| 摘要 |
<p>PURPOSE:To output a reset pulse after a power supply voltage rises up to a prescribed value even when the time constant of an integrating circuit is smaller than the time constant of a power source circuit by providing a P channel MOS transistor brought to diode connection between a power source terminal and a resistance to constitute the integrating circuit. CONSTITUTION:Between a power source terminal 5 and a resistance 1, a P channel MOS transistor 3 brought to diode connection is provided. Therefore, after the power source is turned on, a time until a supply voltage VDD rises up to a threshold voltage Vf of the P channel MOS transistor 3 is delayed and thereafter, a capacitor 2 is charged. In such a way, there exists a delay of a time until the supply voltage VDD rises up to the threshold voltage Vf of the P channel MOS transistor 3. Therefore, even when the time constant of the integrating circuit is smaller than the timer constant of the power source circuit, the reset pulse is surely outputted after the power supply voltage rises up to the prescribed value.</p> |
