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Hi everyone,
I'm planning the wiring for a large addressable LED setup powered across several separate 5V power supplies (around 1500W total). The power supplies are within 4 meters from each other and share the same AC mains feed with their metal chassis grounded to earth, but their DC outputs are currently separate.
I'm trying to figure out the cleanest, safest way to distribute data from a single central controller to all strips without running into ground loops or signal integrity issues. I'd really appreciate some feedback on the trade-offs between the following approaches or other guidance into alternatives I didn't consider.
Level shifters (data + ground)
Given the relatively short distance, the simplest route is driving 5V TTL data alongside a ground wire over cat5 to each strip, however I have a few concerns. Running a ground wire from every strip back to the controller ties all the different PSU ground rails together through thin ethernet conductors. If there is any voltage drop or ground bounce between the supplies under load, return currents might try to route through those signal ground wires. If a main DC ground connection to a strip were to work loose or fail, wouldn't the entire load current for that zone try to return through the thin ethernet ground wire back to another PSU and cause a fire hazard?
Differential signaling (RS-422)
To keep the signal completely independent of heavy return currents, I considered using differential RS-422 drivers like so:
The controller board outputs differential pairs over standard cat5 cables and a single external reference wire carries the controller digital ground (CTRL_GND) alongside the ethernet bundle. Passive boards then take each RJ45 cable and the shared CTRL_GND line and split them into individual 3 wire channels (differential A, differential B, and CTRL_GND). At each strip input is a small board powered locally by that strip's power supply (+5V and LOCAL_GND). On it, the incoming CTRL_GND line connects to the strip's LOCAL_GND through a 100Ω series resistor to establish a shared reference without creating a hard DC short between supplies, and an RS-422 receiver IC decodes the differential pair into 5V TTL directly into the first pixel.
Is the RS-422 + 100Ω ground reference resistor approach a good solution for handling floating supplies or am I overcomplicating this? Would simply bonding all the PSU DC grounds together with heavy wire and using standard level shifters be reliable enough?
Or generally, what is the standard/best practice for this kind of multi PSU setup?
Thanks in advance for any insights or suggestions!
I'm planning the wiring for a large addressable LED setup powered across several separate 5V power supplies (around 1500W total). The power supplies are within 4 meters from each other and share the same AC mains feed with their metal chassis grounded to earth, but their DC outputs are currently separate.
I'm trying to figure out the cleanest, safest way to distribute data from a single central controller to all strips without running into ground loops or signal integrity issues. I'd really appreciate some feedback on the trade-offs between the following approaches or other guidance into alternatives I didn't consider.
Level shifters (data + ground)
Given the relatively short distance, the simplest route is driving 5V TTL data alongside a ground wire over cat5 to each strip, however I have a few concerns. Running a ground wire from every strip back to the controller ties all the different PSU ground rails together through thin ethernet conductors. If there is any voltage drop or ground bounce between the supplies under load, return currents might try to route through those signal ground wires. If a main DC ground connection to a strip were to work loose or fail, wouldn't the entire load current for that zone try to return through the thin ethernet ground wire back to another PSU and cause a fire hazard?
Differential signaling (RS-422)
To keep the signal completely independent of heavy return currents, I considered using differential RS-422 drivers like so:
The controller board outputs differential pairs over standard cat5 cables and a single external reference wire carries the controller digital ground (CTRL_GND) alongside the ethernet bundle. Passive boards then take each RJ45 cable and the shared CTRL_GND line and split them into individual 3 wire channels (differential A, differential B, and CTRL_GND). At each strip input is a small board powered locally by that strip's power supply (+5V and LOCAL_GND). On it, the incoming CTRL_GND line connects to the strip's LOCAL_GND through a 100Ω series resistor to establish a shared reference without creating a hard DC short between supplies, and an RS-422 receiver IC decodes the differential pair into 5V TTL directly into the first pixel.
Is the RS-422 + 100Ω ground reference resistor approach a good solution for handling floating supplies or am I overcomplicating this? Would simply bonding all the PSU DC grounds together with heavy wire and using standard level shifters be reliable enough?
Or generally, what is the standard/best practice for this kind of multi PSU setup?
Thanks in advance for any insights or suggestions!
