Datasheet

Electrical characteristics STM32F303x6/x8
66/121 DocID025083 Rev 7
Figure 14. 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 6.3.14. However, the
recommended clock input waveform is shown in Figure 15.
Table 38. High-speed external user clock characteristics
Symbol Parameter Conditions Min. Typ. Max. Unit
f
HSE_ext
User external clock source
frequency
(1)
1. Guaranteed by design, not tested in production.
-
1832MHz
V
HSEH
OSC_IN input pin high-level voltage 0.7V
DD
-V
DD
V
V
HSEL
OSC_IN input pin low-level voltage V
SS
-0.3V
DD
t
w(HSEH)
t
w(HSEL)
OSC_IN high or low time
(1)
15 - -
ns
t
r(HSE)
t
f(HSE)
OSC_IN rise or fall time
(1)
--20
Table 39. Low-speed external user clock characteristics
Symbol Parameter Conditions Min. Typ. Max. Unit
f
LSE_ext
User External clock source
frequency
(1)
1. Guaranteed by design, not tested in production.
-
- 32.768 1000 kHz
V
LSEH
OSC32_IN input pin high-level
voltage
0.7V
DD
-V
DD
V
V
LSEL
OSC32_IN input pin low-level
voltage
V
SS
-0.3V
DD
t
w(LSEH)
t
w(LSEL)
OSC32_IN high or low time
(1)
450 - -
ns
t
r(LSE)
t
f(LSE)
OSC32_IN rise or fall time
(1)
--50
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