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.
Figure 11. Guideline for Link Partner FIR Settings When IL ≤ 15 dB
Figure 12. Guideline for Link Partner FIR Settings When IL ≤ 25 dB
Figure 13. Guideline for Link Partner FIR Settings When IL ≤ 35 dB