Datasheet
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STM32L431xx Electrical characteristics
168
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 21.
Figure 21. Low-speed external clock source AC timing diagram
Table 44. Low-speed external user clock characteristics
(1)
Symbol Parameter Conditions Min Typ Max Unit
f
LSE_ext
User external clock source frequency - - 32.768 1000 kHz
V
LSEH
OSC32_IN input pin high level voltage - 0.7 V
DDIOx
-V
DDIOx
V
V
LSEL
OSC32_IN input pin low level voltage - V
SS
-0.3 V
DDIOx
t
w(LSEH)
t
w(LSEL)
OSC32_IN high or low time - 250 - - ns
1. Guaranteed by design.
069
9
/6(+
W
I/6(
7
/6(
W
W
U/6(
9
/6(/
W
Z/6(+
W
Z/6(/
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