CD00001237 datasheet(90/105 Pages) STMICROELECTRONICS

90 / 105 page

ST6215C ST6225C

90/105

8-BIT ADC CHARACTERISTICS (Cont’d)

ADC Accuracy

Notes:

1. Negative injection disturbs the analog performance of the device. In particular, it induces leakage currents throughout

the device including the analog inputs. To avoid undesirable effects on the analog functions, care must be taken:

- Analog input pins must have a negative injection less than 1mA (assuming that the impedance of the analog voltage

is lower than the specified limits).

- Pure digital pins must have a negative injection less than 1mA. In addition, it is recommended to inject the current as

far as possible from the analog input pins.

2. Data based on characterization results over the whole temperature range, monitored in production.

Figure 73. ADC Accuracy Characteristics

Note: ADC not present on some devices. See device summary on page 1.

Symbol

Parameter

Conditions

Min

Typ.

Max

Unit

|ET|

Total unadjusted error 1)

VDD=5V

fOSC=8MHz

1.2

±2, fosc>1.2MHz

±4, fosc>32KHz

LSB

Offset error 1)

0.72

Gain Error 1)

-0.31

|ED|

Differential linearity error 1)

0.54

|EL|

Integral linearity error 1)

1LSBIDEAL

1LSB

IDEAL

DDA

SSA

–

256

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

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

255

254

253

234567

253 254 255 256

(1)

(2)

(3)

VDDA

VSSA

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