XRT73LC04A_08 Datasheet, PDF (47/64 Pages) Exar Corporation – 4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73LC04A
REV. 1.0.2
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
In some applications it is not desirable for a channel
within the E3/DS3/STS-1 LIU to recover data and
route it to the Receiving Terminal while the channel is
declaring an LOS condition. Consequently, the
XRT73LC04A includes an LOS Muting feature. This
feature, if enabled, causes a given channel to halt
transmission of the recovered data to the Receiving
Terminal while the LOS condition is "true". In this
case, the RPOS_(n) and RNEG_(n) output pins are
forced to "0". Once the LOS condition has been
cleared, then the channel(n) resumes normal trans-
mission of the recovered data to the Receiving Termi-
nal.
This feature is available whenever XRT73LC04A is
operating in the HOST Mode or Hardware Mode.
a. Operating in the Hardware Mode.
The Muting upon LOS feature is enabled by pulling
the LOSMUTEN output pin “High". This enables the
Muting upon LOS feature globally for all channels.
b. Operating in the HOST Mode.
The Muting upon LOS feature for each Channel can
be enabled by writing a "1" into the LOSMUT_(n) bit-
field within Command Register 3.
COMMAND REGISTER CR3-(n)
D4
D3
D2
D1
D0
(SR/DR)_(n)
LOSMUT_(n)
RxOFF
RxClk_(n)INV
Reserved
X
1x
x
x
x
NOTE: This step only enables the Muting upon LOS feature
within Channel(n).
3.6 ROUTING THE RECOVERED TIMING AND DATA
INFORMATION TO THE RECEIVING TERMINAL
EQUIPMENT
Each channel ultimately takes the Recovered Timing
and Data information, converts it into CMOS levels
and routes it to the Receiving Terminal Equipment via
the RPOS_(n), RNEG_(n) and RxClk_(n) output pins.
Each channel can deliver the recovered data and
clock information to the Receiving Terminal in either a
Single-Rail or Dual-Rail format.
3.6.1 Routing Dual-Rail Format Data to the
Receiving Terminal Equipment
Whenever a channel delivers Dual-Rail format to the
Terminal Equipment, it does so via the following sig-
nals.
• RPOS_(n)
• RNEG_(n)
• RxClk_(n)
Figure 28 illustrates the typical interface for the trans-
mission of data in a Dual-Rail Format from the Re-
ceive Section of a channel to the Receiving Terminal
Equipment.
.
FIGURE 28. THE TYPICAL INTERFACE FOR THE TRANSMISSION OF DATA IN A DUAL-RAIL FORMAT,
FROM THE RECEIVE SECTION OF THE XRT73LC04A TO THE RECEIVING TERMINAL EQUIPMENT
RxPOS RPOS
Terminal
Equipment
(E3/DS3 or STS-1
Framer)
RxNEG RNEG
RxClk RxClk
Receive
Logic
Block
Exar E3/DS3/STS-1 LIU
The manner that a given channel transmits Dual-Rail scribed below and illustrated in Figure 29. Each
data to the Receiving Terminal Equipment is de-
channel(n) typically updates the data on the
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