proton
Member level 3
Dear friends, I need your advice on a problem to which I'm working:
I need to send 9 signals from one board to another. These are digital
signals, asynchronous one to the other, with a pulse of about 100 ns
every 1 ms or so. The application is supposed to use as less power and
weight in the cabling as possible (it is intended for space use). The distance from one board to the other is about 1.5 meters ( ~ 6 feet) and
around there will be many electronic crates, so some crosstalk from the
environment is expected.
These are the possibilities to which I'm thinking :
1) 9 wires ribbon cable + 1 ground wire , single ended TTL or CMOS
driver and receiver with series termination at the source (don't know
how many ohms because the cable is not an obvious transmission line)
2) Same as before but using 9 wires + 9 grounds in twisted pair
(more weight). In this case the resistor is Rs = 100 - driver out z
3) Same as 1, but using and RC termination at the load (AC termination)
4) Again 18 wires (9 twisted pair couples, with 9 grounds) + RC
termination at the load
5) LVDS connection: 9 twitsted pair couples (more weight) and about
5 ma/ channel at the driver and 3 ma at the receiver (is this extimate
correct ???) steady all the time. In this case the termination would be
100 ohm resistor at the load as usual.
This seems the good solution, but
please remember that the signal has a very low duty cycle, so to
save power this is not the perfect solution, and besides needs by law
18 wires (weight issue)
Which one would you choose ?
thanks a lot for your help and happy new year
proton
I need to send 9 signals from one board to another. These are digital
signals, asynchronous one to the other, with a pulse of about 100 ns
every 1 ms or so. The application is supposed to use as less power and
weight in the cabling as possible (it is intended for space use). The distance from one board to the other is about 1.5 meters ( ~ 6 feet) and
around there will be many electronic crates, so some crosstalk from the
environment is expected.
These are the possibilities to which I'm thinking :
1) 9 wires ribbon cable + 1 ground wire , single ended TTL or CMOS
driver and receiver with series termination at the source (don't know
how many ohms because the cable is not an obvious transmission line)
2) Same as before but using 9 wires + 9 grounds in twisted pair
(more weight). In this case the resistor is Rs = 100 - driver out z
3) Same as 1, but using and RC termination at the load (AC termination)
4) Again 18 wires (9 twisted pair couples, with 9 grounds) + RC
termination at the load
5) LVDS connection: 9 twitsted pair couples (more weight) and about
5 ma/ channel at the driver and 3 ma at the receiver (is this extimate
correct ???) steady all the time. In this case the termination would be
100 ohm resistor at the load as usual.
This seems the good solution, but
please remember that the signal has a very low duty cycle, so to
save power this is not the perfect solution, and besides needs by law
18 wires (weight issue)
Which one would you choose ?
thanks a lot for your help and happy new year
proton