The MAX4661CAE+ is a quad single-pole single-throw normally-closed (SPST-NC) analog switch from Maxim Integrated. Each of the four independent switches connects a common terminal to a normally-closed output when the control logic is low. The part is built for precision signal routing in automated test equipment, data-acquisition systems, and industrial control boards where low on-resistance preserves signal amplitude and reduces self-heating. On-resistance is a maximum 2.5 ohms across the rated supply range, with channel-to-channel matching held to 100 milliohms. That matching matters when you are switching multiple channels in a gain-setting or multiplexer application — the offset between channels stays tight enough to avoid gain errors in the downstream ADC. Single-supply operation from 4.5 V to 36 V, or dual supplies from ±4.5 V to ±20 V.
Switching speed and signal integrity
Turn-on time is 275 ns max, turn-off 175 ns max. That is fast enough for relay-replacement in low-frequency switching, audio routing, or sample-and-hold front ends, but not for high-speed digital multiplexing above a few megahertz. Crosstalk is rated at -59 dB at 1 MHz — adequate for separating channels in a multi-channel data-acquisition system without bleeding signal between paths. Charge injection is 300 pC typical. Off-leakage current is 500 pA max, and channel capacitance is 55 pF per side. The low leakage keeps the switch from loading precision analog nodes when off; the capacitance matters for settling time in switched-capacitor filters or when driving long cables.
Housed in a 16-pin SSOP (0.209-inch body width, 5.30 mm), surface-mount only. Tube shipment is the listed packaging form — not tape-and-reel, so plan for pick-and-place if you are running high-volume assembly; you will need to transfer to tape or hand-place.