Abstract

Designs where various sensors are used to monitor different subsystems, tend to be complex due to the numerous amounts of signal paths. A common approach to reduce size and simplify the system is to use an analog multiplexer (mux) to route signals from different sensors into a single ADC. However, due to the break-before-make feature of most muxes, when switching between different channels the drain floats for a short period of time, causing the output voltage signal to slightly drop. Once the switch channel is connected to the new source the signal begins to settle. If the ADC samples before the signal can recover this can lead to an error. Furthermore, this implementation usually includes passive components, such as resistors and capacitors, on the input of the mux which can increase that delay and as a result can increase the ADC error count. For this type of application accurate sensor performance can be very critical. Reducing the input RC caused by the additional components on the input can minimize this delay and settling time: allowing the system to measure these sensors more frequently. Another option is to implement a multiplexer with improved functionality reducing settling time and improving system performance. The TMUX1308A-Q1 is designed to provide such a design.