Datasheet

DS26514 4-Port T1/E1/J1 Transceiver
19-5856; Rev 4; 5/11 238 of 305
Register Name:
LTIPSR
Register Description:
LIU Transmit Impedance and Pulse Shape Selection Register
Register Address:
1001h + (20h x (n - 1)) : where n = 1 to 4
Bit #
7
6
5
4
3
2
1
0
Name
TG703
TIMPTON
TIMPL1
TIMPL0
—
L2
L1
L0
Default
0
0
0
0
0
0
0
0
Bit 7: Transmit G.703 Synchronization Clock (TG703)
0 = Normal transmitter mode.
1 = G.703 2.048MHz clock transmitted on TTIPn and TRINGn.
Bit 6: Transmit Impedance On (TIMPTON)
0 = Disable transmit terminating impedance.
1 = Enable transmit terminating impedance.
Bits 5 and 4: Transmit Load Impedance 1 and 0 (TIMPL[1:0]). These bits are used to select the transmit load
impedance. These must be set to match the cable impedance. Even if the Internal load impedance is turned off (via
TIMPTOFF); the external cable impedance has to be specified for optimum operation. For J1 applications, use
110Ω. See
Table 10-19.
Bits 2 to 0: Line Build-Out Select 2 to 0 (L[2:0])
. Used to select the transmit waveshape. The waveshape has a
voltage level and load impedance associated with it once the T1/J1 or E1 selection is made by settings in the
LTRCR register. See
Table 10-20.
Table 10-19. Transmit Load Impedance Selection
TIMPL1
TIMPLO
IMPEDANCE SELECTION
0
0
75
Ω
0
1
100
Ω
1
0
110Ω
1
1
120
Ω
Table 10-20. Transmit Pulse Shape Selection
L2 L1 L0 MODE IMPEDANCE
NOMINAL
VOLTAGE
0
0
0
E1
75Ω
2.37V
0
0
1
E1
120
Ω
3.0V
L2 L1 L0 MODE CABLE LENGTH
MAX
ALLOWED
CABLE LOSS
0
0
0
T1/J1
DSX-1/0dB CSU, 0ft–133ft ABAM 100
Ω
0.6dB
0
0
1
T1/J1
DSX-1, 133ft–266ft ABAM 100
Ω
1.2dB
0 1 0 T1/J1
DSX-1, 266ft–399ft ABAM 100
Ω
1.8dB
0
1
1
T1/J1
DSX-1, 399ft–533ft ABAM 100
Ω
2.4dB
1
0
0
T1/J1
DSX-1, 533ft–655ft ABAM 100
Ω
3.0dB
1
0
1
T1/J1
-7.5dB CSU
—
1
1
0
T1/J1
-15dB CSU
—
1
1
1
T1/J1
-22.5dB CSU
—