One key application of the
TMUX7234 is in the ultrasonic water flow measurement system. Ultrasonic flow meters use time of flight (ToF) of an ultrasonic wave and its dependency and behavior in the medium using two transducer pairs for upstream and downstream paths. The signal waveforms are transmitted between two adjacent transducers. One transducer transmits an upstream path signal and the other transducer receives a downstream signal path. The flight time for the signal can be calculated using the known velocity of sound and length between the transducers. The upstream and downstream waveforms are processed on the main MCU to obtain the volume.
Figure 8-1 shows a circuit example utilizing the MSP430FR66047 MCU, high voltage low distortion operational amplifiers (THS3091), along with
TMUX7234, 2:1, 4 channel precision switches. The
TMUX7234 is used to select the Rx and Tx path of the transducer. The
TMUX7234 offers low on-state resistance, flat capacitance performance, and low propagation delay which leads to very low signal distortion. The break-before-make feature allows transferring of a signal from one port to another, without shorting the inputs together. This device also offers low charge injection which makes this device suitable for high precision data acquisition systems.