Because this device has such a low on-resistance, it can be used in applications with very low output speaker

impedance such as 8Ω or 4Ω systems. In these applications, the current through the switch can increase

drastically, causing self heating.

16.2.2 Smart Drug Delivery Flow Meters

For smart drug delivery applications, a precise measurement of the dosage must be monitored. One very

accurate architecture that is used is differential time of flight (TOF) using transducers. Many liquid flow sensor

systems are higher attenuation compared to gas applications. In these high attenuation scenarios, a higher

excitation voltage is used to significantly increase the signal to noise ratio (SNR). A bidirectional 2:1 multiplexer

is used to switch the transmission and reception signals from the MCU to the transceivers without distortion.

Because the TMUX48xx can support signals beyond the supply, it is an excellent choice for handling this higher

excitation voltage. The TMUX48xx can be used to switch up to -15V to 15V with a supply voltage from 1.8V to

5.5V, with an ultra-low on-resistance to minimize the impact on the signal quality. The supply can also be driven

directly with a GPIO, allowing the user to put the device into ultra-low power mode. In this mode the TMUX48xx

operates with powered-off protection, so any high voltage present on the inputs will not propagate to the outputs.

This allows correct power up cycling and increases system robustness. Additionally, the TMUX48xx features

excellent THD+N performance, so there is minimal impact to the signal quality through the switch.

ADC

DAC

GPIO

MSP430

VDD

SEL

SEL

VDD

Figure 16-4. Smart Drug Delivery Flow Meters

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TMUX4821, TMUX4819

SCDS487A – OCTOBER 2025 – REVISED DECEMBER 2025

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