INPUT DEVICE OF PORTABLE DEVICE AND PORTABLE DEVICE USING THE SAME, AND OPERATION METHOD THEREOF

摘要

PURPOSE: An input device of a mobile terminal is provided to reduce the number of ports that are allocated to a keypad and to distinguish an input signal which is allocated to each key. CONSTITUTION: A plurality of resistors is allocated to a key column(125) based on a switch that is connected to a basic resistance. A reference voltage unit(127) is connected to the basic resistance. The reference voltage unit offers the reference voltage. A first comparator and a second comparator distribute the reference voltage by one resistance that is connected to an activated switch. The first comparator and the second comparator receive an analog key input signal corresponding to the distributed reference voltage.