8.2.2.2 Detailed Design Procedure
See Dual Cable Driver Detailed Design Procedure and follow Steps 1 through 5. Refer to the additional steps below for distribution amplifier applications.
- Configure OUT0_SEL and SDI_OUT2_SEL pins according to the desired default use case.
- Tune the output VOD and de-emphasis level for the 100-Ω driver prior to each LMH1208 IN0±. In the distribution amplifier example shown in Figure 33, this step applies to the LMH1219 OUT0± driver and all LMH1208 OUT0± drivers that are daisy-chained to a subsequent LMH1208 IN0±. If OUT0± is located within 1-2 inches of IN0±, then use a lower VOD setting and no de-emphasis. If the OUT0± is located many inches away from IN0±, some VOD gain and de-emphasis may be required at OUT0± for the IN0 CTLE to equalize optimally. Use register control for more tuning options if necessary.
- Tune the SDI_VOD output amplitude control pin for optimal signal quality depending on the cable length attached at SDI_OUT1+ and SDI_OUT2+ for each LMH1208. Use register control for more tuning options, if necessary.