I only need to know how work muxout pins!?!!...

what output of multiplexer? of each channel? of channel selected? same of DO pin?


Hallo Christian,

mayby I can enlighten some points:

Most multichannel ADCs do only contain ONE actual analog to digital converter. In order to achieve conversion for let's say 8 channels (inputs) you need something, that selects only one of these 8 inputs at at time. Only this selected input is fed to the actual analog to digital converter during conversion. This selector is called 'multiplexer' or 'input multiplexer'.

ADCs are often used in applications, where low noise performance is real essential. And people who do not need a multiplexer at input, because they only need a one channel ADC, they can minimize noise, by omitting this mulitplexer. If they feed their signal directly to inputs of "the one analog to digital converter", they can improve noise a bit.

There are also other situations, where it's imaginable to omit this input multiplexer or to have same additional circuitry inserted between input multiplexer and "the one analog to digital converter", think of sophisticated lowpass filtering, for instance. So, people of National Semiconductors have provided the possibility to give direct access to the input of "the one analog to digital converter".

But how to manage this option?
Quite simple by feeding the connection between multiplexer and "the one analog to digital converter" to sperate pins, as it is done with your ADC12130. Not all manufacturers of multichannel ADCs do feed this connection point between multiplexer and "the one analog to digital converter" to separate pins, because number of pins of chip increases, of course. Most manufacturers keep these both parts permanently connected and do not feed the according connection point to seperate chip pins.

In most cases, it's not needed to have direct access to these pins and it's enough just simply to connect multiplexer output to input of "the one analog to digital converter" and not taking any care about this connection in the future.

That's the whole mistery about MUXOUT1, MUXOUT2, A/DIN1 and A/DIN2 pins. Connect them together as recommended in datasheet and relax...

Kai