TSC2012IST datasheet(25/50 Pages) STMICROELECTRONICS

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Output common mode range

The TSC2011 output common mode voltage level can be set thanks to voltages applied on the Vref1 and Vref2

pins. These two pins allow the device to be set either in bidirectional or in unidirectional operation. The voltage

applied to those pins must not exceed the Vcc range. The different configurations are detailed in the section

Unidirectionnal/Bidirectionnal operation.

As depicted by the Figure 57. Vref powered by an external voltage source, Vref1 and Vref2 pins can be driven by

an external voltage source capable of sourcing/sinking a current following the equation below:

Iref= Vicm−Vref

5kΩ+275kΩ+25kΩ

(1)

Figure 57. Vref powered by an external voltage source

When the output common mode voltage is supplied by an external power supply, in order to improve the output

voltage measurement, it is recommended to measure the Vout differentially with respect to Vref voltage. It provides

a better CMRR measurement, better noise immunity and also a more accurate Vout voltage. A decoupling

capacitance of 1 nF minimum can be also added to better filter the power supply, and can also be used as a tank

capacitance in case an ADC is connected to this reference voltage.

TSC2010, TSC2011, TSC2012

Application information

DS13057 - Rev 7

page 25/50

TSC2012IST Fiches technique(PDF) 25 Page - STMicroelectronics