This slide shows a typical PLC input stage and several multiplexers that are suitable for this signal chain. The ADG509F multiplexer provides fault protection using a series n-channel, p-channel, n-channel MOSFET structure. Both the device and signal source are protected in the event of an over voltage or power loss. The multiplexer can withstand continuous over voltage inputs from –40 V to +55 V. During fault conditions, the multiplexer input or output appears as an open circuit and only a few nanoamperes of leakage current will flow. Also shown is the ADG1408 which has ultra low On-resistance and excellent resistance flatness making it an ideal solution for data acquisition and gain switching applications where low distortion is essential for reliable and predictable circuit performance.