Hi Rolek, When changing channels, there are two main capacitors that must be charged during the acquisition phase. Please refer to Figure 33 in the datasheet. The first capacitor is the Cmux=13pF, which is the total effective capacitance of the MUX itself. The second capacitor is the actual input sampling capacitor of the ADC converter, Cs=60pF. The advantage of adding a buffer between MUXOUT and ADC-AIN is that one amplifier can drive the ADC, and if the source resistance driving the inputs is low enough, you do not need additional amplifiers driving each of the multiplexor inputs. This is not always the case depending on the sampling rate and resolution of the ADC. Take a look at this application note that discusses this subject in much more detail. http://www.ti.com/lit/an/sbaa308a/sbaa308a.pdf There may be some applications where the impedance of a sensor is very high and a buffer is required. In this case, it may be easier to short the MUXOUT and AINP together, and just use a buffer per each input channel. Again, it depends on your system. The ADS8166 gives you the flexibility to optimize where and how many buffers to use. Regards, Keith N. Precision ADC Applications
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