74HC4067 Multiplexer: 7 Signal and Settling Checks
A 74HC4067 routes one of sixteen channels through an analog switch to a common terminal. It does not digitize, amplify or protect the signal for the host. Select the exact manufacturer part and signal-conditioning arrangement before assuming sixteen sensors can share an ADC without measurement changes.
Identify HC versus HCT and manufacturer
The cited Nexperia document covers HC and HCT versions with different control-input thresholds and operating ranges. A similarly named module from another manufacturer may have different limits. Apply the exact fitted part’s recommended conditions, not the broadest number found in a family comparison.
Keep signals within the permitted rails
The selected analog path is bidirectional, but its terminals still have voltage limits referenced to the device supply. It is not an automatic 5 V to 3.3 V level shifter or a way to connect negative signals to an unprotected ADC. Verify both switch and host limits.
Include ON resistance in the circuit
The enabled switch has nonzero resistance that depends on supply, signal level and temperature. This resistance can create voltage error with a load and increases acquisition time with capacitance. Do not replace the channel with an ideal wire when estimating ADC settling or filter behaviour.
Budget for source impedance and leakage
High-impedance sources are more sensitive to leakage, charge sharing and the ADC sample capacitor. Choose buffering or acquisition timing where required. A stable result on a low-resistance potentiometer does not establish equal performance for every resistive sensor or long cable attached later.
Use enable for a defined disconnected state
The enable input is active low: a high level turns all switches off. Four select lines choose the channel when enabled. Disabled does not mean the common node is grounded; it can float or retain charge unless the surrounding circuit defines its state.
Distinguish switching speed from sample readiness
Fast address propagation does not guarantee that the complete sensor and ADC network has settled to the required accuracy. The typical break-before-make feature also does not create a precision simultaneous-sampling system. Determine acquisition behaviour using the full source and load arrangement.
Newest in the store
Start with a low-risk measurement role
Use known low-voltage sources and high-impedance measurement inputs for initial validation. Do not route motors, relay coils, mains or substantial load current through the analog switch. This guide does not establish metrology accuracy or safety isolation for a completed multi-channel instrument.
Frequently asked questions
Does the chip provide sixteen ADCs?
No. It routes signals; the host still needs an ADC and suitable acquisition timing.
Is a disabled common terminal guaranteed to read zero?
No. It is disconnected and may float or retain charge.
Availability and illustration note
No matching Epro product was returned by the catalog search on 21 October 2026 UTC. This learning guide does not assert stock, a selling price or compatibility of an unidentified substitute. The illustration is an original conceptual signal-flow diagram, not a product photograph or complete wiring schematic.
Related Epro reading
For a first bench setup, review breadboard connections and continuity checks and I2C voltage-level translation. These guides do not replace the exact module schematic.
Technical references and limitations
Source: Nexperia 74HC4067/74HCT4067 datasheet. Electrical limits apply to the named part, not automatically to every carrier board. This is a documentation-based learning workflow, not a claim of independent hardware testing, traceable calibration or safety certification.