The 74HC4067 is a 16-channel analog multiplexer/demultiplexer integrated circuit. It allows a microcontroller or other digital circuitry to select one of its 16 channels and connect it to a single common channel. This enables efficient routing of analog signals, such as sensors or audio inputs, to a single input pin on a microcontroller, conserving the number of required input pins. By using digital control signals, it facilitates rapid switching between different input channels, making it ideal for applications requiring monitoring or processing multiple analog signals with limited pins and space, such as in data acquisition systems or sensor arrays.
Using the 74HC4067 is very simple it only requires a single de-couple capacitor and a resistor to prevent the output enable line (E) from floating. It's good practice to have a de-couple capacitor between Vcc pin and ground on every power pin on an IC. Typically this can be anything between 0.1uF down to 0.01uF. I normally use 0.1uF on my designs, but I'm not generally working with high speed signals > 10MHz
To use the 74HC4067 we need just to connect Vcc and Gnd. The HC version support Vcc from 2V to 6V but the HCT version only supports 4.5V to 5.5V. The COMMON pin is connected to the analog pin on the microcontroller. In the example below this is A0. The active analog pin on the 74HC4067 is chosen by the digital signal pins S0, S1, S2 and S3. The active pin is set by the binary value set on the input pins. The logic truth table below shows how the channel selection works.
The circuit shows the weak pull-down resistor on the output enable pin (E). This will cause the output to always be enabled unless a voltage is applied to the enable pin.
74HC4067
The 74HC4067 16 Channel Analog Multiplexer datasheet.
Note: There are other manufacturers of these components, I have just included these datasheets for your reference.
