| 摘要 |
PURPOSE:To prevent the latch-up by connecting the protective diode to the input of the amplifier and at the same time connecting the resistor in series to each input and output of the CMOS analog switch. CONSTITUTION:The resistors R1 and R2 are connected in series to the input terminal each of the CMOS analog switch A2 which performs the switching of transmission for the analog input signal transmitted from the input terminal IN to the output terminal OUT via the signal supplied from the control terminal C. The resistance value of these resistors is selected so that the current flowing to the resistors R1 and R2 may be <=10mA, and also selected to the value less than 10<2> times as much as the onresistance value of the CMOS analog switch beeing on. The input-side amplifier A1 is provided between the input-side resistor R1 and the input terminal. In addition, the diode D1 which works when the input overvoltage signal is larger than the power source voltage V1 is provided, along with the diode D2 which works when the input overvoltage signal is smaller than the power source voltage V2 respectively. |
