| 摘要 |
PURPOSE:To sense the decrease in the voltage of a load accurately, by obtaining a constitution wherein a reference voltage itself is not subjected to the effect of a threshold voltage of a metallic oxide semiconductor, and compensating said threshold voltage of the metallic oxide semiconductor. CONSTITUTION:A series circuit of resistors R1 and R2 generates the reference voltage corresponding to the voltage variation in a power source connected to input terminals 1 and 2. At N channel MOS transistor Tr1 outputs a voltage corresponding to the reference voltage and a threshold voltage of an N channel MOS transistor Tr2. Said voltage is applied to the gate of Tr2, and its ON resistance is varied. When the power source voltage is decreased and the voltage generated at the input terminal of the inverter 5 becomes larger than the threshold voltage of the inverter 5 due to the resistance value of Tr2 and a resistor RL, the output is changed from a high level to a low level. In this constitution, the decrease in the power source voltage such as a battery can be accurately sensed. |
