ML4642
FUNCTIONAL DESCRIPTION
a type 2 configuration offers three options. In option 1,
when tied to +5 volts through a resistor and an LED, an
internal or external MAU will be connected. For stand-
alone operation without an internal or external MAU a
loopback is required. Option 2 allows loopback with no
SQE test while option 3 provides loopback with an SQE
test.
SQE TEST WHEN CASCADING
As mentioned before, after each transmission during the
interpacket gap time the collision signal will be activated
on the CDOUT pair of the same port as the TXIN pair
which received the packet. When cascading ML4642s to
implement 4 or 8 port designs, the path is remembered
and followed to acheive this function. The paths that did
not carry the transmit data blocks CDOUT for 4-7 µsec
after transmission to guarantee that only the port that
transmitted will see SQE test.
An eight port design is accomplished in the same way as
shown in the block diagram in Figure 11. In an eight port
design Type 0 and Type 2 configuration remain the same
as in a four port design. Type 1 however only differs from
Type 2 by tying RXLED/LPBK/SQE through a resistor to +5
volts. Table 1 summerizes all of the different LED
configurations.
TABLE 1. LED Configurations for 2, 4, and 8 Port Designs
JAB1/JABD
LED
RXLED/LPBK/SQE
GND, 0.6V, LED
270ý to +5V
JAB2
LED
LED
NC
CDLED
LED
TXLED1
LED
TXLED2
LED
Two Port AUI Mux
Type 0
LED
WIRE’ORED
NC
LED
LED
Type 1
GND
270ý to +5V
NC
NC
Type 2
GND
GND, 0.6V, LED
NC
NC
NC
NC
TYPE 0
TYPE 1
TYPE 2
DTE PORT 1
ML4642
ML4642
ML4642
ML4642
DTE PORT 2
ML4642
DTE PORT 3
DTE PORT 4
ML4642
MAU PORT
DTE PORT 5
DTE PORT 6
ML4642
DTE PORT 7
DTE PORT 8
Figure 11. Eight Port AUI Multiplexer
13
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
