ZHCSKE8D March 2016 – October 2019 DS250DF410
PRODUCTION DATA.
The output differential voltage (VOD), pre-cursor, and post-cursor equalization of the driver is controlled by manipulating the FIR tap settings. The main cursor tap is the primary knob for amplitude adjustment. The pre- and post-cursor FIR tap settings can then be adjusted to provide equalization. To maintain a constant peak-to-peak VOD, the user should adjust the main cursor tap value relative to the pre- and post-cursor tap changes so as to maintain a constant absolute sum of the FIR tap values. The table below shows various settings for VOD settings ranging from 205 mVpp to 1225 mVpp (typical). Note that the output peak-to-peak amplitude is a function of the sum of the absolute values of the taps, whereas the low-frequency amplitude is purely a function of the main-cursor value.
FIR SETTINGS | Peak-to Peak VOD(V) | RPRE(dB) | RPST(dB) | ||
---|---|---|---|---|---|
PRE-CURSOR:
REG_0x3E[6:0] |
MAIN-CURSOR:
REG_0x3D[6:0] |
POST-CURSOR:
REG_0x3F[6:0] |
|||
0 | 0 | 0 | 0.205 | NA | NA |
0 | +1 | 0 | 0.260 | NA | NA |
0 | +2 | 0 | 0.305 | NA | NA |
0 | +3 | 0 | 0.355 | NA | NA |
0 | +4 | 0 | 0.395 | NA | NA |
0 | +5 | 0 | 0.440 | NA | NA |
0 | +6 | 0 | 0.490 | NA | NA |
0 | +7 | 0 | 0.525 | NA | NA |
0 | +8 | 0 | 0.565 | NA | NA |
0 | +9 | 0 | 0.610 | NA | NA |
0 | +10 | 0 | 0.650 | NA | NA |
0 | +11 | 0 | 0.685 | NA | NA |
0 | +12 | 0 | 0.720 | NA | NA |
0 | +13 | 0 | 0.760 | NA | NA |
0 | +14 | 0 | 0.790 | NA | NA |
0 | +15 | 0 | 0.825 | NA | NA |
0 | +16 | 0 | 0.860 | NA | NA |
0 | +17 | 0 | 0.890 | NA | NA |
0 | +18 | 0 | 0.925 | NA | NA |
0 | +19 | 0 | 0.960 | NA | NA |
0 | +20 | 0 | 0.985 | NA | NA |
0 | +21 | 0 | 1.010 | NA | NA |
0 | +22 | 0 | 1.040 | NA | NA |
0 | +23 | 0 | 1.075 | NA | NA |
0 | +24 | 0 | 1.095 | NA | NA |
0 | +25 | 0 | 1.125 | NA | NA |
0 | +26 | 0 | 1.150 | NA | NA |
0 | +27 | 0 | 1.165 | NA | NA |
0 | +28 | 0 | 1.190 | NA | NA |
0 | +29 | 0 | 1.205 | NA | NA |
0 | +30 | 0 | 1.220 | NA | NA |
0 | +31 | 0 | 1.225 | NA | NA |
0 | +18 | -1 | 0.960 | NA | 2.1 |
0 | +17 | -2 | 0.960 | NA | 2.5 |
0 | +16 | -3 | 0.960 | NA | 3.1 |
0 | +15 | -4 | 0.960 | NA | 3.8 |
0 | +14 | -5 | 0.960 | NA | 4.7 |
0 | +13 | -6 | 0.960 | NA | 5.8 |
0 | +12 | -7 | 0.960 | NA | 7.2 |
0 | +11 | -8 | 0.960 | NA | 9.0 |
0 | +10 | -9 | 0.960 | NA | 11.6 |
-1 | 18 | 0 | 0.960 | 1.0 | NA |
-2 | 17 | 0 | 0.960 | 1.6 | NA |
-3 | 16 | 0 | 0.960 | 2.4 | NA |
-4 | 15 | 0 | 0.960 | 3.3 | NA |
0 | 26 | -1 | 1.165 | NA | 1.1 |
0 | 25 | -2 | 1.165 | NA | 1.3 |
0 | 24 | -3 | 1.165 | NA | 1.8 |
0 | 23 | -4 | 1.165 | NA | 2.2 |
0 | 22 | -5 | 1.165 | NA | 2.7 |
0 | 21 | -6 | 1.165 | NA | 3.3 |
0 | 20 | -7 | 1.165 | NA | 3.9 |
0 | 19 | -8 | 1.165 | NA | 4.7 |
0 | 18 | -9 | 1.165 | NA | 5.7 |
0 | 17 | -10 | 1.165 | NA | 6.9 |
0 | 16 | -11 | 1.165 | NA | 8.4 |
0 | 15 | -12 | 1.165 | NA | 10.1 |
-1 | 26 | 0 | 1.165 | 0.7 | NA |
-2 | 25 | 0 | 1.165 | 1.2 | NA |
-3 | 24 | 0 | 1.165 | 1.5 | NA |
-4 | 23 | 0 | 1.165 | 2.0 | NA |
-5 | 22 | 0 | 1.165 | 2.6 | NA |
-6 | 21 | 0 | 1.165 | 3.2 | NA |
-7 | 20 | 0 | 1.165 | 4.0 | NA |
The recommended pre-cursor and post-cursor settings for a given channel will depend on the channel characteristics (mainly insertion loss) as well as the equalization capabilities of the downstream receiver. The DS250DF410 receiver, with its highly-capable CTLE and DFE, does not require a significant amount of pre- or post-cursor. The figures below give general recommendations for pre- and post-cursor for different channel loss conditions. The insertion loss (IL) in these plots refers to the total loss between the link partner transmitter and the DS250DF410 receiver.