| 摘要 |
PURPOSE:To provide immunity against external noise and to prevent malfunction against internal noise by providing a means of quick charging to a 2nd capacitor externally mounted and connecting to an output of a 2nd charge discharge changeover circuit. CONSTITUTION:An output of a comparator 19 through an inverter 30 and an output of a comparator 28 are NANDed, and the moment when the output of the comparator 28 is inverted, an output of a NAND gate 29 goes to a low level to activate a PNP transistor(TR) 25. Thus, an externally mounted capacitor 24 is charged quickly before a switching noise of an NPN TR 23 at an output stage through a resistor 27 and external noise inputted from a terminal 36 are superimposed on a reference voltage. Thus, the output of the comparator 28 crossing repetitively a threshold potential is prevented, further, malfunction of the comparator 28 is prevented and the effect on the function preventing malfunction in chattering is improved. |
