Banana Jack wrote:So can you confirm the datasheet is wrong? Are there any Netonix switches available which can push 1A at 24V or should we re-think the topology? Thanks for your advice.
We rate our ports as follows:
24V and 48V @ .75A "constant" draw with spikes up to 1A over 2 pair in an environment of 55C. If the switch is in a cooler environment it will push 1A or more but that the limit of the Ethernet Transformer which is 1A per pair (keep in mind 1A positive on 1 pair and 1A negative on the other pair). In fact I am unaware of "any" Ethernet Transformer rated at more than 1A per pair and we have looked a lot no one makes one.
24VH and 48VH @ 1.5A "constant" draw with spikes up to 2A spread across 4 pair in an environment of 55C. If the switch is in a cooler environment it will push 2A spread across 4 pair (2A of positive, 1A per pair on 2 pair, and 2A of negative, 1A per pair on 2 pair) but again that is the limit of the Ethernet Transformer of 1A per pair.
Since we use Polyfuses to protect against fire in the event of shorts but the Polyfuse are affected by temperature it takes more current in cooler temps to open up the circuit and they are "slow" which is why the Polyfuse works fine to protect against fires it does little to protect the switch itself from shorts and a shorted cable can damage the switch as it fried the Transformer and sometimes depending on how the Transformer fries it sometimes damages the switch core.
So in reality our switch will deliver more current per port than the Ethernet Transformer center tap can handle we simply rate it @ .75A per pair "constant" draw because if the switch is setting in an environment of 55 C which is HOT the polyfuse is sized to pass .75A at that temperature.
