Datasheet

STM32F103xx Electrical characteristics
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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).
Table 45. R
AIN
max for f
ADC
= 14 MHz
(1)
1. Data guaranteed by design, not tested in production.
T
s
(cycles) t
S
(µs) R
AIN
max (kΩ)
1.5 0.11 1.2
7.5 0.54 10
13.50.9619
28.52.0441
41.52.9660
55.53.9680
71.55.11104
239.5 17.1 350
Table 46. ADC accuracy - limited test conditions
(1)
1. ADC DC accuracy values are measured after internal calibration.
Symbol Parameter Test conditions Typ Max
(2)
2. Data based on characterization, not tested in production.
Unit
ET Total unadjusted error
(3)
3. ADC Accuracy vs. Negative Injection Current: Injecting negative current on any of the standard (non-
robust) analog input pins should be avoided as this significantly reduces the accuracy of the conversion
being performed on another analog input. It is recommended to add a Schottky diode (pin to ground) to
standard analog pins which may potentially inject negative current.
Any positive injection current within the limits specified for I
INJ(PIN)
and ΣI
INJ(PIN)
in Section 5.3.12 does not
affect the ADC accuracy.
f
PCLK2
= 56 MHz,
f
ADC
= 14 MHz, R
AIN
< 10 kΩ,
V
DDA
= 3 V to 3.6 V
T
A
= 25 °C
Measurements made after
ADC calibration
V
REF+
= V
DDA
±1.3 ±2
LSB
EO Offset error
(3)
±1 ±1.5
EG Gain error
(3)
±0.5 ±1.5
ED Differential linearity error
(3)
±0.7 ±1
EL Integral linearity error
(3)
±0.8 ±1.5
R
AIN
t
S
f
ADC
C
ADC
2
N2+
()ln××
--------------------------------------------------------------- - R
ADC
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