STM32F407OE データシートの表示（PDF） - STMicroelectronics
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STM32F407OE Datasheet PDF : 185 Pages
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Electrical characteristics
STM32F405xx, STM32F407xx
Note:
Table 31. HSE 4-26 MHz oscillator characteristics(1) (2)
Symbol
Parameter
Conditions
Min Typ Max Unit
fOSC_IN Oscillator frequency
4
-
26 MHz
RF Feedback resistor
- 200 -
kΩ
IDD HSE current consumption
VDD=3.3 V,
ESR= 30 Ω,
- 449 -
CL=5 pF@25 MHz
µA
VDD=3.3 V,
ESR= 30 Ω,
- 532 -
CL=10 pF@25 MHz
gm Oscillator transconductance
tSU(HSE(3) Startup time
Startup
5
-
- mA/V
VDD is stabilized
-
2
-
ms
1. Resonator characteristics given by the crystal/ceramic resonator manufacturer.
2. Based on characterization, not tested in production.
3.
toSsUc(iHllaSEtio) nis
the startup
is reached.
time
This
measured from the moment it is enabled
value is measured for a standard crystal
(by software) to
resonator and it
a stabilized 8 MHz
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 25 pF range (typ.), designed for high-frequency applications, and selected to match
the requirements of the crystal or resonator (see Figure 32). 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 electing the crystal, refer to the application note AN2867 “Oscillator
design guide for ST microcontrollers” available from the ST website www.st.com.
Figure 32. Typical application with an 8 MHz crystal
Resonator with
integrated capacitors
CL1
CL2
8 MH z
resonator
REXT(1)
OSC_IN
RF
OSC_OU T
Bias
controlled
gain
fHS E
STM32F
ai17530
1. REXT value depends on the crystal characteristics.
Low-speed external clock generated from a crystal/ceramic resonator
The low-speed external (LSE) clock can be supplied with a 32.768 kHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on
characterization results obtained with typical external components specified in Table 32. 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).
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DocID022152 Rev 4
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