In many electronic circuits there is a need to share a specific input (or several inputs) by multiple signal sources. If all sources are to be measured using A/D converters, it is of course possible to use separate ADCs for each input. However, such a solution is expensive, and usually requires a significant increase in the size of the PCB or, if this is not possible, a much denser packaging of the analog part of the project. In most cases, multi-channel multiplexers come in handy, of which 16-bit multiplexers are probably the most common.
Multiplexers - saving I/O lines, PCB space and... money
Multiplexers are one of the most "economic" solutions to the problem of multi-channel projects in all fields of electronics. For example, it is worth mentioning multi-channel measuring systems - there is no better way to effectively use a high-end laboratory module to handle several or more measuring points. This is how the vast majority of so-called data acquisition systems (DAQ), widely used in industry, research and monitoring applications of complex physical processes, work. Multiplexer allows sequential switching of successive measurement inputs to the same analog-to-digital converter or signal conditioning system - it must be ensured that the converter itself is able to operate at the appropriate frequency, necessary for effective sweeping of all channels.
Demultiplexer - reverse conversion
It is also worth mentioning a lot of other applications of analog multiplexers. Nothing stands in the way of the integrated multiplexer - e.g. 74HC4067, which you can find in our offer in the form of SparkFun module with catalogue number BOB-09056 - has a common input (marked as COM or SIG) connected to the output of the DAC. Then changing the configuration of the address inputs will cause setting on a specific selectable output with the number 0..15 the voltage, prevailing on the output of the DAC. After adding separate low-pass filters to all sixteen channels, you can control the voltage in each channel independently - it is enough to sweep all the outputs quickly enough, setting the appropriate voltage at the DAC output each time. If the system works in such a mode, we call it a demultiplexer, as opposed to more frequently used multiplexers. Demultiplexers are particularly useful in microcontrollers, equipped with only one or two DAC channels - it is rare that there are more separate DACs in the structure of a system.
Example applications of multiplexers
Apart from typical laboratory applications, other examples of applications where 16-bit multiplexers are useful are also worth mentioning. They can be successfully used e.g. in extended audio mixers, as input selector for selecting signals to be mixed and further processed. Another interesting application will be mobile robots of the line follower class - it is not known from today on that it is the richly sensed constructions that can cope better with the dynamic travel of the whole route, because the ability to precisely determine the position of the line on the ground allows for more efficient traction control. 16-channel multiplexers will also be used by people designing their own intelligent home controller - it is not difficult to indicate examples of sensors that are worth using in such an installation (e.g. analog temperature sensors LM35, humidity, lighting or liquid level sensors - nothing stands in the way of multiplexing simple sensors with two-state output).