STM32F301x6 STM32F301x8
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 Section 6.3.14. However, the
recommended clock input waveform is shown in Figure 14.
Table 40. High-speed external user clock characteristics
Symbol
Parameter
Conditions
Min Typ Max Unit
fHSE_ext
User external clock source
frequency(1)
1
8
32 MHz
VHSEH OSC_IN input pin high level voltage
0.7VDD -
VDD
V
VHSEL OSC_IN input pin low level voltage
-
VSS
- 0.3VDD
tw(HSEH)
tw(HSEL)
tr(HSE)
tf(HSE)
OSC_IN high or low time(1)
OSC_IN rise or fall time(1)
15
-
-
ns
-
-
20
1. Guaranteed by design.
Figure 14. High-speed external clock source AC timing diagram
9+6(+
9+6(/
WU+6(
WZ+6(+
WI+6(
7+6(
WZ+6(/
W
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