Datasheet

____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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Register Name :
LTISR
Register Description:
LIU Transmit Impedance Selection Register
Register Address:
base address + 0x04
Bit # 7 6 5 4 3 2 1 0
Name TXG703 TIMPOFF TIMPL1 TIMPL0 -- L2 L1 L0
Default 0 0 0 0 0 0 0 0
Bit 7: Transmit 2.048kHz G.703 Synchronous Mode (TXG703). Setting this bit to 1 configures the LIU to
transmit the 2048kHz synchronization signal described in G.703 section 13 on TTIP/TRING. When this bit
is set to
1, data from the transmit formatter is ignored.
Bit 6: Transmit Impedance Off (TIMPOFF). See section 10.13.2.4.
0 = Enable in
ternal impedance (termination) for the transmitter
1 = Disable internal impedance (termination) for the transmitter
Bits 5 to 4: Transmit Load Impedance (TIMPL[1:0]). These bits are used to select the transmit load impedance.
These bits must be set to match the cable impedance. Even if internal impedance is turned off (TIMPOFF=1), the
external cable impedance must be specified in this field for proper operation. For J1 applications, use 110
. See
section 10.13.2.4.
TIMPL1 TIMPL0
IMPEDANCE SELECTION
0 0
75

0 1
100

1 0
110

1 1
120

Bits 2 to 0: Line Build-Out Select (L[2:0])
. Used to select the transmit waveshape. The actual waveshape
depends on the values of this field and the T1J1E1S bit in the LTRCR regi
ster. See section 10.13.2.2.
E1 Mode
L2 L1 L0 IMPEDANCE NOMINAL VOLTAGE
0 0 0
75

2.37V
0 0 1
120

3.0V
T1/J1 Mode
L2 L1 L0 CABLE LENGTH
MAX
ALLOWED
CABLE LOSS
0 0 0
DSX-1, 0ft–133ft ABAM 100
 / 0dB CSU
0.6dB
0 0 1
DSX-1, 133ft–266ft ABAM 100

1.2dB
0 1 0
DSX-1, 266ft–399ft ABAM 100

1.8dB
0 1 1
DSX-1, 399ft–533ft ABAM 100

2.4dB
1 0 0
DSX-1, 533ft–655ft ABAM 100

3.0dB
1 0 1 -7.5dB CSU
1 1 0 -15dB CSU
1 1 1 -22.5dB CSU