I have an Arduino Due that I am trying to use to drive 48 solid state relays. The solid state relays expect a 5 volt, 5 ma of control current. The max current draw would be ~240 ma. Since the Due is 3.3v I have attempted to use a level shifter to work around both the voltage and the current. The level shifter I am using is linked below. It is based on the 74LCX245 chip. I am not an electrical engineer so reading through some of these specs is a challenge. The level shifter is being powered by a separate 5v power supply from the Due. My project seems to be working just fine, my question is if the level shifter is isolating and protecting the Due from these large current loads?
When a DUE is powered via external power supply from the jack, the maximum total current you can draw is 800mA (500 mA is safer).
Well, if you have connected the level shifter so, it will be the level shifter that supplies the current to the output devices, so there should be no load (CMOS inputs are pretty much only a capacitive load) to the DUE microprocessor.
It is more a matter of the ability of the voltage converter(s) to provide the current to the 5V pin.
Your choice of a level shifter is a good one, it has a logic 1 threshold at 1.7V (about mid 3.3) and a 5 volt output. The solid state relays do the isolation for you that is one of there primary functions. Check the input rating of the solid state relays, the ones I use are good to 3 volts and are optically isolated. Your relays require 240mA at 5V for control. If I understand you are getting 5V from the on board regulator of the Due you may cause it to overheat and shut down. I would use a separate 5V supply. If you are using 24V or less consider a buck regulator for the 5
Luck & Have Fun!