Large scale integrated circuit device for switching oscillation circuit

摘要

An integrated circuit device having a CR oscillation circuit and a crystal oscillation circuit and capable of selecting either the CR oscillation circuit or the crystal oscillation circuit, includes a unit for receiving an electrical signal, and a unit for selecting either the CR oscillation circuit or the crystal oscillation circuit in accordance with a state of the electrical signal received by the receiving unit. The integrated circuit device also includes a unit for holding the receiving unit at a predetermined level of the electrical signal. The holding unit is adapted to hold the receiving unit at the predetermined level in accordance with a state of the receiving unit. The receiving unit is a selection terminal and the selecting unit is a selection circuit. The selection circuit includes a first analog switch and a second analog switch for controlling the crystal oscillation circuit, and an OR gate for controlling a selection of either the CR oscillation circuit or the crystal oscillation circuit in accordance with the electrical signal received at the selection terminal.