STM32F301x6 STM32F301x8
Electrical characteristics
Low-speed external user clock generated from an external source
In bypass mode the LSE 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 15
Table 40. Low-speed external user clock characteristics
Symbol
Parameter
Conditions
Min
Typ
Max Unit
fLSE_ext
User External clock source
frequency(1)
VLSEH
OSC32_IN input pin high level
voltage
VLSEL
OSC32_IN input pin low level
voltage
-
tw(LSEH)
tw(LSEL)
OSC32_IN high or low time(1)
tr(LSE)
tf(LSE)
OSC32_IN rise or fall time(1)
1. Guaranteed by design, not tested in production.
-
32.768 1000 kHz
0.7VDD
-
VDD
V
VSS
-
0.3VDD
450
-
-
-
-
ns
50
Figure 15. Low-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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