Calibration and linearization technique

AN1798

8/16

3.2

Hardware implementation

In order to calibrate the ADC, apply two stable voltage sources and read these values to

obtain the dynamic of the ADC.

This can be done by applying the 2.5 V source to one of four ADC channels (for example

AIN1) and connecting the ground to another channel (for example AIN0). Two channels are

reserved for hardware calibration.

It is possible to obtain the 2.5 V source by a zener diode (ex: TS824-2.5) and a dedicated

resistor.

The following figure shows the calibration hardware implementation:

Figure 5.

Calibration hardware implementation

= 1.6K

3.3 V

AIN2

AIN3

R1

1.6K

AIN1

AIN0

two available input channels

STR71x

D1(*)

(*) D1 ex: TS824-2.5

two channels for calibration

0.1µF

AGND

AVDD

3.3 V