Honored Contributor
Honored ContributorHi, thanks for the replies. I came across the 2 KDB's before, and it makes perfect sense. My only confusion is with the failsafe pullups in the buffer. Basically, as far as the actual differential driver and the receiver goes, the common mode of the Arria V device and differential levels are well within the spec of the receiver.
My concern was really just about the point at which the Arria V enables the LVDS output. On power up the TI buffer will be pulled up as the Arria V ouputs will be high impedance until it is configured and the LVDS outputs are enabled. At this moment the lines will be very weakly pulled to 3.3V by the buffer's 300k resistors. Obviously the low impedance LVDS driver of the Arria V will drive its desired common mode voltage when it is switched on, and overcome these pullups. But at this moment of being switched on, there will be 3.3v at the Arria V device pins. My concern is whether this might cause any issues to the driver. the 3.3 v is well within the absolute maximum (3.6) of the device pins, but I don't know if there is any problem at all with the differential driver of the Arria V seeing 3.3v on the pin when it is switched on. This all seems unlikely that there will be any issues, but I'd rather not AC couple if this is not necessary. Thanks again!
