AN1711 datasheet(33/40 Pages) STMICROELECTRONICS

Part #	AN1711

Description	SOFTWARE TECHNIQUES FOR COMPENSATING ST7 ADC ERRORS

PDF	40 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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SOFTWARE TECHNIQUES FOR COMPENSATING ST7 ADC ERRORS

Figure 21. Illustration of calibration

4.2.7 Calibration for Errors using 2 different zones

We can extend the technique mentioned above to do 2-zone calibration. This is required be-

cause of the linear distribution of errors from offset error to mid-voltage and then from mid-

voltage to gain error as shown in Figure 22.

Figure 22. Calibration for 2 zones

In addition to approximate Offset and Gain errors we need to calculate the error around the

center of the analog voltage range. A small voltage range around mid-voltage is to be ignored

Recorded

value

Calibrated

value

VSSA

1023

Digital

output

(Decimal

steps)

Actual

transfer curve

Ideal

transfer curve

Vin

Ideal range

Gain error (negative)

Offset

Error (positive)

509

517

**Graph not to scale

uncalibrated

range

AN1711 Datasheet(PDF) 33 Page - STMicroelectronics