Parasitic power and an LTC490 as DMX (RS485) bus repeater
Unlikely to be accepable, DMX permits a total load on the line of 32 unit loads where an RS485 unit is a 15k resistor to -3V or 5V and the LTC490 could draw more current than that, depending on its load. Although the datasheet quotes the supply current as only 500uA max, that is on no load and it could be up to 250mA if driving into a short circuit.