As I understand it, the VIIPro devices have on-chip differential termination resistors which can be brought into play by selecting the XXX_LVDS_25_DT buffers. I've looked at several designs using VIIPro devices from different manufacturers but they all seem to use external 100R resistors to achieve LVDS termination. Can anyone tell me why this would be the case please? I thought the reduction in component count would be very welcome. Is it because of heat dissipation?
TIA,
Rog.