RF Output

TMUX1237

SEL

1.8 V

DAC

0 V

5 V

RF Input

20

TMUX1237

SCDS424A – DECEMBER 2019 – REVISED MARCH 2020

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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 (1.08 V to 5.5 V). These

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

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

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

features of the TMUX12xx, a family of general purpose multiplexers and switches, reduce system complexity,

board size, and overall system cost.

9.2 Typical Application

9.2.1 Input Control for Power Amplifier

One application of the TMUX1237 is for input control of a power amplifier. Utilizing a switch allows a system to

control when the DAC is connected to the power amplifier, and can stop biasing the power amplifier by switching

the gate to GND. Figure 17 shows the TMUX1237 configured for control of the power amplifier. The no overshoot

when switching between inputs feature of the TMUX1237 is beneficial in applications such as this where the

output is being switched across the full voltage range, and any overshoot on the output is undesired.

Figure 17. Input Control of Power Amplifier

9.2.1.1 Design Requirements

This design example uses the parameters listed in Table 3.

Table 2. Design Parameters

PARAMETERS

VALUES

Supply (VDD)

5 V

Switch I/O signal range

0 V to VDD (Rail to Rail)

Control logic thresholds (SEL)

1.8 V compatible (up to 5.5 V)

Signal overshoot

0 V