It is possible to implement 4-20mA current loop using PSoC. Either PSoC3/ PSoC5LP device can be used for this application. Please refer the below links for more information:
Thank you for your reply, but I think that the question here is not how to make a 4-20 output loop from PSOC,
I would also like to know that if it is possible to run any of the Psoc ( 1,3,4,5) that would use some excitation current to determine resistance in sensor, using 5v and current consumption less than 3mA ?
because above that, it would be violating the current limit and would start interfering with 4-20mA signal in a strict 2 wire transmitter application.
I have tried to make same project using psoc1 and 4 and so far it has not been working because both of the family are drawing more than 20mA current from the loop.