32
Lucent Technologies Inc.
T7630 Dual T1/E1 5.0 V Short-Haul Terminator (Terminator-II)
Preliminary Data Sheet
October 2000
Line Interface Unit: Transmit
Output Pulse Generation
The line interface transmitter accepts a line rate clock
and NRZ data in single-rail mode (DUAL = 0) or posi-
tive and negative NRZ data in dual-rail mode (DUAL =
1) from the transmit framer unit or, optionally, the sys-
tem interface. The line interface transmitter converts
this data to a balanced bipolar signal (AMI format) with
optional B8ZS(DS1)/HDB3(E1) encoding and optional
jitter attenuation. Low-impedance output drivers pro-
duce the line transmit pulses. Positive ones are output
as positive pulses on TTIP and negative ones are out-
put as positive pulses on TRING. Binary zeros are con-
verted to null pulses.
In DSX-1 applications, transmit pulse shaping is con-
trolled by the on-chip pulse-width controller and pulse
equalizer. The pulse-width controller produces high-
speed timing signals to accurately control the transmit
pulse widths. This eliminates the need for a tightly con-
trolled transmit clock duty cycle that is usually required
in discrete implementations. The pulse equalizer con-
trols the amplitudes and shapes of the pulses. Different
pulse equalizations are selected through settings of
EQ2, EQ1, and EQ0 bits (register LIU_REG6, bits 0 to
2) as described in Table 7, Transmit Line Interface
Short-Haul Equalizer/Rate Control
below.
The reset default state of the equalization bits EQ2,
EQ1, and EQ0 can be predetermined by setting the
DS1_CEPT pin. The default transmit equalization is
EQ2, EQ1, and EQ0 = 000 (0 dB T1/DS1) when
DS1_CEPT = 1; EQ2, EQ1, and EQ0 = 110 (CEPT 120
/75
) when DS1_CEPT = 0. This feature aids in
transmitting AIS at the correct rate upon completion of
hardware reset; See LIU transmitter alarm indication
signal generator (XLAIS) on Table 33.
Table 7.
Transmit Line Interface Short-Haul Equalizer/Rate Control
* In DS1 mode, the distance to the DSX for 22-Gauge PIC (ABAM) cable is specified. Use the maximum cable loss figures for other cable types.
In CEPT mode, equalization is specified for coaxial or twisted-pair cable.
Reset default state is EQ2, EQ1, and EQ0 = 000 when pin DS1_CEPT = 1 and EQ2, EQ1, and EQ0 = 110 when pin DS1_CEPT = 0.
Loss measured at 772 kHz.
§ In 75
applications, Option 1 is recommended over Option 2 for lower LIU power dissipation. Option 2 allows for the use of the same trans-
former as in CEPT 120
applications (see Line Interface Unit: Line Circuitry section).
Short-Haul Applications
EQ2
EQ1
EQ0
Service
Clock Rate
Transmitter Equalization
*
Maximum
Cable Loss to
DSX
Feet
Meters
dB
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
DSX-1
1.544 MHz
0 to 131
131 to 262
262 to 393
393 to 524
524 to 655
0 to 40
40 to 80
80 to 120
120 to 160
160 to 200
0.6
1.2
1.8
2.4
3.0
CEPT
§
2.048 MHz
75
(Option 2)
120
or 75
(Option 1)
Not Used
—