1. A floating detection circuit for detecting the floating state of an input node which can receive an externally applied DC signal, comprising: a pulse generator coupled to said input node, for supplying a pulse signal to the input node; a counter for receiving said pulse signal and counting the number of pulses included in the pulse signal during predetermined intervals; and a comparator for comparing the number of pulses with a predetermined reference number, so as to produce a floating detection signal, wherein said floating detection signal indicates whether or not the input node is in a floating state.