I'm looking to use the following switch to switch an SPI bus ( CLK <= 2Mhz) between two different devices.
I'm reading the datasheet to see if the the frequency of the signals are going to be ok, and I'm not sure I quite understand the High Frequency Performance section (Pg 9 of the datasheet)
In 50Ω systems, signal response is reasonably flat up to 50MHz (see Typical Operating Characteristics). Above 20MHz, the on-response has several minor peaks that are highly layout dependent. The problem is not turning the switch on, but turning it off. The off-state switch acts like a capacitor and passes higher frequencies with less attenuation. At 10MHz, off-isolation is about -50dB in 50Ω systems, becoming worse (approximately 20dB per decade) as frequency increases. Higher circuit impedances also degrade off-isolation. Adjacent channel attenuation is about 3dB above that of a bare IC socket and is entirely due to capacitive coupling.
What would be considered to be a 50ohm system ? Is this referencing to the trace impedance ? Would SPI communication lines be considered 50ohm ?