ST72C171 Datasheet, PDF (140/152 Pages) STMicroelectronics – 8-BIT MCU with 8K FLASH, ADC, WDG, SPI, SCI, TIMERS SPGAs Software Programmable Gain Amplifiers, OP-AMP

ST72C171
8-BIT ADC CHARACTERISTICS (Cont’d)
ADC Accuracy
Symbol
|E_T|
E_O
E_G
|E_D|
|E_L|
Parameter
Total unadjusted error ¹⁾
Offset error ¹⁾
Gain Error ¹⁾
Differential linearity error ¹⁾
Integral linearity error ¹⁾
Conditions
V_DD=5.0V, ³⁾
f_CPU=8MHz
Min Max Unit
1
-0.5
0.5
-0.5
0.5
LSB
0.5
0.5
Figure 98. ADC Accuracy Characteristics
Digital Result ADCDR
255
254
253
1LSBIDEAL
=
V-----D-----D----A------–_{----V-----S----S-----A--}
256
(2)
7
E_T
(3)
6
5
E_O
E_L
4
3
E_D
2
1
1 LSB_IDEAL
E_G
(1)
0
1234567
V_SSA
253 254 255 256
V_DDA
(1) Example of an actual transfer curve
(2) The ideal transfer curve
(3) End point correlation line
E_T=Total Unadjusted Error: maximum deviation
between the actual and the ideal transfer curves.
E_O=Offset Error: deviation between the first actual
transition and the first ideal one.
E_G=Gain Error: deviation between the last ideal
transition and the last actual one.
E_D=Differential Linearity Error: maximum deviation
between actual steps and the ideal one.
E_L=Integral Linearity Error: maximum deviation
between any actual transition and the end point
correlation line.
V_in (LSB_IDEAL)
Notes:
1. ADC Accuracy vs. Negative Injection Current:
For I_INJ-=0.8mA, the typical leakage induced inside the die is 1.6µA and the effect on the ADC accuracy is a loss of 1 LSB
for each 10KΩ increase of the external analog source impedance. This effect on the ADC accuracy has been observed
under worst-case conditions for injection:
- negative injection
- injection to an Input with analog capability, adjacent to the enabled Analog Input
- at 5V V_DD supply, and worst case temperature.
3. Data based on characterization results over the whole temperature range, monitored in production.
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