Semiconductor switches are broadly divided into signal switches and load switches designed to turn on and off power supply rails. The following describes signal switches. There are two types of signal switches: those that handle digital signals and those that handle analog signals.
Bus switches were developed to transmit digital signals. In the case of a digital signal, it is necessary to transmit its logic states (including voltage levels) with little or no delay. In contrast, analog switches require signal linearity.
In other words, low capacitance and on-resistance are important for bus switches whereas analog switches require on-resistance that is low and constant over the voltage range in which a signal is transmitted.
Generally, the on-resistance of both p-channel and n-channel MOSFETs for switching applications depends on control voltage as well as the voltage of the signal passing through a switch. To compensate for this voltage dependence, an analog switch is composed of p-channel and n-channel MOSFETs connected in parallel. This makes its on-resistance constant over the operating voltage range, yet at the expense of increased switch capacitance.
In contrast, a bus switch is composed using only a p-channel MOSFET. Although its on-resistance is also dependent on voltage, it is low enough that it does not interfere with the transfer of digital signals.
Therefore, bus switches are ideal for high-speed digital transmission. To transmit an analog signal, use an analog switch with analog electrical characteristics.
The following documents also contain related information:
Tell me about the handling of the unused input terminal of bus switches and analog switches.
What is the difference between level-shifting bus switches and bus buffers?
Is it necessary to add an external pullup resistor between the input or output pins of a dual power level shift bus switch type and the power supply(VCCA or VCCB)?
Product web page