XRT72L50 Datasheet, PDF (202/471 Pages) Exar Corporation – SINGLE CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L50
SINGLE CHANNEL DS3/E3 FRAMER WITH HDLC CONTROLLER
REV. 1.2.1
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FIGURE 63. IINTERFACING 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
61
TxIn C lk
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
R xC lk
RxFram e
95 RxLO
94
S
93 ^RxOOF
87
RxRed
R xA I
S
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
4.3.1.2.1
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 the AMI line code
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 64 presents an illustration of the AMI Line Code
as would appear at the RxPOS and RxNEG input pins of the Framer, as well as the corresponding output
signal on the line.
FIGURE 64. 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.
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