XRT73LC04A_08 Datasheet, PDF (35/64 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
a. Operating in the HOST Mode.
When the XRT73LC04A is operating in the HOST
Mode, then the HDB3/B3ZS Encoders within each
channel can be individually enabled or disabled. Dis-
able the HDB3/B3ZS Encoder block within Chan-
nel(n) by setting the (SR/DR)_(n) bit-field within Com-
mand Register (CR3-(n)) to "1" as illustrated below.
COMMAND REGISTER CR3-(n)
D4
D3
D2
D1
D0
(SR/DR)_(n)
LOSMUT_(n)
RxOFF
RxClk_(n)INV
Reserved
1
X
X
X
X
NOTE: This method can only be used if the XRT73LC04A is
operating in the HOST Mode.
If either of these methods are used to disable the
HDB3/B3ZS Encoder, then the LIU transmits the data
as received via the TPData_(n) and TNData_(n) input
pins.
2.4 THE TRANSMIT PULSE SHAPING CIRCUITRY
The Transmit Pulse Shaper Circuitry consists of a
Transmit Line Build-Out circuit which can be enabled
or disabled by setting the TxLEV_(n) input pin or
TxLEV_(n) bit-field to “High”or "Low". The purpose of
the Transmit Line Build-Out circuit is to permit config-
uration of each channel to transmit an output pulse
which is compliant to either of the following pulse
template requirements when measured at the Digital
Cross Connect System. Each of these Bellcore spec-
ifications state that the cable length between the
Transmit Output and the Digital Cross Connect sys-
tem can range anywhere from 0 to 450 feet.
The Isolated DSX-3 Pulse Template Requirement per
Bellcore GR-499-CORE is illustrated in Figure 19 and
the Isolated STSX-1 Pulse Template Requirement
per Bellcore GR-253-CORE is illustrated in Figure 20.
FIGURE 19. THE BELLCORE GR-499-CORE TRANSMIT OUTPUT PULSE TEMPLATE FOR DS3 APPLICATIONS
DS3 Pulse T em plate
1.2
1
0.8
0.6
Lower Curve
Upper Curve
0.4
0.2
0
-0.2
-1 _{-0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1}
0 _{0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9}
Time, in UI
1 _{1.1 1.2 1.3 1.4}
31