STM32F103xx
Electrical characteristics
(1)
Table 39. ADC characteristics
(continued)
Conditions
Symbol
Parameter
Min
Typ
Max
Unit
RAIN
CAIN
External input impedance
kΩ
TBD(2)(3)
External capacitor on analog
input
pF
Negative input leakage current VIN < VSS, | IIN | < 400 µA
Ilkg
5
6
1
5
µA
kΩ
pF
on analog pins
on adjacent analog pin
RADC
CADC
Sampling switch resistance
Internal sample and hold
capacitor
5.9
83
µs
1/fADC
µs
tCAL
Calibration time
fADC = 14MHz
0.214
3
tlat
Injection conversion latency
fADC = 14 MHz
fADC = 14 MHz
1/fADC
µs
tS
Sampling time
Power-up time
0.107
17.1
tSTAB
0
1
0
1
µs
µs
18
Total conversion time (including
sampling time)
14 (1.5 for sampling
+12.5 for successive
approximation)
tCONV
fADC = 14 MHz
1/fADC
1. TBD = to be determined.
2. Depending on the input signal variation (fAIN), CAIN can be increased for stabilization time and reduced to
allow the use of a larger serial resistor (RAIN). It is valid for all fADC frequencies ≤14 MHz.
3. During the sample time the input capacitance CAIN (5 max) can be charged/discharged by the external
source. The internal resistance of the analog source must allow the capacitance to reach its final voltage
level within tS. After the end of the sample time tS, changes of the analog input voltage have no effect on
the conversion result. Values for the sample clock tS depend on programming.
Table 40. ADC accuracy (f
= 14 MHz, f
= 14 MHz, R
<10 kΩ, V
=
DDA
PCLK2
ADC
AIN
(1)
3.3 V)
Symbol
Parameter
Conditions
Typ
Max
Unit
|ET|
|EO|
|EG|
|ED|
|EL|
Total unadjusted error(2)
Offset error(2)
3
1
2
3
2
TBD
TBD
TBD
TBD
TBD
Gain Error(2)
LSB
Differential linearity error(2)
Integral linearity error(2)
1. TBD = to be determined.
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 IINJ(PIN) and ΣIINJ(PIN) in Section 5.3.12 does not
affect the ADC accuracy.
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STMICROELECTRONICS [ ST ]
