PURPOSE:To prevent an abnormal current from that may occur immediately after the turning on of a power source by inactivating a chip activating signal inside a chip for a determined time following the turning on the power source. CONSTITUTION:At a moment immediately after the rising of a power supply voltage, the nodes A, A' of a CR circuit constituted of a capacitor C and a resistor R is in a low level. Then, the capacitor C is charged through the resistor R, and until a time when this voltage exceeds the threshold of a waveform shaping circuit G1, and output Q from an order circuit consisting of a NAND gate G2 and an OR gate G keeps its being in a high level regardless of the input level the inverse of a raw address strobing signal RAS. Accordingly, for such a period as corresponding to the capacitor C, the resistor R, and the threshold of the circuit G1, chip activating signals are automatically inactivated, hence an abnormal current immediately after the turning on of the power source can be prevented.
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