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CD00191174 Datasheet, PDF (54/112 Pages) STMicroelectronics – High-density access line, ARM-based 32-bit MCU
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Electrical characteristics
STM32F101xC, STM32F101xD, STM32F101xE
Note:
Caution:
For CL1 and CL2, it is recommended to use high-quality ceramic capacitors in the 5 pF to
15 pF range selected to match the requirements of the crystal or resonator. CL1 and CL2, are
usually the same size. The crystal manufacturer typically specifies a load capacitance which
is the series combination of CL1 and CL2.
Load capacitance CL has the following formula: CL = CL1 x CL2 / (CL1 + CL2) + Cstray where
Cstray is the pin capacitance and board or trace PCB-related capacitance. Typically, it is
between 2 pF and 7 pF.
To avoid exceeding the maximum value of CL1 and CL2 (15 pF) it is strongly recommended
to use a resonator with a load capacitance CL ≤ 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 CL = 6 pF, and Cstray = 2 pF,
then CL1 = CL2 = 8 pF.
Figure 20. Typical application with a 32.768 kHz crystal
Resonator with
integrated capacitors
CL1
OSC32_IN
32.768 KH z
resonator
RF
OSC32_OU T
CL2
Bias
controlled
gain
fLSE
STM32F10xxx
ai14129b
5.3.7
Internal clock source characteristics
The parameters given in Table 25 are derived from tests performed under ambient
temperature and VDD supply voltage conditions summarized in Table 10.
High-speed internal (HSI) RC oscillator
Table 25. HSI oscillator characteristics(1)
Symbol
Parameter
Conditions
Min Typ Max Unit
fHSI Frequency
DuCy(HSI) Duty cycle
45
User-trimmed with the RCC_CR
register(2)
8
MHz
55 %
1(3)
%
ACCHSI
tsu(HSI)(4)
Accuracy of the HSI
oscillator
HSI oscillator startup
time
TA = –40 to 105 °C
Factory-
TA = –10 to 85 °C
calibrated(4) TA = 0 to 70 °C
TA = 25 °C
–2
–1.5
–1.3
–1.1
1
2.5 %
2.2 %
2
%
1.8 %
2
µs
IDD(HSI)(4)
HSI oscillator power
consumption
80 100 µA
1. VDD = 3.3 V, TA = –40 to 85 °C unless otherwise specified.
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Doc ID 14610 Rev 8
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