I'm using LTC1474 in an industrial aplication that I would like to discuss. The main ideia is to generate DC supply to a industrial equipment from a 4-20mA current source. In this application, diferent from pressure transmitter for example, the equipment receives a 4-20mA signal from a PLC current outpout module.
I saw on LTC1474 datasheet a circuit that already do this (figure 11, page 14), however, the point is that the circuit input should be HART compatible. Based on HART specifications, this kind of equipment must have an input impedance of 230 to 600 ohms, and using a zener of 12V on circuit input gives me values higher than 600 ohms for 20.8mA.
Does anyone face this kind of issue for HART based actuators?
For HART communication, we are using AD5700.
Thanks in advance.