Hi,
Our application requires a 250 Mbps link onto 75 ohm co-ax and 100 ohm cat-5e transmission lines through a rotating joint. The loss through the rotating joint requires more than the standard 400 mV driven onto the line to ensure a good link, and the DS15BA101 looks promising. Because of the unexpected loss characteristics of the rotating joint, we do not intend to use the DS15EA101 sister part, and the length of the line does not require it.
1. Is the DS15BA101 good for driving 800mV single ended outputs into a transformer-coupled100 ohm differential cable with Rvo = 487 ohms and 50 ohm pull ups? The data sheet only details 400 mV single ended operation onto 100 ohm differential cable.
2. If we drive the line as above, is the supply current increase around 2.7mA over the data sheet? (Second output now drives 50 ohms in parallel with 150 ohms instead of just 50 ohms for 800mV single ended into co-ax)
3. If we use a transformer for common mode rejection instead of capacitors, will the CML outputs over-current in the DC state? They will effectively see a 25 ohm pull-up (DC) as the transformer will appear as a short circuit - possibly breaching the 28mA absolute maximum rating if the drivers maintain their output voltage.
4. Is the DS15BA101 good for driving 800mV into a 75 ohm transformer coupled co-ax? What Rvo and pull-up resistor values should be used? I'd guess at 720 ohms and 75 ohms.
Best regards
Andrew
