ST7232A datasheet(138/154 Pages) STMICROELECTRONICS

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ST7232A

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10-BIT ADC CHARACTERISTICS (Cont’d)

12.12.3 ADC Accuracy

Conditions: VDD=5V

Notes:

1. ADC Accuracy vs. Negative Injection Current: Injecting negative current may reduce the accuracy of the conversion

being performed on another analog input. The effect of negative injection current on robust pins is specified in Section

12.12.

Any positive injection current within the limits specified for IINJ(PIN) and ΣIINJ(PIN) in Section 12.8 does not affect the ADC

accuracy.

2. Data based on characterization results, monitored in production to guarantee 99.73% within ± max value from -40°C

to 125°C ( ± 3

σ distribution limits).

Figure 82. ADC Accuracy Characteristics

Symbol

Parameter

Conditions

Typ

Max2)

Unit

|ET|

Total unadjusted error 1)

LSB

|EO|

Offset error 1)

|EG|

Gain Error 1)

0.5

4.5

|ED|

Differential linearity error 1)

CPU in run mode @ fADC = 2 MHz.

1.5

4.5

|EL|

Integral linearity error 1)

CPU in run mode @ fADC = 2 MHz.

1.5

4.5

1LSBIDEAL

1LSB

IDEAL

AREF

SSA

–

1024

--------------------------------------------

Vin (LSBIDEAL)

(1) Example of an actual transfer curve

(2) The ideal transfer curve

(3) End point correlation line

ET=Total Unadjusted Error: maximum deviation

between the actual and the ideal transfer curves.

EO=Offset Error: deviation between the first actual

transition and the first ideal one.

EG=Gain Error: deviation between the last ideal

transition and the last actual one.

ED=Differential Linearity Error: maximum deviation

between actual steps and the ideal one.

EL=Integral Linearity Error: maximum deviation

between any actual transition and the end point

correlation line.

Digital Result ADCDR

1023

1022

1021

2345

1021 1022 1023 1024

(1)

(2)

(3)

VAREF

VSSA

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