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 TMUX11xx family offers ultra-low input and output leakage currents and low charge injection. These devices

operate up to 5.5V, and offer true rail-to-rail input and output of both analog and digital signals. The TMUX110x

have a low on-capacitance which allows faster settling time when multiplexing inputs in the time domain. These

features make the TMUX11xx devices a family of precision, high-performance switches and multiplexers for

low-voltage applications.

9.2 Typical Application - Sample-and-Hold Circuit

One useful application to take advantage of the TMUX1101 and TMUX1102's performance is the sample-and-

hold circuit. A sample-and-hold circuit can be useful for an analog to digital converter (ADC) to sample a varying

input voltage with improved reliability and stability. It can also be used to store the output samples from a single

digital-to-analog converter (DAC) in a multi-output application. A simple sample-and-hold circuit can be realized

using an analog switch such as the TMUX1101, and TMUX1102 analog switches. Figure 9-1 shows a single

channel sample-and hold circuit using either of the TMUX110x devices.

+

±

+

±

OP AMP

OP AMP

TMUX110x

V

OUT

SEL

C

H

DAC

C

L

R

L

(1.8V Capable Control Logic)

Figure 9-1. Single Channel Sample-and-Hold Circuit Example

An optional op amp is used before the switch since driving large capacitive loads is a typical limitation of buffered

DACs. The additional buffer stage is included following the DAC to prevent potential stability problems from

driving a large capacitive load.

Generally, the switch delivers only the input signals to the holding capacitors. However, when the switch is

toggled, some amount of charge is transferred to the switch output in the form of charge injection, resulting in a

pedestal sampling error. The TMUX1101 and TMUX1102 switches have excellent charge injection performance

of only -1.5pC, making them excellent choices for this implementation to minimize sampling error. The pedestal

error voltage is indirectly related to the size of the capacitance on the output, for better precision a larger

capacitor is required due to charge injection.

TMUX1101, TMUX1102

SCDS410D – MARCH 2019 – REVISED FEBRUARY 2024

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