XRT73LC00A_08 Datasheet, PDF (53/63 Pages) Exar Corporation – E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73LC00A
E3/DS3/STS-1 LINE INTERFACE UNIT
REV. 1.0.1
FIGURE 31. TWO LIU’S, EACH MONITORING THE TRANSMIT OUTPUT SIGNAL OF THE OTHER LIU IC
DMO_Channel_2
U1
DMO
TXOFF
U2
DMO_Channel_1
TXOFF
DMO
TTIP
TRING
MTIP
MRING
R3
270 Ω
R4
270 Ω
MRING
MTIP
TRING
R5
270 Ω
R6
270 Ω
TTIP
R1
31.6Ω
R2
31.6Ω
T1
BNC
PE-68629
R7
31.6Ω
R8
31.6Ω
T2
BNC
PE-68629
Presented in Figure 31, if LIU # 1 (U1) fails, then LIU # 2 (U2) drives its DMO output pin “High”. Likewise, if LIU
# 2 (U2) fails, then LIU # 1 (U1) drives its DMO output pin “High”.
The scheme presented in Figure 31 is a better design approach. It overcomes situations in which a LIU
monitoring its own signal (Figure 30) may experience a failure mode such that it cannot drive a bipolar signal
onto the line. That same failure mode may prevent the LIU from driving the DMO output pin “High”.
4.6 The TAOS (Transmit All OneS) Feature
The XRT73LC00A can transmit an all “1’s” pattern onto the line by toggling a single input pin or by setting a
single bit-field in one of the Command Registers to “1”.
NOTE: When this feature is activated, the Transmit Section of the XRT73LC00A overwrites the Terminal Equipment data
with this all “1’s” pattern.
This feature can be activated by either of the following methods.
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