Team,
1) When using DS38EP100 on a backplane with a max trace length of 12" is there any benefit to using two of these devices - one on Rx side and one on Tx side - on each differential pair of the SGMII (LVDS) interface path?
2) Is there any danger of voltage spiking if either side is hotplugged into the system? If so, is the chip protected against that?
Thanks.
- Nate, AFA
Hello: Customer also is requesting app notes or white papers on designs like this as he has not dealt with this before.
Greetings -
The DS38EP100 is a passive equalizer for 1 Gbps to 5 Gbps differential links. Being passive, it can be placed at the start of the trace, in the middle, or at the end. Also, you can stack them, BUT being a "de-emhasis" function the signal is attenuated each time. Usually only one is used per link. The gain curve is shown in the data sheet. When used close to the MIN freq range, you will get strong attenuation of the signal. If your starting signal is large enough and the RX input level is still met, this could help to correct for loss and ISI. The datasheet includes some plots that show performance at 1.5G and how it can help extend longer reaches. I am not sure this is the best solution to the probelm you have described.
If you need to extend these LVDS-like signals (625MHz) over a shorter length - a LVDS buffer / repeater is more likely the solution to the problem. Perhaps the DS25BR1xx family offers a wider range of active LVDS buffering of signals with sigcon features option in the family.
John Goldie
DPS APPS / SVA