US Patent 7248707 Detection circuit

A plug detection circuit. The detected circuit is disposed in an electronics device with an earphone jack, accepting plugs with a plurality of conductive rings. The detection circuit has a plurality of pins, wherein a first pin detects, and outputs a first logic potential, and a second pin detects the potentials at the conductive rings and outputs a second logic potential. The detection circuit determines the type of earphone connected to the earphone jack.