Figure 29. Input bias current vs. common mode voltage Vcc = 5 V

0

5

10

15

20

25

30

0

5

10

15

20

25

30

-10

0

10

20

30

40

50

-10

0

10

20

30

40

50

T=25°C

Vcc=5V

Vref=2.5V

Vicm (V)

•

Output common mode range

The TSC21x output common mode voltage level can be set thanks to voltages applied on the Vref pin. This pin

allows to set the device either in bidirectional or in unidirectional operation. The voltage applied on this pin must

not exceed the Vcc range. The different configurations are detailed in the chapter Unidirectionnal/Bidirectionnal

operation.

As depicted by Figure 30 and using a TSC210, the Vref pin can be driven by an external voltage source capable

of sourcing/sinking a current following the below equation 1:

Iref=Vicm−Vref

R1+R4 =Vicm−Vref

5kΩ+1MΩ

(1)

Figure 30. Vref powered by an external voltage source with a TSC210

Gnd

VCC

OUT

VREF

In-

In+

+

-

5kΩ

Shunt

resistor

5kΩ

1MΩ

Gnd

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

capacitance of 1 nF minimum can be also added in order 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.

TSC210, TSC211, TSC212, TSC213, TSC214, TSC215

Theory of operation

DS13237 - Rev 6

page 13/38