Patent ID: 7450726

Claim:
A device enabling a user to play an audio signal, said device comprising: a jack containing a plurality of connection points; and a detector circuit examining an impedance present between at least a pair of said plurality of connection points and determining whether a headset is present in said jack based on a value of said impedance; wherein said detector circuit measures a voltage between said pair of said plurality of connection points and determines that said headset is present if said voltage is low compared to a reference voltage; wherein said detector circuit comprises: a first node being coupled to receive a bias voltage, wherein said first node is coupled to one of said pair of connection points and wherein the other one of said pair of connection points is coupled to Vss, whereby said bias voltage is presented at said first node if said headset is not present and a low voltage is presented at said first node if said headset is present; and a comparator having a first input terminal and a second input terminal, said first input terminal being connected to said first node, said second input being connected to said reference voltage, wherein said reference voltage is generated as a fraction of said bias voltage, wherein said comparator generates a signal having a first logical value if said headset is present and having a second logical value otherwise; and wherein said reference voltage equals (7* said supply voltage /8), wherein ‘*’ represents multiplication operator and ‘/’ represents division operator.