips,
then EXPOUT1# is connected to EXPIN2#, EXPOUT2# is
connected to EXPIN1#, and no external logic is required.
A single PAL16L8 performs the arbitration function for a
repeater based on several DM9081 chips.
Figure 1. Multiple DM9081 Devices
8
Final
Version: DM9081-DS-F01
April 22, 1997
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