Electrical characteristics
STM32F030x4 STM32F030x6 STM32F030x8
Note:
High-speed external clock generated from a crystal/ceramic resonator
The high-speed external (HSE) clock can be supplied with a 4 to 32 MHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on design
simulation results obtained with typical external components specified in Table 31. In the
application, the resonator and the load capacitors have to be placed as close as possible to
the oscillator pins in order to minimize output distortion and startup stabilization time. Refer
to the crystal resonator manufacturer for more details on the resonator characteristics
(frequency, package, accuracy).
Symbol
Table 31. HSE oscillator characteristics
Parameter
Conditions(1)
Min(2) Typ Max(2) Unit
fOSC_IN Oscillator frequency
RF Feedback resistor
During startup(3)
4
8
32 MHz
- 200 -
k
-
8.5
IDD HSE current consumption
VDD=3.3 V, Rm= 45,
CL=10 pF@8 MHz
-
0.5
-
mA
VDD=3.3 V, Rm= 30,
CL=20 pF@32 MHz
-
1.5
-
gm Oscillator transconductance
tSU(HSE)(4) Startup time
Startup
VDD is stabilized
10
-
-
2
- mA/V
-
ms
1. Resonator characteristics given by the crystal/ceramic resonator manufacturer.
2. Guaranteed by design, not tested in production.
3. This consumption level occurs during the first 2/3 of the tSU(HSE) startup time
4. tSU(HSE) is the startup time measured from the moment it is enabled (by software) to a
stabilized 8 MHz oscillation is reached. This value is measured for a standard crystal resonator
and it can vary significantly with the crystal manufacturer
For CL1 and CL2, it is recommended to use high-quality external ceramic capacitors in the
5 pF to 20 pF range (typ.), designed for high-frequency applications, and selected to match
the requirements of the crystal or resonator (see Figure 14). 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. PCB and MCU pin capacitance must be included (10 pF
can be used as a rough estimate of the combined pin and board capacitance) when sizing
CL1 and CL2.
For information on selecting the crystal, refer to the application note AN2867 “Oscillator
design guide for ST microcontrollers” available from the ST website www.st.com.
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