| 摘要 |
<p>PURPOSE:To detect a power source voltage drop with a constitution in which no transistor of high threshold voltage is required, by utilizing a voltage drop caused by plural stages of transistors. CONSTITUTION:Three, for example, transistors 1-3, the drain and the gate of which are connected in common, are connected to a power source 10 with a voltage of VCC in series with a threshold value VH, and the voltage at a node (a) goes to VCC-3VH by the voltage drop through the transistors 1-3. And when the voltage VCC drops more than a prescribed level, an N-type of transistor 5 in an inverter 6 is turned off, and a node (b) goes to H, then the power source voltage drop is detected. By the use of the plural transistors, the power source voltage drop can be detected using an usual transistor, without using the transistor with high threshold voltage, and a switching to a data retention mode can be performed automatically.</p> |
