STMicroelectronics STM32F042C6, Manual

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Electrical characteristics STM32F042x4 STM32F042x6
80/117 DocID025832 Rev 5
Equation 1: R
AIN
max formula
The formula above (
Equation 1
) is used to determine the maximum external impedance
allowed for an error below 1/4 of LSB. Here N = 12 (from 12-bit resolution).
R
AIN
T
S
f
ADC
C
ADC
2
N 2 +
( )
ln
× ×
----------------------------------------------------------------
R
ADC
–
<
Table 55. R
AIN
max for f
ADC
= 14 MHz
T
s
(cycles) t
S
(µs) R
AIN
max (k
Ω
)
(1)
1.5 0.11 0.4
7.5 0.54 5.9
13.5 0.96 11.4
28.5 2.04 25.2
41.5 2.96 37.2
55.5 3.96 50
71.5 5.11 NA
239.5 17.1 NA
1. Guaranteed by design, not tested in production.
Table 56. ADC accuracy
(1)(2)(3)
Symbol Parameter Test conditions Typ Max
(4)
Unit
ET Total unadjusted error
f
PCLK
= 48 MHz,
f
ADC
= 14 MHz, R
AIN
< 10 k Ω
V
DDA
= 3 V to 3.6 V
T
A
= 25 °C
±1.3 ±2
LSB
EO Offset error ±1 ±1.5
EG Gain error ±0.5 ±1.5
ED Differential linearity error ±0.7 ±1
EL Integral linearity error ±0.8 ±1.5
ET Total unadjusted error
f
PCLK
= 48 MHz,
f
ADC
= 14 MHz, R
AIN
< 10 k Ω
V
DDA
= 2.7 V to 3.6 V
T
A
=
-
40 to 105 °C
±3.3 ±4
LSB
EO Offset error ±1.9 ±2.8
EG Gain error ±2.8 ±3
ED Differential linearity error ±0.7 ±1.3
EL Integral linearity error ±1.2 ±1.7
ET Total unadjusted error
f
PCLK
= 48 MHz,
f
ADC
= 14 MHz, R
AIN
< 10 k Ω
V
DDA
= 2.4 V to 3.6 V
T
A
= 25 °C
±3.3 ±4
LSB
EO Offset error ±1.9 ±2.8
EG Gain error ±2.8 ±3
ED Differential linearity error ±0.7 ±1.3
EL Integral linearity error ±1.2 ±1.7
1. ADC DC accuracy values are measured after internal calibration.