| 摘要 |
PURPOSE:To eliminate sufficiently noise by providing an analog switch connecting or disconnecting a time constant circuit element so as to change the time constant of an input filter. CONSTITUTION:When noise is not sufficiently eliminated while a signal at an output terminal OUT is supervised, ''1'' is written in a register REG1 by a control signal from a processor or the like, a driver DR1 turns on the analog switch S1 so as to change the time constant of the input filter from R.C1 to R.(C1+ C2), and when ''1'' is written in a register REG2 further, a driver DR2 turns on an analog switch S2 and the time constant is changed to R.(C1+C2+C3). Moreover, the time constant is changed depending whether a resistor R2 is connected in parallel with the resistor R1 or not by means of an analog switch S. |
