XR72L52 Datasheet, PDF (407/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
XRT72L52
REV. 1.0.1
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
be reliably received by the far-end receiver. Figure 166 presents a circuit drawing depicting the Framer IC in-
terfacing to an LIU (XRT73L00 DS3/E3/STS-1 Transmit LIU).
FIGURE 166. INTERFACING THE XRT72L52 FRAMER IC TO THE XRT73L00 DS3/E3/STS-1 LIU
TxSER
TxInClk
TxFrame
NIBBLEINTF
RESETB
INTB
CSB
RW
DS
AS
INTB
A[8:0]
D[7:0]
VDD
RxSer
RxClk
RxFrame
RxLOS
RxOOF
RxRED
RxAIS
U1
45
43
TxSer/SndMsg
61 ^TxInClk
TxFrame
25
NibIntf
28
Reset
13
8 ^Int
7 ^CS
10 ^WR_R/W
9 ^RD_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/RxIdle
90 ^RxClk
RxFrame
95
94 ^RxLOS
93 ^RxOOF
87 ^RxRed
RxAIS
XRT72L50
65
TxPOS
64
TxNEG
63
TxLineClk
79
DMO
78
ExtLOS
77
RLOL
69
LLOOP
70
RLOOP
68
TAOS
67
TxLev
66
EncoDis
71
Req
76
RxPOS
75
RxNEG
74
RxLineClk
U2
37
TPDATA
38
TNDATA
36
TCLK
4
DMO
24
RLOS
23
RLOL
14
LLB
15
RLB
2
TAOS
1
TxLEV
21
ENCODIS
12
REQDIS
33
RPOS
32
RNEG
31
RCLK1
XRT73L00
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 XRT72L52 contains a block which is known as the Transmit E3 LIU Interface
block. The purpose of the Transmit E3 LIU Interface block is to take the Outbound E3 data stream, from the
Transmit E3 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. HDB3 (High Density Bipolar - 3)
2. And to transmit this data to the LIU IC.
Figure 167 presents a simple illustration of the Transmit E3 LIU Interface block.
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