Single SPST-NO switch in a SOT-23-5 — what the ratings tell you
The MAX4516EUK+T is a single-pole single-throw normally-open analog switch. The 20 Ohm on-resistance sets the voltage drop across the switch for a given load current.
Charge injection and leakage — the quiet side of the switch
Charge injection is rated at 10 pC. That is the amount of charge dumped onto the signal line when the switch turns off — relevant if you are driving a sample-and-hold capacitor or a high-impedance ADC input. 10 pC into a 10 nF hold cap gives a 1 mV glitch; into a 100 pF cap it is 100 mV. Off-state leakage is 1 nA maximum, which is low enough that it will not shift a 10 kΩ source impedance by more than 10 µV. Channel capacitance is 9 pF on both sides — that plus the source impedance sets the bandwidth, roughly 1/(2π × R_source × 9 pF).