Finding an Analog Multiplexer for Accurate Voltage Measurements

[BillyBobjoe]

Hi

I need to take in a number of analog voltages onto an ADC but the ADC is a single input. I was thinking of putting the voltages through a MUX and then selecting the input desired to go to the output of the MUX and onto the ADC.

Does anyone know of good analog MUX's/Switches that will allow the desired voltage on the input of the MUX to be selected to go to the output.

My voltage measurements need to be accurate so the input voltage on the MUX must also be seen at the output.

Or is there another way i could go about switching through my voltages into the single input ADC.

Thanks

 

[berkeman]

Hi

I need to take in a number of analog voltages onto an ADC but the ADC is a single input. I was thinking of putting the voltages through a MUX and then selecting the input desired to go to the output of the MUX and onto the ADC.

Does anyone know of good analog MUX's/Switches that will allow the desired voltage on the input of the MUX to be selected to go to the output.

My voltage measurements need to be accurate so the input voltage on the MUX must also be seen at the output.

Or is there another way i could go about switching through my voltages into the single input ADC.

Thanks

Does your ADC already have a sample-and-hold circuit? If not, you would use the analog mux as the S/H as well as the mux.

Just google analog mux, and you will get lots of good hits. Linear Technology, Maxim, Analog Devices, National Semiconductor all make them. You will pay more for switches with lower ON resistances, so you need to figure out your S/H circuit, including the capacitor value and how fast you want to sample, and how long you want to hold. That will help you choose the ON resistance and OFF leakage current specs to use in picking the device.