Hi all

can anybody tell me what is the difference between Zener Barrier, Isolator, Isolation amplifier.

which one to be used for Analog, which one for Digital inputs, digital outputs, analog outputs and for 4 wire connection

thanks
pandu

 

Pandu:

A Zener barrier does not isolate, but clamps voltage and current levels such that "dangerous" levels of energy can not pass from the control equipment area (safe) to the plant (where there is an explosion hazard).

"Isolator" can mean a multitude of things, but from the way you have framed the question I think you are talking about digital isolators. These use an air gap to allow a digital (information) signal to pass from one area to another, without the two sides being electrically connected (at least at DC). Often they are optical, sometimes transformers, occasionally capacitive.

Isolation amplifiers perform a similar service for analog (continuously variable) signals, and all three techniques used in digital isolators are also used in these. The analog signal can be converted to digital, transmitted across the barrier, then converted back to analog. Or it can be modulated to cross the barrier, then demodulated at the far side. Some signals also use matched analog opto- isolators, with distortion in the forward path being cancelled by matched distortion in a feedback path.

 

Pandu:

This article may help: http://www.ecnmag.com/article/hardware-corner-anatomy-digital-isolator/