External Clock Source Characteristics; Table 31. High-Speed External User Clock Characteristics; Figure 14. High-Speed External Clock Source Ac Timing Diagram - STMicroelectronics STM32F031F4 Manual

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Electrical characteristics
6.3.7

External clock source characteristics

High-speed external user clock generated from an external source
In bypass mode the HSE oscillator is switched off and the input pin is a standard GPIO.
The external clock signal has to respect the I/O characteristics in
the recommended clock input waveform is shown in
source AC timing
Symbol
f
HSE_ext
V
HSEH
V
HSEL
t
w(HSEH)
t
w(HSEL)
t
r(HSE)
t
f(HSE)
1. Guaranteed by design, not tested in production.
56/113
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diagram.

Table 31. High-speed external user clock characteristics

Parameter
User external clock source frequency
OSC_IN input pin high level voltage
OSC_IN input pin low level voltage
OSC_IN high or low time
OSC_IN rise or fall time

Figure 14. High-speed external clock source AC timing diagram

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Figure 14: High-speed external clock
(1)
Min
-
0.7 V
DDIOx
V
SS
15
-
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STM32F031x4 STM32F031x6
Section 6.3.14. However,
Typ Max
8 32
- V
DDIOx
- 0.3 V
DDIOx
- -
- 20
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Unit
MHz
V
ns