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DocID15274 Rev 7 75/104
STM32F105xx, STM32F107xx Electrical characteristics
103
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).
t
lat
(2)
Injection trigger conversion latency
f
ADC
= 14 MHz - - 0.214 µs
---3
(4)
1/f
ADC
t
latr
(2)
Regular trigger conversion latency
f
ADC
= 14 MHz - - 0.143 µs
---2
(4)
1/f
ADC
t
S
(2)
Sampling time
f
ADC
= 14 MHz 0.107 - 17.1 µs
- 1.5 - 239.5 1/f
ADC
t
STAB
(2)
Power-up time - 0 0 1 µs
t
CONV
(2)
Total conversion time (including
sampling time)
f
ADC
= 14 MHz 1 - 18 µs
-
14 to 252 (t
S
for sampling +12.5 for
successive approximation)
1/f
ADC
1. Based on characterization, not tested in production.
2. Guaranteed by design, not tested in production.
3. V
REF+
is internally connected to V
DDA
and V
REF-
is internally connected to V
SSA
.
4. For external triggers, a delay of 1/f
PCLK2
must be added to the latency specified in Table 52.
Table 52. ADC characteristics (continued)
Symbol Parameter Conditions Min Typ Max Unit
Table 53. R
AIN
max for f
ADC
= 14 MHz
(1)
1. Based on characterization, 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
R
AIN
T
S
f
ADC
C
ADC
2
N2+
()ln××
--------------------------------------------------------------- - R
ADC
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