
XRT72L54
FOUR CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
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PRELIMINARY
REV. P1.1.2
191
The XRT72L54 Framer IC is a digital device that
takes DS3 payload and overhead bit information from
some terminal equipment, processes this data and ul-
timately, multiplexes this information into a series of
outbound DS3 frames. However, for DS3 coaxial ca-
ble applications, the XRT72L54 Framer IC lacks the
current drive capability to be able to directly transmit
this DS3 data stream through some transformer-cou-
pled coax cable with enough signal strength for it to
comply with the Isolated Pulse Template require-
ments and be received by the remote receiver.
Therefore, in order to get around this problem, the
Framer IC requires the use of an LIU (Line Interface
Unit) IC. An LIU is a device that has sufficient drive
capability, along with the necessary pulse-shaping
circuitry to be able to transmit a signal through the
transmission medium in a manner that it can (1) com-
ply with the DSX-3 Isolated Pulse Template require-
ments and (2) be reliably received by the Remote Ter-
minal Equipment.
Figure 65 presents a circuit draw-
ing depicting the Framer IC interfacing to an LIU
(XRT7300 DS3/E3/STS-1 Transmit LIU).
The Transmit Section of the XRT72L54 contains a
block which is known as the Transmit DS3 LIU Inter-
face block. The purpose of the Transmit DS3 LIU In-
terface block is to take the outbound DS3 data
stream, from the Transmit DS3 Framer block, and to
do the following:
1. Encode this data into one of the following line
codes
a. Unipolar (e.g., Single-Rail)
b. AMI (Alternate Mark Inversion)
c. B3ZS (Bipolar 3 Zero Substitution)
2. And to transmit this data to the LIU IC.
Figure 66 presents a simple illustration of the Trans-
mit DS3 LIU Interface block.
FIGURE 65. APPROACH TO INTERFACING THE XRT72L54 FRAMER IC TO THE XRT73L04 DS3/E3/STS-1 TRANS-
MITTER
LIU (ONE CHANNEL SHOWN)
R6
270
XRT71D04_CS* (Optional)
Rx_OOF_Ch_0
RxSERIAL_CLK_0
R7
4.7k
RxAIS_Ch_0
ALE
T2
T3001
1
6
3
4
A[10:0]
U1
XRT72L54_Ch_0
C1
D1
E2
C9
D9
B8
C7
B7
C6
C3
B2
A5
F2
F3
F1
T20
T19
R20
P18
P19
P20
N18
N19
N20
M17
M18
L18
L20
K20
K19
K18
K17
J20
J19
J17
P17
V20
R18
R19
H20
E18
G4
E20
F19
D20
F20
C4
A3
B5
C5
T18
M19
M20
TxPOS_0
TxNEG_0
TxLineClk_0
DMO_0
ExtLOS_0
RLOL_0
LLOOP_0
RLOOP_0
TAOS_0
TxLEV_0
ENCODIS_0 (TxOFF_0)
REQB_0
RxPOS_0
RxNEG_0
RxLineClk_0
MOTO
RESETB
A0
A1
A2
A3
A4
A5
A6
A7
A8
D0
D1
D2
D3
D4
D5
D6
D7
Rdy_Dtck
WRB_RW
RDB_DS
CSB
ALE_AS
INT
TxSER_0
TxInClk_0
TxFrame_0
RxSer_0
RxClk_0
RxFrame_0
RxLOS_0
RxOOF_0
RxRED_0
RxAIS_0
NIBBLEINTF
A9
A10
U2
XRT73L04IV_Ch_0
47
49
34
32
80
79
35
36
61
60
59
41
40
42
78
58
73
54
64
65
66
131
75
52
33
31
69
70
71
72
110
TxAVDD0
TxAGND0
TTIP0
TRING0
RTIP0
RRING0
MTIP0
MRING0
RPOS0
RNEG0/LCV0
RCLK0
TPDATA_0
TNDATA_0
TCLK_0
RxAVDD0
RxDVDD0
RxAGND0
RxDGND0
RLOS_0
RLOL_0
EXCLK_0
TxOFF
LOSTHR_0
HOST/HW
TxAVDD0
TxAGND0
CS
SCLK
SDI
SDO
REG_RESET*
J2
BNC
1
2
R1
37.4
C2
0.01uF
RxFRAME_0
TxDATA_OUT_0
R5
270
XRT72L54_CS*
HW_RESET*
44.736MHz
R3
31.6
TxFRAME_0
R4
31.6
RxRED_ALARM_0
D[7:0]
RD*
READY_OUT*
RxAVDD_0
C4
0.01uF
TxAVDD_0
R2
37.4
T1
T3001
1
6
3
4
RxDATA_IN_0
C1
0.01uF
WR*
C3
0.01uF
Rx_LOS_Ch_0
DVDD_0
J1
BNC
1
2
C5
0.01uF
XRT72L54_INT*