Switch topology and signal path
The MAX4544CUA+ is a single-pole double-throw (SPDT) analog switch from Analog Devices, configured as a 2:1 multiplexer/demultiplexer in a single circuit. The 60 Ohm max on-resistance sets the insertion loss floor for the signal path — at DC this is a simple voltage divider with the load impedance, but at higher frequencies the 8 pF channel capacitance (CS(off), CD(off)) starts to dominate the off-isolation roll-off. Switching times are 100 ns max for turn-on and 75 ns max for turn-off, which means the part can handle audio-rate multiplexing and low-speed data switching without introducing timing skew between channels. The 800 mOhm channel-to-channel on-resistance matching keeps the gain error consistent when switching between two signal sources of the same impedance.
Supply flexibility and leakage budget
The 100 pA max off-leakage current (IS(off)) means the switch does not load the signal source when the channel is deselected; in a high-impedance sensor front-end this leakage is negligible compared to the bias current of a typical CMOS op-amp. Charge injection is rated at 1 pC typical. When the switch transitions from on to off, this charge dumps onto the load capacitance — for a 10 pF sample-and-hold cap the resulting voltage step is 100 mV, which may matter in precision analog paths.
Crosstalk and signal integrity at 1 MHz
Crosstalk is specified at -90 dB at 1 MHz. This figure tells you how much of the signal on one channel leaks into the deselected channel — at -90 dB the leakage is about 31.6 µV for a 1 V signal, which is below the noise floor of a 16-bit ADC at full scale. The 8-TSSOP/8-MSOP package (3.00 mm width) keeps the parasitic coupling between pins low; the 0.118-inch body is standard for this pin count.