EELXT905PC.C2 View Datasheet(PDF) - Intel
Part Name
Description
MFG CO.
'EELXT905PC.C2' PDF : 38 Pages View PDF
LXT905 — Universal 10BASE-T Transceiver with 3.3V Support
2.7
Polarity Reverse Function
The LXT905 polarity reverse function uses both link pulses and end-of-frame data to determine
polarity of the received signal. If Link Integrity testing is disabled, polarity detection is based only
on received data. A reversed polarity condition is detected when eight consecutive opposite receive
link pulses are detected without receipt of a link pulse of the expected polarity. Reversed polarity is
also detected if four consecutive frames are received with a reversed start-of-idle. Whenever a
correct polarity frame or a correct link pulse is received, these two counters are reset to zero. If the
LXT905 enters the link fail state and no valid data or link pulses are received within 96 to 128 ms,
the polarity is reset to the default non-flipped condition. Polarity correction is always enabled.
2.8
Collision Detection Function
A collision is defined as the simultaneous presence of valid signals on both the TPI circuit and the
TPO circuit. The LXT905 reports collisions to the back-end via the COL pin. If the TPI circuit
becomes active while there is activity on the TPO circuit, the TPI data is passed to the back-end
over the RXD circuit, disabling normal loopback. Figure 6 is a state diagram of the LXT905
collision detection function.
Figure 6. Collision Detection Function
A Power On
TEN=Active ∗
TPI=Idle ∗
XMIT=Enable
Idle
TPI=Active
Output
TPO=TXD
RXD=TXD
Input
RXD=TPI
TEN=Active ∗
TPI=Active ∗
XMIT=Enable
TEN=Active ∗
TPI=Active ∗
XMIT=Enable
A
TEN=Idle +
XMIT=Disable
Collision
TPO=TXD
RXD=TPI
COL=ACTIVE
A
TPI=Idle
TEN=Active ∗
TPI=Idle
TEN=Idle
14
Datasheet
Document #: 249271
Revision #: 002
Rev. Date: June 19, 2001
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