JPS57111714A - Integrated circuit - Google Patents

Abstract

PURPOSE:To facilitate the test of a circuit without increasing the number of terminals, by providing a frequency detecting means, which is connected to a clock signal input terminal, in a chip to detect the frequency of an input clock signal and by controlling the operation mode of the internal circuit by the detection output. CONSTITUTION:A clock signal 21 for normal operation is inputted from a clock signal input terminal 2 provided in a chip 1 of an integrated circuit and is distributed to respective circuits by a clock distributing circuit 3. Meanwhile, the clock signal is inputted to an integrating circuit 5 through a buffer circuit 4, and a waveform is sent to an integrating circuit 6 from the integrating circuit 5 only during the change of the waveform, and the signal sent from the integrating circuit 5 is integrated by the integrating circuit 6, and a higher output level is inputted to a comparator 7 for a higher frequency of the input signal. A clock 22 for test of a low frequency is outputted by the input clock 21 for normal operation, thus facilitating the test of the circuit without increasing the number of terminals.