Datasheet

DS2148/DS21Q48
48 of 73
7.4 G.703 Synchronization Signal
The DS2148 is capable of receiving a 2.048MHz square-wave synchronization clock as specified in
Section 13 of ITU G.703 (10/98). To use the DS2148 in this mode, set the receive synchronization clock
enable (CCR5.3) = 1. The DS2148 can also transmit the 2.048MHz square-wave synchronization clock as
specified in Section 10 of G.703. To transmit the 2.048MHz clock, set the transmit synchronization clock
enable (CCR5.2) = 1.
Table 7-1. Line Build-Out Select for E1 in Register CCR4 (ETS = 0)
L2 L1 L0 V
DD
APPLICATION N RETURN LOSS Rt
0 0 0 5V
75Ω normal
1:1.36 N.M.
0Ω
0 0 1 5V
120Ω normal
1:1.36 N.M.
0Ω
1 0 0 5V
75Ω w/ high return loss
1:1.36 21dB
18Ω
1 0 1 5V
120Ω w/ high return loss
1:1.36 21dB
27Ω
N.M. = Not meaningful
Note: See Figure 7-1, Figure 7-2, and Figure 7-3.
Table 7-2. Line Build-Out Select for T1 in Register CCR4 (ETS = 1)
L2 L1 L0 V
DD
APPLICATION N RETURN LOSS Rt
0 0 0 5V
DSX-1 (0 to 133 feet) /
0dB CSU
1:1.36 N.M.
0Ω
0 0 1 5V
DSX-1 (133 to 266 feet)
1:1.36 N.M.
0Ω
0 1 0 5V
DSX-1 (266 to 399 feet)
1:1.36 N.M.
0Ω
0 1 1 5V
DSX-1 (399 to 533 feet)
1:1.36 N.M.
0Ω
1 0 0 5V
DSX-1 (533 to 655 feet)
1:1.36 N.M.
0Ω
1 0 1 5V
-7.5dB CSU
1:1.36 N.M.
0Ω
1 1 0 5V
-15dB CSU
1:1.36 N.M.
0Ω
1 1 1 5V
-22.5dB CSU
1:1.36 N.M.
0Ω
N.M. = Not meaningful
Note: See Figure 7-1, Figure 7-2, and Figure 7-3..
Table 7-3. Transformer Specifications for 5V Operation
SPECIFICATION RECOMMENDED VALUE
Turns Ratio 5V Applications 1:1(receive) and 1:1.36(transmit) ±2%
Primary Inductance
600µH minimum
Leakage Inductance
1.0µH maximum
Interwinding Capacitance 40pF maximum
Transmit Transformer DC Resistance
Primary (Device Side)
Secondary
1.2Ω maximum
1.2Ω maximum
Receive Transformer DC Resistance
Primary (Device Side)
Secondary
1.2Ω maximum
1.2Ω maximum