EELXT905PC.C2 データシートの表示（PDF） - Intel

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EELXT905PC.C2

Universal 10BASE-T Transceiver with 3.3V Support

Intel 

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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