SEMICONDUCTOR INTEGRATED CIRCUIT

摘要

PURPOSE:To offer a flexible semiconductor integrated circuit, and to decrease the number of parts of an applied system by dynamically deciding the selective potential of a selective outside signal at the time of applying a power source. CONSTITUTION:The power source is applied, the potential of an A point rises at the time constants of a C1 and an R1, and it rises until the threshold voltage of an XOR gate XOR1. Then, the gate XOR1 is inverted, the voltage of a C point is turned to H, the gates G1 and G2 of a latch circuit 2 are opened, selec tive outside signal CS, that is, the potential of a D point is set in the circuit 2, and outputted to an E point. Then, the potential of a B point rises at the time constant larger than the A point, decided by a C1 and R2, and it rises beyond the threshold value of the gate XOR1. At that time, the gate XOR 1 is again inverted, and the gate of the circuit 2 is closed. After this, the voltage of the E point is held by the circuit 2. When the potential different from that at the time of applying the power source, that is, a selective potential is added to a D point, that is, a signal CS, an XOR gate XOR2 connected with the D point and the E point is inverted, and an F point, that is, a CSO being a selec tive signal to an inside circuit rises to an H potential. Thus, this circuit can be flexible, and the number of parts of the applied system can be decreased.