TLK10031 Datasheet, PDF (49/146 Pages) Texas Instruments – TLK10031 Single-Channel XAUI/10GBASE-KR Transceiver

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TLK10031
SLLSEL3A – JULY 2015 – REVISED AUGUST 2015
The number of words in the FIFO (fifo_depth[2:0]) and the HIGH/LOW watermark levels (wmk_sel[1:0])
are set through MDIO register 01.8001, and determine the allowable difference between the write clock
and the read clock as well as the maximum packet size that can be processed without FIFO collision. At
these watermarks the drop and insert start respectively and must happen before it hits overflow/underflow
condition. Although the FIFO is supposed to never overflow/underflow given the average IPG, if it ever
happens the overflow/underflow indications signal the error to the MDIO interface and the FIFO is reset.
Note that the overflow/underflow status indications are latched high and cleared when read.
Table 7-11 shows XAUI CTC FIFO configuration and capabilities:
Table 7-11. XAUI CTC FIFO Configurations
11
15
18
28
16
10
13
20
28
16
1xx
32
01
10
23
28
16
00
6
27
28
16
11
11
14
20
12
011
24
10
9
16
20
12
0x
6
19
20
12
1x
7
10
13
8
010
16
0x
5
12
13
8
001
12
xx
5
8
9
6
000
8
Plain FIFO, No CTC
7
4
4
100KB 200KB 400KB 800KB
10
default
4
80KB 160KB 320KB 640KB
8
4
50KB 100KB 200KB 400KB
5
4
10KB 20KB 40KB 80KB
1
4
60KB 120KB 240KB 480KB
6
4
40KB 80KB 160KB 320KB
4
4
10KB 20KB 40KB 80KB
1
3
30KB 60KB 120KB 240KB
3
3
10KB 20KB 40KB 80KB
1
3
10KB 20KB 40KB 80KB
1
1
No limit on pkt size (needs 0 ppm to work)
NOTE
To support the max packet sizes as shown in Table 7-11, it is assumed that there are
enough IDLE columns in IPG for deletion. Below is one example:
Configure the FIFO to be 32-deep (fifo_depth[2:0] = 3’b1xx) and set the LOW/HIGH
Watermarks to 10/23 (wmk_sel[1:0] = 2’b01). If the write clock is faster than the read
clock by 200ppm, to support the max packet size of 100KB, a minimum of 5 removable
columns in IPG is required (either IDLE columns or Sequence ordered_sets). If there are
only 4 removable columns in IPG, the max packet size supported is dropped to 80KB. If
there are only 3 removable columns in IPG, the max packet size supported is dropped to
60KB, and so on. As a rule of thumb, one removable column in IPG corresponds to 10KB
at 400ppm, 20KB at 200ppm, 40KB at 100ppm, and 80KB at 50ppm
Figure 7-30 through Figure 7-40 illustrate XAUI CTC FIFO configuration and capabilities. The green region
(the middle of the FIFO fill level) indicates that the FIFO is operating stability without insertion or deletion.
The more green bars in the figure, the more clock wander it can tolerate. The more yellow bars in the
figure, the bigger packet size it can support.
Copyright © 2015, Texas Instruments Incorporated
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