Galvanic isolation is required in many electronic circuits, whether in measurement technology or in field bus systems and other extensive wiring in production plants, in order to avoid potential differences with sometimes fatal effects. But it is also required in audio and video technology to avoid "hum loops", or in medical technology for safety reasons.
Transformers can only transmit alternating voltages and are not impulse-tolerant. Optocouplers, on the other hand, are much too slow for today's demands and, moreover, are not stable over time as far as insulation and transparency of the insulation material are concerned. Other capacitive, inductive or high-frequency couplings also have disadvantages compared to GMR and TMR.
Isoloop GMR and TMR data couplers are the faster, longer-lasting and higher isolation alternative to optocouplers.