Is there any restriction (other than validation for operation by TI) on running either of these devices slower than 155 Mbps? Is the minimum spec due to hardware limitations (e.g., internal ac coupling of clocks) or is this only a validation issue (e.g., the part will theoretically work at 1 Mbps, but it is not validated to operate at that speed). I would like to use these devices at speeds from 1 Mbps to 10 Mbps - if possible should it be DC or AC coupled?