XRT72L50 Datasheet, PDF (305/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

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XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
FIGURE 118. INTERFACING THE XRT72L50 FRAMER IC TO THE XRT73L00 DS3/E3/STS-1 LIU
TxS E R
TxIn C lk
TxFram e
NIBBLEINTF
RESETB
INTB
CSB
RW
DS
AS
INTB
A[8:0]
D[7:0]
VDD
R xS er
R xC lk
RxFram e
R xL O S
R xO O F
R xR E D
R xA IS
U1
45
43
TxS er/S n d M sg
TxInCl
61 k
TxFram e
25
N ib In tf
28
Reset
13
8 ^Int
7 ^CS
10 ^{W R_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
M O TO
86
88 ^RxSer/RxIdle
90 ^RxClk
RxFram e
95
94 ^RxLOS
93 ^RxOOF
87 ^RxRed
R xA IS
XRT72L50
65
TxP O S
64
TxN E G
63
TxL in eC lk
79
DMO
78
E xtL O S
77
RLOL
69
LLOOP
70
RLOOP
68
TA O S
67
TxLev
66
E n c oD is
71
Req
76
R xP O S
75
R xN E G
74
R xL in eC lk
U2
37
TPDATA
38
TNDATA
36
TCLK
4
DMO
24
RLOS
23
RLOL
14
LLB
15
RLB
2
TA O S
1
TxL E V
21
E N C O D IS
12
R E Q D IS
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
5.3.1.2.1
AMI Decoding
AMI or Alternate Mark Inversion, means that consecutive "one's" pulses (or marks) will be of opposite polarity
with respect to each other. This line code involves the use of three different amplitude levels: +1, 0, and -1.
The +1 and -1 amplitude signals are used to represent one's (or mark) pulses and the "0" amplitude pulses (or
the absence of a pulse) are used to represent zeros (or space) pulses. The general rule for AMI is: if a given
mark pulse is of positive polarity, then the very next mark pulse will be of negative polarity and vice versa. This
alternating-polarity relationship exists between two consecutive mark pulses, independent of the number of
zeros that exist between these two pulses. Figure 119 presents an illustration of the AMI Line Code as would
appear at the RxPOS and RxNEG pins of the Framer, as well as the output signal on the line.
FIGURE 119. ILLUSTRATION OF AMI LINE CODE
Data 1 0 1 1 0 0 0 1 0 1 1 1 1 0 1 1 0 1 1 0 0 1 1 0 0 0 0 1
Line Signal
RxPOS
RxNEG
NOTE: One of the reasons that the AMI Line Code has been chosen for driving copper medium, isolated via transformers,
is that this line code has no dc component, thereby eliminating dc distortion in the line.
5.3.1.2.2
HDB3 Decoding
The Transmit E3 LIU Interface block and the associated LIU embed and combine the data and clocking
information into the line signal that is transmitted to the remote terminal equipment. The remote terminal
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