Electrical characteristics
STM32F103xC, STM32F103xD, STM32F103xE
C
stray
is the pin capacitance and board or trace PCB-related capacitance. Typically, it is
between 2 pF and 7 pF.
Caution:
To avoid exceeding the maximum value of C
L1
and C
L2
(15 pF) it is strongly recommended
to use a resonator with a load capacitance C
L
7 pF. Never use a resonator with a load
capacitance of 12.5 pF.
Example:
if you choose a resonator with a load capacitance of C
L
= 6 pF, and C
stray
= 2 pF,
then C
L1
= C
L2
= 8 pF.
Figure 23. Typical application with a 32.768 kHz crystal
Resonator with
integrated capacitors
CL1
OSC32_IN
32.768 kH z
resonator
CL2
RF
OSC32_OU T
Bias
controlled
gain
STM32F103xx
fLSE
ai14146
5.3.7
Internal clock source characteristics
The parameters given in
are derived from tests performed under ambient
temperature and V
DD
supply voltage conditions summarized in
High-speed internal (HSI) RC oscillator
Table 25.
Symbol
f
HSI
HSI oscillator characteristics
(1)
Parameter
Frequency
User-trimmed with the RCC_CR
register
(2)
Conditions
Min
Typ
8
1
(3)
–2
–1.5
–1.3
–1.1
1
80
2.5
2.2
2
1.8
2
100
Max
Unit
MHz
%
%
%
%
%
µs
µA
ACC
HSI
Accuracy of the HSI
oscillator
Factory-
calibrated
(4)
T
A
= –40 to 105 °C
T
A
= –10 to 85 °C
T
A
= 0 to 70 °C
T
A
= 25 °C
t
su(HSI)(4)
I
DD(HSI)(4)
HSI oscillator
startup time
HSI oscillator power
consumption
1. V
DD
= 3.3 V, T
A
= –40 to 105 °C unless otherwise specified.
2. Refer to application note AN2868 “STM32F10xxx internal RC oscillator (HSI) calibration” available from
the ST website www.st.com.
3. Guaranteed by design, not tested in production.
4. Based on characterization, not tested in production.
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