8 Detailed Description

8.1 Overview

The TMUX722x is a 1:1, 2-channel switch. Each input is turned on or turned off based on the state of the select

line and enable pin.

8.2 Functional Block Diagram

Figure 8-1 shows the functional block diagram of the TMUX722x.

S1

S2

D1

D2

VDD

VSS

SW

SW

SEL1

SEL2

TMUX7221

(SELx = Logic 1)

S1

S2

D1

D2

VDD

VSS

SW

SW

SEL1

SEL2

TMUX7222

(SELx = Logic 1)

Figure 8-1. TMUX722x Functional Block Diagram

8.3 Feature Description

8.3.1 Bidirectional Operation

The TMUX722x conducts equally well from source (Sx) to drain (D) or from drain (D) to source (Sx). Each

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

8.3.2 Rail-to-Rail Operation

The valid signal path input and output voltage for TMUX722x ranges from VSS to VDD.

8.3.3 1.8 V Logic Compatible Inputs

The TMUX722x has 1.8 V logic compatible control for all logic control inputs. 1.8 V 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 BOM cost. For more information on 1.8 V logic implementations, refer to

Simplifying Design with 1.8 V logic Muxes and Switches.

8.3.4 Integrated Pull-Down Resistor on Logic Pins

The TMUX722x have internal weak pull-down resistors to GND to ensure the logic pins are not left floating. The

value of this pull-down resistor is approximately 4 MΩ, but is clamped to about 1 µA at higher voltages. This

feature integrates up to four external components and reduces system size and cost.

8.3.5 Fail-Safe Logic

The TMUX722x supports Fail-Safe Logic on the control input pins (EN, SEL) allowing for operation up to 44

V above ground, regardless of the state of the supply pins. This feature allows voltages on the control pins

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 pins of the TMUX722x to be ramped to +44 V while VDD and

VSS = 0 V. The logic control inputs are protected against positive faults of up to +44 V in powered-off condition,

but do not offer protection against negative overvoltage conditions.

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TMUX7221, TMUX7222

SCDS444 – FEBRUARY 2023

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