TSU102 datasheet(21/33 Pages) STMICROELECTRONICS

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TSU101, TSU102, TSU104

Application information

4.7

Using the TSU10x series with sensors

The TSU10x series has MOS inputs, thus input bias currents can be guaranteed down to

5 pA maximum at ambient temperature. This is an important parameter when the

operational amplifier is used in combination with high impedance sensors.

The TSU101, TSU102, and TSU104 series is perfectly suited for trans-impedance

configuration as shown in Figure 39. This configuration allows a current to be converted into

a voltage value with a gain set by the user. It is an ideal choice for portable electrochemical

gas sensing or photo/UV sensing applications. The TSU10x series, using trans-impedance

configuration, is able to provide a voltage value based on the physical parameter sensed by

the sensor.

Electrochemical gas sensors

The output current of electrochemical gas sensors is generally in the range of tens of nA to

hundreds of

μA. As the input bias current of the TSU101, TSU102, and TSU104 is very low

(see Figure 9, Figure 10, and Figure 11) compared to these current values, the TSU10x

series is well adapted for use with the electrochemical sensors of two or three electrodes.

Figure 40 shows a potentiostat (electronic hardware required to control a three electrode

cell) schematic using the TSU101, TSU102, and TSU104. In such a configuration, the

devices minimize leakage in the reference electrode compared to the current being

measured on the working electrode.

Figure 39. Trans-impedance amplifier schematic

TSU102 Datenblatt(PDF) 21 Page - STMicroelectronics