ISO1211: ISO1211 noise problem

Hi Mehmet,

ISO1211 does employ capacitive isolation but this doesn't mean input noise can pass through it. Between internal isolation cap and external terminal, there is a lot of circuit that accepts inputs, modulates input data and then transmits to the other side which then again gets demodulated to bring it back to original data form. Since it involves many steps for the input data to correctly reach the output, any signal that is not considered to be like data cannot pass through the isolation barrier easily.

If you have a high frequency noise at the input that is not hitting the HIGH/LOW threshold then it cannot pass through the isolation barrier. If you have noise at the input that is reaching HIGH/LOW thresholds, then there is no way to differentiate between data or noise and hence this will pass through.

You can use the TINA simulation tool itself to see how does the output look like when you add noise to ISO1211 input. The tool simulation should give good indication of how device responds to it.

I hope this answers your question, thanks.

Regards,
Koteshwar Rao