Does inductive or capacitive coupling have an advantage over the other method in terms of EMI sensitivity?
Asked by: Don
First I want to be clear that there is EMI, which we will categorize as directly coupled fields, either radiated or received, and EMC we treat as conducted noise and transients. There is also cross coupling between these, where external fields couple to wires and PCB traces creates EMC type noise.
EMI sensitivity is pretty low for all of the technologies due to their size compared to the wavelength of external disturbances. However once the noise is on the board as high frequency noise or as high voltage transients causing common mode voltage, there are differences.
Optocouplers and capacitive couplers tend ot be more sensitive to common mode transients (CMR) because they require sensitive receivers. Ground referenced pulse encoding schemes tend to be more sensitive to differential noise like on power supply disruptions. It It is more a function of the encoding scheme than the inductive or capacitive choice. More robustness can be built in, but almost always with a cost in power. We feel that the ADuM144x and ADuM124x strike a good balance.
Retrieving data ...