XRT7250 Datasheet, PDF (305/463 Pages) Exar Corporation – DS3/E3 FRAMER IC

XRT7250
DS3/E3 FRAMER IC
REV. 1.1.1
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FIGURE 130. ILLUSTRATION ON HOW THE RECEIVE E3 FRAMER (WITHIN THE XRT7250 FRAMER IC) BEING INTER-
FACE TO THEXRT7300 LINE INTERFACE UNIT, WHILE THE FRAMER IS OPERATING IN BIPOLAR MODE
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
61
TxSER
TxInClk
TxFrame
25 _NIBBLEINTF
28 _RESETB
13
8
7
10
9
6
INTB
CSB
WRB_RW
RDB_DS
ALE_AS
Rdy_Dtck
15
16 ^A0
17 ^A1
18 ^A2
19
20
21
22
23
A3
A4
A5
A6
A7
A8
32
33
34
35
36
37
38
D0
D1
D2
D3
D4
D5
39 ^D6
D7
27
MOTO
86
88 ^RxSer
90
RxClk
RxFrame
95
94
93
87
RxLOS
RxOOF
RxRED
RxAIS
XRT7250
TxPOS ⁶⁵
TxNEG ⁶⁴
TxLineClk ⁶³
DMO ⁷⁹
ExtLOS ⁷⁸
RLOL ⁷⁷
69
LLOOP
70
RLOOP
TAOS ⁶⁸
TxLEV ⁶⁷
ENCODIS ⁶⁶
REQB ⁷¹
76
RxPOS
75
RxNEG
RxLineClk ⁷⁴
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
XRT7300
TTIP ⁴¹
TRING ⁴⁰
MTIP ⁴⁴
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
RRING ⁹
C1
12
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 consec-
utive "one's" pulses (or marks) will be of opposite po-
larity with respect to each other. This line code in-
volves 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" ampli-
tude 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 po-
larity and vice versa. This alternating-polarity rela-
tionship exists between two consecutive mark pulses,
independent of the number of zeros that exist be-
tween these two pulses. Figure 131 presents an illus-
tration 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 131. 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
formers, is that this line code has no dc component, thereby
been chosen for driving copper medium, isolated via trans- eliminating dc distortion in the line.
286