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Voltage measurement issue from ADG658

Question asked by sumit.ranjan on Sep 14, 2017

Hi Team,


I am using two Multiplexer having part number ADG658 (8:1 MUX) and ADG732BSU (32:1 MUX).  Power supply for both MUX i am providing 2.8V and we have to measure some voltage which is higher than 2.8V so using voltage divider to bring to keep input voltage under 2.8V for MUX Input line.

But when i am trying to measure any input line then voltage is getting dip when that input line is selected by selection line.

For e.g- To measure 5V we have used voltage divider and scaled down it for 2.5V and trying to measure the 2.5V. Until we are not selecting the input line we are getting 2.5V at input of MUX but once we are selecting the input line by selection line then that 2.5V is coming down to 0.4V, I don't know what is the exact issue. This issue is happening on all selection line. Please clarify this what is happening and how can we avoid this?


Please refer attached schematic for the reference.