Relationship between CD4051's switching voltage and power supply voltage VCC

bigbat

Relationship between CD4051's switching voltage and power supply voltage VCC [Copy link]

Is there any relationship between the input voltage and power supply voltage of the CD4051 analog switch commonly used in circuits? As shown in the following figure: VCC = 5V, the input voltage in the analog switch may be 0-10V. Can the CD4051 work normally?

maychang

"As shown in the following figure: VCC = 5V, the input voltage in the analog switch may be 0-10V. Can CD4051 work normally?"

cannot.

The input voltage is not allowed to exceed the positive terminal of the power supply, nor is it allowed to fall below the negative terminal of the power supply.

maychang

The analog input terminal cannot exceed the power supply rail, which must be noted in the manual.

maychang

In the figure posted by the OP, the voltages on the VIN1~VIN8 pins and the VINx pin should not be called "switching voltages" because these pins mainly process continuously changing analog quantities.

On the contrary, the voltages of pins 6, 11, 10, and 9 can be called "switching voltages" because these pins input digital quantities, which are either high levels or low levels.

maychang

This post seems to be about the same issue as the one posted by the original poster a few days ago, "Problem with CD4051".

I replied in that thread that "This circuit is not completely inoperable. But it needs considerable improvement", which means that after improving the circuit, analog switches such as CD4051 can still be used to select the resistance range. The internal resistance of the analog switch can be connected in series with the resistance to be measured, but it does not affect the measurement result.

bigbat

Thank you @ maychang , if VDD=12V, and the digital gate circuit is controlled, A, B, C, EN is 5V, can it work? However, the manual says that it can work, but I am not sure.