STMicroelectronics STM32F038C6 - Table 30. Low-Speed External User Clock Characteristics; Figure 13. High-Speed External Clock Source AC Timing Diagram; Figure 14. Low-Speed External Clock Source AC Timing Diagram

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STM32F038x6 Electrical characteristics
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Figure 13. High-speed external clock source AC timing diagram
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 6.3.13. However,
the recommended clock input waveform is shown in Figure 14.
Figure 14. Low-speed external clock source AC timing diagram
Table 30. Low-speed external user clock characteristics
Symbol Parameter
(1)
1. Guaranteed by design, not tested in production.
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 450 - -
ns
t
r(LSE)
t
f(LSE)
OSC32_IN rise or fall time - - 50
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