TMUX7309F datasheet(26/40 Pages) TI

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8.4.2 Fault Mode

The TMUX7308F and TMUX7309F enter into the Fault mode when any of the input signals on the source

(Sx) pins exceed VDD or VSS by a threshold voltage VT. Under the overvoltage condition, the switch input

experiencing the fault automatically turns OFF regardless of the digital logic status, and the source pin becomes

high impedance with a negligible amount of leakage current flowing through the switch. When the fault channel

is selected by the digital logic control, the drain pin (D or Dx) is pulled to the supply that was exceeded through a

40 kΩ internal resistor.

The overvoltage protection is provided only for the source (Sx) input pins. The drain (D or Dx) pin, if used as a

signal input, must stay in between VDD and VSS at all times since no overvoltage protection is implemented on

the drain pin.

9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The TMUX7308F and TMUX7309F are part of the fault protected switches and multiplexers family of devices.

The abilty to protect downstream components from overvoltage events up to ±60 V makes these switches and

multiplexers suitable for harsh environments.

9.2 Typical Application

In analog input programmable logic controllers (PLC) a multiplexer is often used to switch multiple sensors

to a single ADC. By using a multiplexer, the number of components in the system can be reduced to save

system cost and size. In a PLC module a ±10 V input signal range is common for interfacing with external field

transmitters and sensors; however, there are a number of fault cases that may occur that can be damaging

to many of the integrated circuits. Such fault conditions may include, but are not limited to, human error from

wiring connections incorrectly, component failure or wire shorts, electromagnetic interference (EMI) or transient

disturbances, and so forth.

TMUX7308F

SCDS403A – FEBRUARY 2021 – REVISED OCTOBER 2021

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TMUX7309F Datasheet(PDF) 26 Page - Texas Instruments