LU5X34F Datasheet, PDF (4/26 Pages) Agere Systems – Quad Gigabit Ethernet Transceiver

LU5X34F
Quad Gigabit Ethernet Transceiver
Preliminary Data Sheet
July 2000
Functional Description (continued)
Parallel Output Port
Byte Alignment
When ENCDET = 1, the LU5X34F recognizes the
comma character and aligns this 10-bit character to the
word boundary, bits RX[0:9].
COMDET =1 when the parallel output word contains a
byte-aligned comma character. The COMDET flag will
continue to pulse a logic 1 whenever a byte-aligned
comma character is at the parallel output port, indepen-
dent of ENCDET. When ENCDET = 0, there are two
possible scenarios depending upon when the comma
character is received.
1. If byte alignment had been previously achieved when
ENCDET had been a logic 1, the COMDET flag will
continue to pulse a logic 1 whenever a byte-aligned
comma character is at the parallel output port. If a
comma character occurs that is not on the word
boundary, no attempt will be made to align this
comma character and the COMDET flag will remain
at a logic 0.
2. If byte alignment had not been previously achieved
when ENCDET had been a logic 1, then the first
(and only the first) comma character received will be
aligned to the word boundary. COMDET will pulse
when the comma character is aligned to the word
boundary.
Timing for the parallel output data and the 50 MHz to
62.5 MHz receive-byte clock is given in Table 14.
Two low data rate receive-byte clocks are available as
TTL compatible outputs during use of the parallel out-
put port in 10-bit mode. RXCLK1 is the receive byte
clock used by the protocol device to register bytes 0
and 2. RXCLK0 is the receive-byte clock used by the
protocol device to register bytes 1 and 3, and it is
180 degrees out of phase with RXCLK1. Both RXCLK1
and RXCLK0 can be stretched during byte alignment
but not truncated or slivered. The maximum allowable
frequency of these two clocks under all circumstances,
excluding start-up, will not exceed 80 MHz. The start-
up time is specified as 1 ms.
Loopback Mode Operation
A control signal input, EWRAP, selects between two
possible sets of inputs: normal data (HDINP, HDINN) or
internal loopback data. When EWRAP = 1, the serial
output ports, HDOUTP and HDOUTN, remain active.
The serial transmit data prior to the PECL output driver
is directed to the data recovery circuit, where clock is
recovered and data is resynchronized to the recovered
clock. Retimed data and clock then go to the serial-to-
parallel converter.
Table 2. Definition of Bit Transmission/Reception Order*
Serial Transmit/
Receive Rate
TXX[9:0]
1.0 Gbits/s to 1.25 Gbits/s TXX[0] bit serially transmitted first at
HDOUTXP, HDOUTXN
* Lower case X signifies channel A, B, C, or D.
RXX[9:0]
RXX[0] bit received first at serial inputs
HDINXP, HDINXN
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Lucent Technologies Inc.