TMUX1111 Precision Switch: 7 Checks for Active-Low Four-Channel Control
TMUX1111 Precision Switch: 7 Checks for Active-Low Four-Channel Control
Plan TMUX1111 four-channel switching with active-low controls, bounded signals, independent states, leakage and settling checks. This is a documentation-based planning guide, not a report of independent hands-on testing.
1. Recognize four independent SPST paths
TMUX1111 provides four single-pole, single-throw signal paths rather than one four-to-one analog multiplexer. Each channel has its own source, drain and control. Draw the complete connections before deciding which combinations may be enabled together. If external wiring joins different sources, simultaneous conduction can create a conflict. Independent switches do not provide automatic arbitration, an address decoder or a guaranteed safe selection sequence between externally interconnected channels. That sequencing belongs in the system design. Manufacturer documentation.
2. Correct the active-low control assumption
The TMUX1111 truth table states that a zero on a channel select input turns that channel on and a one turns it off. This differs from active-high relatives. The normally closed description is a powered logic-state convention, not a claim of relay-like conduction without a supply. Set controller reset levels and any pull resistors accordingly. Test each select input independently using bounded sources before trusting a library whose default polarity may describe a different device. Manufacturer documentation.
3. Keep analog and control voltage rules separate
The recommended supply spans 1.08 V to 5.5 V and the analog path supports signals between ground and VDD. Fail-safe logic concerns the digital controls and is not a blanket powered-off protection guarantee for source or drain pins. Review the analog absolute limits, recommended range and supply sequencing separately from the control-input tolerance. A sensor that remains powered while the switch supply is absent may require an interface that this feature description does not provide. Manufacturer documentation.
4. Evaluate on-resistance under real loading
The low on-resistance headline is characterized under specified signal, supply and temperature conditions. Use appropriate limits when calculating attenuation into a resistive load or settling into a sampling capacitor. Include source impedance, wiring and the receiving input network. A near-perfect DC reading with a high-impedance meter does not establish that a fast ADC acquisition interval is adequate. Check whether resistance variation across the waveform introduces a relevant gain or distortion contribution. Manufacturer documentation.
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5. Budget leakage for both open and closed states
A small leakage current can create a meaningful voltage error with a high-impedance sensor or long hold interval. Compare on-state and off-state leakage at the intended temperature and supply, not just the room-temperature typical headline. For a resistive source, leakage multiplied by source resistance is a useful first error estimate. PCB contamination, connectors and instrument input current also belong in the budget. An open channel is not an ideal infinite-resistance boundary or safety isolation. Manufacturer documentation.
6. Separate charge injection from settled measurement
Select transitions can inject charge or couple a disturbance into a sensitive node. Estimate the initial voltage step from charge divided by capacitance where useful, then evaluate the actual network transient. Choose a justified delay before accepting a measurement after switching. Do not borrow a break-before-make assumption from a differently arranged family member to control four independent SPST paths. If the application requires dead time between channels, impose and verify that sequence explicitly. Manufacturer documentation.
7. Validate the control matrix and power sequence
Exercise all single-channel states, all-off and any simultaneous-on combinations that the application actually uses. Repeat with the real receiver and filter attached, then test controller reset and supply transitions while respecting analog limits. Record select polarity, source impedance, supply, temperature and sampling delay with the results. Look for off-state feedthrough as well as static leakage. This creates a defensible channel-state record without claiming that an untested board achieves the manufacturer headline precision. Manufacturer documentation.
Related reading: TMUX1121 Analog Switch: 7 Checks for Independent Channels and Leakage.
Catalog note: The exact-part search did not return a matching Epro listing during preparation. Check the current catalog; this guide makes no price, availability or included-accessory claim.