Dual SPDT switch with 4 Ohm on-resistance
The MAX4636EUB+ is a dual SPDT (2:1 multiplexer/demultiplexer) analog switch from Analog Devices, housed in a 10-pin uMAX/uSOP package. Switching is fast: 14 ns typical turn-on, 6 ns turn-off. The 2 pC charge injection means the switch dumps a small packet of charge into the signal path when it toggles — at 2 pC into a 10 pF sampling cap that's a 200 mV glitch, so a downstream sample-and-hold needs to settle before the ADC conversion starts.
Signal integrity specs for the BOM
Off-isolation is characterised by -67 dB crosstalk at 1 MHz — the signal leaking from one channel to the other at that frequency is about 0.045% of the input. For a 10-bit system with 0.1% LSB, that's below the noise floor; for a 16-bit system it's marginal and the layout needs to keep the two channel traces separated. Leakage current is 100 pA max off-state, and channel capacitance is 9 pF. The 100 pA leakage into a 1 MOhm load creates a 100 µV offset — negligible for most signal chains. The 9 pF capacitance loads the source when the switch is off, which matters for high-impedance sources above 100 kHz where the capacitive divider starts to attenuate the signal.
The Tube shipping format means the parts are delivered in a stick, not tape-and-reel — factor in the handling for pick-and-place if the line is set up for reels only.