| 摘要 |
PURPOSE:To make it possible to reset power ON even if a power supply voltage is higher or lower than a prescribed value and to initialize a logical circuit precisely by forming two comparators for comparing the power supply voltage with upper and lower limit values respectively. CONSTITUTION:Power ON is reset instantaneously when the power supply voltage Vs exceeds an upper limit value Vref1 by an upper limit comparator 10 in a power ON reset circuit and then drops again less than the Vref1 and also reset instantaneously when the power supply voltage Vs drops lower than a lower limit value Vref2 by a lower comparator 11 and then exceeds the Vref2 again. An AND gate 12 inputting the outputs of the upper and lower limit comparators 10, 11 finds out the AND of both the outputs, and inputs its output signal to the succeeding rise differentiation circuit 13. At the rise of the input signal from the gate 12, the circuit 13 output a reset signal RS, so that the power supply voltage Vs can be reset even if the Vs is higher or lower than the prescribed value. |
