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TMUX1101, TMUX1102

SCDS410 – MARCH 2019

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10.3 Design Requirements

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

Table 3. Design parameters

PARAMETERS

VALUES

3.3 V

Input / Output signal range

0 µA to 10 µA

Control logic thresholds

1.8 V compatible

10.4 Detailed Design Procedure

The TMUX110x devices can be operated without any external components except for the supply decoupling

capacitors. All inputs signals passing through the switch must fall within the recommend operating conditions of

the TMUX110x including signal range and continuous current. For this design example, with a supply of 3.3 V,

the signals can range from 0 V to 3.3 V when the device is powered. The max continuous current can be 30 mA.

Photodiodes commonly have a current output that ranges from a few hundred picoamps to tens of microamps

based on the amount of light being absorbed. The TMUX110x have a typical On-leakage current of less than 10

pA which would lead to an accuracy well within 1% of a full scale 10 µA signal. The low ON and OFF

capacitance of the TMUX110x improves system stability by minimizing the total capacitance on the output of the

amplifier. Lower capacitance leads to less overshoot and ringing in the system which can cause the amplifier

circuit to go unstable if the phase margin is not at least 45°. Refer to Improve Stability Issues with Low CON

Multiplexers for more information on calculating the phase margin vs. percent overshoot.