DG421DJ - Low-Power Latched SPST CMOS Switch | Maxim

Multiplexed Sensor Acquisition

The DG421DJ can route multiple sensor lines into a shared analog front end when its dual SPST topology and latched control are suitable for the system architecture. Its guaranteed on-resistance matching of 3 ohms maximum helps reduce channel-to-channel gain errors, while the 4-ohm maximum flatness limit helps maintain more uniform signal behavior over the operating range. A typical implementation would connect the two switch channels between selected sensors and a measurement amplifier or ADC input. Before finalizing the design, verify the manufacturer's input-voltage, current, bandwidth, capacitance, and leakage limits because those values are not present in the supplied search excerpts.

Programmable Test Fixtures

The DG421DJ is applicable to programmable test fixtures that require repeatable signal-path selection and a retained routing state. The latch feature can reduce the need to hold a control command continuously while the fixture remains configured. For dual-channel measurements, the 3-ohm maximum on-resistance matching provides a defined limit for path-to-path variation, and the 4-ohm maximum flatness provides a controlled signal-range specification. The DIP-16 through-hole package is useful where sockets, connectorized fixtures, or manual rework are preferred. Engineers should still check the complete datasheet for logic levels, switching time, signal bandwidth, and allowable analog voltage before using it in automated production test.

Sample-and-Hold Signal Routing

The DG421DJ can support sample-and-hold architectures where two independently selectable SPST paths connect a source to a sampling node or auxiliary instrumentation. Its 20-ohm typical on resistance adds a defined series-resistance term that must be included in source impedance and settling-time analysis. The matching and flatness guarantees support more consistent behavior between the two selected paths. A practical design would use the latch to preserve the selected connection during acquisition and would route the hold capacitor and amplifier for minimum leakage and noise pickup. Because the verified data omits charge injection, off leakage, bandwidth, and power-supply limits, those characteristics require direct review of the full Maxim Integrated datasheet.

Industrial Control Signal Routing

The DG421DJ fits industrial signal-routing modules that need two selectable SPST analog paths, electronic control, and DIP-16 through-hole construction. Its industrial temperature grade supports use in industrial equipment, although the exact numeric operating-temperature limits are not included in the supplied excerpts. The dual channels can route control or feedback signals, and the latched state can simplify system sequencing. Because the verified data confirms a 20-ohm typical on resistance rather than a complete minimum and maximum specification, engineers should evaluate source impedance, injected error, available drive current, and switching transients under worst-case conditions.

Data Acquisition Switching

The DG421DJ may be used in data-acquisition boards to connect selected analog inputs to downstream measurement circuitry. Two SPST channels and guaranteed 3-ohm maximum matching can support paired or differential routing functions, while 4-ohm maximum flatness limits resistance variation across the stated signal range. The bidirectional conduction behavior allows the switch to be used for signal paths where direction changes with the acquisition source. A practical implementation should minimize PCB leakage around high-impedance nodes and place the switch where its capacitance will not compromise acquisition bandwidth. The complete datasheet is required to confirm switch-off isolation, charge injection, operating voltage, and logic compatibility.

Low-Power Control Module

The DG421DJ is appropriate for low-power control modules that need a compact, electronically controlled analog-routing function with a latched state. Its designation as an improved low-power CMOS analog switch supports power-conscious signal-path designs, while the DIP-16 package offers through-hole accessibility for industrial and educational equipment. The latch can maintain a chosen connection without requiring a continuously toggled control waveform. Design validation should include a detailed power-consumption estimate based on the actual supply voltage and control sequence, plus confirmation of logic thresholds, quiescent current, and switching behavior because the supplied source material does not provide those numerical limits.