M-LVDS connectors for multidrop topology

[johnkaz77]

Hi everyone! In my system I wil have one motherboard and ten daughterboards, but they won't be pinned onto the motherboard, the communication between the master(motherboard) and the slaves (daughterboards) will be done through cables. Are there any cables and connectors for multidrop topology that can support M-LVDS signals for data rates up to 20Mbps? The maximum distance is 40 cm. Thank you.

 

[barry]

CAT 5 cable is good up to 100MHz. Look at cable manufacturer's data-you might be able to use some other shielded/twisted pair cable.

 

[FvM]

You'll preferably implement a feedthrough topology with send and return pairs in every cable. Connector selection isn't that critical at 20 MBPS, cable impedance should be roughly 100 ohm differential, e.g. CAT5 cable.

 

[johnkaz77]

Thank you for your answer. I have a clock signal (M-LVDS signal as well) and i want to distribute it to 10 daughterboards through one twisted pair, what connectors can i use to form a T-connection? And also, could you suggest any appropriate connectors for the connection with the pcb for maximum signal integrity and minimal skew?

 

[barry]

Since you would need a custom cable to implement your "T", I would just daisy-chain the signals through the PCB and use COTS CAT5 cable with RJ-45 connectors. In other words, CLOCK_IN=1,2; CLOCK_OUT=3,4; DATA_IN=5,6, DATA_OUT=7,8. (Those pins aren't exactly right, because ethernet cables mixup the pairs, but you get the idea). You could also put receivers/drivers on each PCB, but I'm not sure that would be necessary at your speed and distance.