SLXT973QC.A2

Manufacturer Part NumberSLXT973QC.A2
ManufacturerIntel
SLXT973QC.A2 datasheet
 


Specifications of SLXT973QC.A2

Lead Free Status / RoHS StatusNot Compliant  
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
Page 51
52
Page 52
53
Page 53
54
Page 54
55
Page 55
56
Page 56
57
Page 57
58
Page 58
59
Page 59
60
Page 60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
Page 54/88

Download datasheet (2Mb)Embed
PrevNext
LXT973 10/100 Mbps Dual-Port Fast Ethernet PHY Transceiver
8.1.1
Scrambler Seeding
Once the transmit data (or IDLE symbols) are properly encoded, they are scrambled to further
reduce EMI and to spread the power spectrum using an 11-bit scrambler seed. Five-seed bits are
determined by global PHY address, and six-seed bits are selected by the port number. One of the 11
bits must be a “1”.
8.1.2
Scrambler Bypass
The scrambler can be bypassed by setting Register bit 16.12 = 1. Scrambler Bypass is provided for
diagnostic and test support.
The descrambler cannot be bypassed. The 100BASE-TX receiver in the LXT973 will not converge
to unscrambled idle, so a descrambler bypass is useless.
8.1.3
100BASE-T Link Failure Criteria and Override
The LXT973 normally transmits 100Mbps data packets only if it detects the link is up, and
transmits only Idle symbols or FLP bursts if the link is not up. Setting Register bit 16.14 = 1
overrides this function, allowing the LXT973 to transmit data packets even when the link is down.
This feature is provided as a diagnostic tool. Note that auto-negotiation must be disabled to
transmit data packets in the absence of link. If auto-negotiation is enabled, the LXT973
automatically begins transmitting FLP bursts if the link goes down.
8.1.4
Baseline Wander Correction
The LXT973 provides a baseline wander correction function which makes the device robust under
all network operating conditions. The MLT3 coding scheme used in 100BASE-TX is by definition
“unbalanced”. This means that the DC average value of the signal voltage can “wander”
significantly over short time intervals (tenths of seconds). This wander can cause receiver errors,
particularly at long line lengths (160 meters). The exact characteristics of the wander are
completely data dependent. “Killer Packets” have been created that exhibit worst case baseline
wander characteristics. The LXT973 baseline wander correction characteristics allow the LXT973
to recover error-free data, even at long line lengths.
8.1.5
Programmable Tx Slew Rate
The LXT973 device supports a slew rate mechanism where one of four pre-selected slew rates can
be used, set either through the input pins or through Register 27.
Figure 19. 100BASE-TX Reception with no Errors
RXCLK
RXDV
RXD<3:0>
preamble SFD SFD DA
RXER
54
DA
DA
DA
CRC
CRC
CRC
CRC
Datasheet
Document #: 249426
Revision #: 002
Rev. Date: March 1, 2002