XRT72L53 Datasheet, PDF (193/467 Pages) Exar Corporation – THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L53
REV. P1.1.7
THREE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
áç
PRELIMINARY
The XRT72L53 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 XRT72L53 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).
FIGURE 65. APPROACH TO INTERFACING THE XRT72L53 FRAMER IC TO THE XRT73L03 DS3/E3/STS-1 TRANS-
MITTER LIU (ONE CHANNEL SHOWN)
TxSER
TxInClk
TxFrame
NIBBLEINTF
RESETB
INTB
CSB
RW
DS
AS
INTB
A[8:0]
D[7:0]
5V
RxSer
RxClk
RxFrame
RxLOS
RxOOF
RxRED
RxAIS
U1
46
43 ^TxSER
61 ^TxInClk
TxFrame
25
NIBBLEINTF
28
RESETB
13
8
7
10
INTB
CSB
WRB_RW
9 ^RDB_DS
6 ^ALE_AS
Rdy_Dtck
15
16 ^A0
17 ^A1
18 ^A2
19 ^A3
20 ^A4
21 ^A5
22 ^A6
23 ^A7
A8
32
33 ^D0
34 ^D1
35 ^D2
36 ^D3
37 ^D4
38 ^D5
39 ^D6
D7
27
MOTO
86
88 ^RxSer
90 ^RxClk
RxFrame
95
94 ^RxLOS
93 ^RxOOF
87
RxRED
RxAIS
XRT72L5x
TxPOS
TxNEG
TxLineClk
DMO
ExtLOS
RLOL
LLOOP
RLOOP
TAOS
TxLEV
ENCODIS
REQB
RxPOS
RxNEG
RxLineClk
U2
TPDATA
TNDATA
TCLK
DMO
RLOS
RLOL
LLB
RLB
TAOS
TxLEV
ENCODIS
REQDIS
33 _RPOS
32
RNEG
31
RCLK1
XRT73L0x
41
TTIP
40
TRING
44
MTIP
43
MRING
1 ^R3 2
270
1 ^R4 2
270
R1
1
2
36
1 ^T1 5
R2
1
2
36
4
8
1:1
TTIP
TRING
8
RTIP
9
RRING
C1
1
2
0.01uF
R5
37.5
R6
37.5
1 ^T2 5
4
8
1:1
RTIP
RRING
The Transmit Section of the XRT72L53 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.
193