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Advantages and Disadvantages of Analogue Multiplexer vs a ADC chip. For having more analogue inputs on micro-controller. Thx

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  • \$\begingroup\$ You need to expand this question like nobody's business if you expect anyone to understand your question to give you reasonable answer. \$\endgroup\$ – horta Nov 1 '15 at 1:04
  • \$\begingroup\$ The analog mux needs to be driven ,means another chip in your chipcount but if it has some special advantage then it could still be valid .The microprocessor design people I interface for always get a chip with more inputs these days .I guess the ext mux of yesteryear is now built in . \$\endgroup\$ – Autistic Nov 1 '15 at 1:20
  • \$\begingroup\$ If you need an analog output the ADC won't do you much good. \$\endgroup\$ – Brian Drummond Nov 1 '15 at 11:40
  • \$\begingroup\$ A multi input ADC might very well have its own multiplexer. \$\endgroup\$ – Scott Seidman Nov 1 '15 at 14:12
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Sometimes you really need to simultaneously sample several inputs at the same time and a separate ADC for each channel is typically used. For example, the TI ADS1274/1278 has 4 or 8 channels of decent ADC.

If your ADC (on chip or otherwise) is fast enough to sample all the channels in turn then you can perhaps save money and power by time-sharing it between the channels.

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Speed is going to be your limiting factor if using a Multiplexer. Multi input ADCs and uCs have only a couple actual AtoD converter and an internal multiplexer to feed them. The designers of these systems have taken care of all the timing constraints of switching channels and sampling.

If your using your own Multiplexer then you will have to take care of the timing. If speed is not a concern then a then either solution is fine. If speed is a concern then the multi input ADC is your only choice.

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