System Inputs &

Sensors

LDO #1

D

S1

S2

S3

S4

S5

S6

S7

S8

Integrated

12-bit ADC

A0

A1

A2

EN

MCU

LDO #2

LM20

Analog Temp.

Sensor

LM20

Analog Temp.

Sensor

GND

VDD

VDD

VDD

VI/O

1.8V Logic

I/O

LM20

Analog Temp.

Sensor

LDO #3

RAM

FLASH

Port I/O

TIMERS

22

TMUX1208, TMUX1209

SCDS389C – AUGUST 2018 – REVISED DECEMBER 2018

www.ti.com

Product Folder Links: TMUX1208 TMUX1209

Submit Documentation Feedback

Copyright © 2018, Texas Instruments Incorporated

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. Customers should

validate and test their design implementation to confirm system functionality.

9.1 Application Information

The TMUX12xx family offers good system performance across a wide operating supply (1.08V to 5.5V). These

devices include 1.8V logic compatible control input pins that enable operation in systems with 1.8V I/O rails.

Additionally, the control input pins support Fail-Safe Logic which allows for operation up to 5.5V, regardless of

the state of the supply pin. This protection stops the logic pins from back-powering the supply rail. These

features make the TMUX12xx a family of general purpose multiplexers and switches that can reduce system

complexity, board size, and overall system cost.

9.2 Typical Application

One useful application to take advantage of the TMUX1208 features is multiplexing various signals into an ADC

that is integrated into a MCU. Utilizing an integrated ADC in a MCU allows a system to minimize cost with a

potential tradeoff of system performance when compared to an external ADC. The multiplexer allows for multiple

inputs/sensors to be monitored with a single ADC pin of the device, which is critical in systems with limited I/O.

The TMUX1209 is suitable for similar design example using differential signals, or as two 4:1 multiplexers.

Figure 18. Multiplexing Signals to Integrated ADC

9.3 Design Requirements

For this design example, use the parameters listed in Table 3.

Table 3. Design Parameters

PARAMETERS

VALUES

Supply (VDD)

5.0 V

I/O signal range

0 V to VDD (Rail to Rail)

Control logic thresholds

1.8 V compatible