Protection: How Much is Enough for An Analog Output?

Abstract: Analog outputs drive motors and actuators in factories and plants. They are the final control step in programmable logic controllers (PLC). The output amplifiers typically drive 0 to 10V and 4 to 20mA circuits. They need protection from high-voltage motor faults, electrostatic discharge (ESD), electromagnetic interference (EMI), electromagnetic susceptibility (EMS), and radio frequency interference (RFI). Many circuits are suggested to meet the application requirements.