digital logic design

MrChips

Joined Oct 2, 2009
23,541
A "floating" circuit is unrelated to any particular voltage.
A "floating" circuit signifies that it is not connected and any reference voltage.
For example, a floating PSU means that the output terminals of the power supply are not referenced to EARTH ground. A battery is a floating power supply.

A "floating" input usually means that the input resistance is very high. In this case, this would mean that a tiny input current might induce any random unknown voltage at the input. Hence it is poor practice to leave an input pin "floating".
 
Top