FWLXT9784BE.A3 Cortina Systems Inc, FWLXT9784BE.A3 Datasheet - Page 39

• Manufacturer Part Number: FWLXT9784BE.A3
• Manufacturer: Cortina Systems Inc

Specifications of FWLXT9784BE.A3

• Lead Free Status / RoHS Status: Not Compliant

2.5.1
2.5.2
Datasheet
Table 14. Straight-through Pin Assignments
Table 15. Crossed-over Pin Assignments
cases that the cable type does not match the two ends MAUs configurations, replacement of the
cable is required. With the MDI/MDI-X feature enabled, switching is performed automatically by
the LXT9784, to adjust the MAU to the cable type.
This advanced feature enables auto-correction of a specific wiring problem of incorrect cabling
with respect to crossed-over versus straight-through cables. The LXT9784 PHY can identify the
cable connection type and adjust its MDI port to the cable by switching between the TPO and TPI
pairs. The auto switching is done prior to the auto-negotiation algorithm.
Table 14
on contacts 1 and 2, and the receive pair on contacts 3 and 6.
configuration of a crossed-over RJ-45 port.
MDI/MDI-X Auto Switching Activation
The external MDI-X input, sampled during reset, enables or disables auto-switching. When this
input is externally pulled up, or left unconnected, auto-switching is enabled. When MDI-X is
externally pulled down, auto switching is disabled. In the case that auto-switching was disabled
during reset, after reset the MDI-X pin is used to configure the connection type (straight-through or
crossed-over). A “1” forces a crossed-over connection, a “0” forces a straight-through connection.
MDI/MDI-X Algorithm
In the case that auto-switching was enabled during reset, the PHY attempts to detect link activity in
a given configuration (MDI or MDI-X) for a duration of 80 - 100 ms. If no link activity is detected
during this slot time, the PHY waits a random amount of time greater then 80 ms, and switches the
MDI pairs to the other configuration.
Contact
Contact
shows the standard DTE straight-through RJ-45 port configuration, with the transmit pair
1
2
3
4
1
2
3
4
5
6
7
8
RDP_n
RDN_n
TDP_n
Not used
TDP_n
TDN_n
RDP_n
Not used
Not used
RDN_n
Not used
Not used
MDI Signal
MDI Signal
Low-Power Octal PHY — LXT9784
Table 15
shows the MAU
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