Vdd

5.5V

1.8V

Switch

Driver

0V

-5.5V

Vdd

5.5V

0V

-5.5V

Figure 7-1. Beyond the Supply Signal Support

7.3.2 Bidirectional Operation

The TMUX28xx conducts equally well from source (Sx) to drain (Dx) or from drain (Dx) to source (Sx). Each

channel has very similar characteristics in both directions and supports both analog and digital signals.

7.3.3 Power-Off Protection

The TMUX28xx has powered-off protection up to ±5.5V on the switch path. This keeps the switch in a high

impedance mode and isolates the source (Sx) and drain (Dx) pins when the supply is removed (Vdd = 0V).

Powered-off protection minimizes system complexity by removing the need for power supply sequencing on

the signal path. The device performance remains within the leakage performance mentioned in the Electrical

Specifications. For more information on powered-off protection, refer to Eliminate Power Sequencing with

Powered-off Protection Signal Switches.

5.5V

0V

Switch

Driver

0V

-5.5V

5.5V

0V

-5.5V

Figure 7-2. Beyond the Supply Power-Off Protection

7.3.4 1.2V and 1.8V Logic Compatible Inputs

The TMUX28xx has 1.2V logic compatibility with a supply of 1.8V and a 1.8V logic compatibility with a 5V supply

(VDD). Having lower logic level inputs allows the device to interface with processors that have lower logic I/O rails

and eliminates the need for an external translator, which saves both space and bill of material (BOM) cost. For

more information on 1.8V logic implementations, refer to Simplifying Design with 1.8V logic Muxes and Switches

7.3.5 Integrated Pull-Down Resistor on Logic Pins

The TMUX28xx has internal weak pull-down resistors to GND so the logic pins are not left floating. This feature

integrates up to two external components and reduces system size and cost.

The value of this pull-down resistor is approximately 6MΩ.

7.3.6 Fail-Safe Logic

The TMUX28xx supports Fail-Safe Logic on the control input pin (SEL) allowing for operation up to 5.5V,

regardless of the state of the supply pin. This feature allows voltages on the control pin to be applied before

the supply pin, protecting the device from potential damage. Fail-Safe Logic minimizes system complexity by

removing the need for power supply sequencing on the logic control pins. For example, the Fail-Safe Logic

feature allows the logic input pin of the TMUX28xx to be ramped to 5.5V while VDD = 0V. The logic control input

is protected against positive faults of up to 5.5V in powered-off condition, but does not offer protection against

negative overvoltage conditions.

TMUX2821, TMUX2819

SCDS488 – DECEMBER 2025

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