8:1 analog multiplexer in 16-SOIC
The MAX4508CSE+ is an 8-channel single-ended CMOS analog multiplexer from Analog Devices, configured as an 8:1 multiplexer/demultiplexer circuit. It routes one of eight analog inputs to a common output under digital control, with the channel selected by a 3-bit address bus. The tube packaging is the factory-shipping format — 50 or 100 per tube depending on the reel-to-tube conversion at the distributor.
Signal path and switching performance
On-state resistance is 400 Ohm maximum across the full analog signal range. This sets the insertion loss: into a 10 kOhm load the divider ratio is about 96 %, so the signal sees roughly 4 % attenuation from the switch alone. Channel-to-channel matching is 15 Ohm max, keeping the gain error consistent across all eight inputs. Charge injection is 2 pC typical — the amount of charge dumped onto the signal line when the switch turns off. For a 100 pF sampling capacitor this translates to a 20 mV glitch; for higher capacitance loads the voltage step is proportionally smaller. This matters in precision data-acquisition front-ends where the glitch must settle before the ADC conversion starts. Crosstalk between channels is -62 dB at 1 MHz, meaning less than 0.08 % of a 1 MHz signal on one channel couples into an adjacent off-channel. For audio-band or low-frequency sensor signals this is effectively silent; for high-speed multiplexing above 100 kHz the -62 dB floor still gives about 14 bits of isolation. Switching times are 275 ns max turn-on and 200 ns max turn-off. The throughput ceiling for a multiplexed system is set by the slower of the two: 275 ns means the channel can be switched at roughly 3.6 MHz if the downstream circuit settles in time. Off-channel leakage is 500 pA max, negligible for most signal sources. Channel capacitance is 10 pF on the source side and 19 pF on the drain side. The 19 pF at the common output node sums with the next-stage input capacitance and sets the bandwidth roll-off: into a 10 kOhm load the -3 dB point is about 840 kHz.
The dual-supply option lets the analog signal swing below ground, useful for bipolar sensor outputs or AC-coupled signals. The single-supply range covers common industrial rails (12 V, 24 V) and the 9 V minimum allows operation from a standard 9 V battery. Temperature range is commercial grade: 0 °C to 70 °C ambient. This limits the part to indoor, temperature-controlled environments — server rooms, lab equipment, benchtop instruments, and consumer electronics. Not rated for automotive or extended industrial temperature extremes.
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