Dual SP4T multiplexer — 100 Ohm Ron, 150 ns switching
The MAX309CSE+T: On-resistance is 100 Ohm maximum with 1.5 Ohm channel-to-channel matching, ensuring consistent attenuation across all four input channels. Switching is symmetrical at 150 ns for both turn-on and turn-off, suitable for audio routing, data acquisition front-ends, and test equipment signal chains.
Signal integrity — crosstalk and charge injection
Crosstalk is rated at -92 dB at 100 kHz, meaning less than 0.0025% of the signal on one channel couples into an adjacent off-channel. This isolation matters when multiplexing low-level sensor signals or audio paths where bleed-through would corrupt the measurement. Charge injection is 2 pC typical — the amount of charge dumped onto the signal line when the switch turns off. For a 10 kOhm source impedance, this translates to a 20 mV glitch; the downstream sample-and-hold or ADC must settle past this before conversion. Off-channel leakage is 750 pA maximum, and off-capacitance is 26 pF on the drain side. These set the floor for how much the off-channel loads the bus and how fast the signal can settle when switching between channels.
Package and supply integration
Dual-supply mode from ±5 V to ±20 V allows true bipolar signal switching without DC offset. The supply pins require local decoupling per the datasheet recommendation — a 0.1 µF ceramic at each rail close to the package.