DJLXT908LC Просмотр технического описания (PDF) - Intel

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DJLXT908LC

Universal 3.3V 10BASE-T and AUI Transceiver

Intel 

LXT908 — Universal 3.3V 10BASE-T and AUI Transceiver

SQE must be disabled for normal operation in hub and switch applications. In twisted-pair

applications, the SQE function is disabled when DSQE is set High, and enabled when DSQE is

Low. When using the 10BASE-2 port of the LXT908, the SQE function is determined by the

external MAU attached.

Figure 5. SQE Function

Power On

Output Idle

DO=Active

Output Detected

DO=Idle

SQE Wait Test

Start_SQE_Test__Wait_Timer

XMIT=Disable

SQE_Test__Wait_Timer_Done ∗

XMIT=Enable

SQE Test

Start_SQE_Test_Timer

CI=SQE

2.1.6

2.1.7

SQE_Test_Timer_Done

Polarity Reverse Function

The LXT908 polarity reverse function uses both link pulses and end-of-frame data to determine

polarity of the received signal. A reversed polarity condition is detected when eight opposite

receive link pulses are detected without receipt of a link pulse of the expected polarity. Reversed

polarity is also detected if four 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

LXT908 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. If Link Integrity Testing is disabled,

polarity detection is based only on received data. Polarity correction is always enabled.

Loopback Function

The LXT908 provides the normal loopback function specified by the 10BASE-T standard for the

twisted-pair port. The loopback function operates in conjunction with the transmit function. Data

transmitted by the back-end is internally looped back within the LXT908 from the TXD pin

through the Manchester encoder/decoder to the RXD pin and returned to the back-end. This

“normal” loopback function is disabled when a data collision occurs, clearing the RXD circuit for

the TPI data. Normal loopback is also disabled during link fail and jabber states.

14

Datasheet

Document #: 249049

Revision #: 002

Rev. Date: June 19, 2001

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