| 摘要 |
PURPOSE:To perform automatic starting operation and test lower-limit voltage operation selectively when the power source is turned on by stopping the operation of the dummy cycle starting circuit of an automatic starting circuit forcibly with a signal from an external terminal. CONSTITUTION:When the chip select signal CS' from the external terminal goes up to a level higher than H which is used normally, an MOSFET47 with a high threshold value is turned on. Then an H output is impressed to close a NAND gate G, the transmission of timing pulses phi' for starting from the dummy cycle starting circuit of the automatic starting circuit consisting of the voltage dividing circuit composed of P channel MOSFETs Q45 and Q46, an inverter IV2, a delay circuit DL, etc., is inhibited, and a source voltage VCC is lowered to test the lower-limit voltage operation, etc. Consequently, the dynamic RAM performs the automatic starting operation and lower-limit voltage operation testing selectively when powered on. |
