Datasheet

Electrical characteristics STM32F103xF, STM32F103xG
102/120 Doc ID 16554 Rev 3
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 63. R
AIN
max for f
ADC
= 14 MHz
(1)
1. Guaranteed by design, not tested in production.
T
s
(cycles) t
S
(µs) R
AIN
max (kΩ)
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
Table 64. ADC accuracy - limited test conditions
(1)(2)
1. ADC DC accuracy values are measured after internal calibration.
2. 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 5.3.14 does not
affect the ADC accuracy.
Symbol Parameter Test conditions Typ Max
(3)
3. Based on characterisation, not tested in production.
Unit
ET Total unadjusted error 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 ±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
R
AIN
T
S
f
ADC
C
ADC
2
N2+
()ln××
--------------------------------------------------------------- - R
ADC
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