How to find the right Analog Multiplexers AI guide

What the AI looks for in Analog Multiplexers

Signal range versus supply rails

The analog signal must stay between the switch's supply rails (VDD and VSS/VEE). To pass negative signals, choose a part with a separate negative supply pin and power it. Signals outside the rails forward-bias the internal protection diodes, which corrupts the signal and can damage the chip.

Channel configuration

Match the topology to the job: 8:1 single (4051-type), dual 4:1 (4052-type), triple 2:1 (4053-type), or 16:1 (4067-type). The number of select lines and common outputs is fixed by the topology. Picking the wrong one wastes GPIO pins or leaves you short of channels.

On-resistance and flatness

Classic 4000/74HC parts have on-resistance in the hundreds of ohms. Use a low-Ron precision part when the mux drives a low-impedance load or carries current. On-resistance forms a voltage divider with the load and varies with signal level, which causes gain error and distortion.

Charge injection and leakage

For sample-and-hold, high-impedance sensors or ADC front ends, compare charge injection and off-leakage specs, not only Ron. These set the error you see when switching between high-impedance sources, and they often matter more than Ron.

Logic-level compatibility

Check that the select and enable input thresholds work at your microcontroller's logic voltage (for example, 3.3 V logic driving a mux powered at 5 V or more). Some older parts reference logic thresholds to their analog supply and won't switch reliably from low-voltage logic.

Break-before-make and package

Need break-before-make if two sources must never be shorted together during switching. Choose DIP or a breakout board for breadboards, SOIC/TSSOP for PCBs. Momentary shorts between channels can upset sources, and the wrong package simply won't fit.