External Clock Source Characteristics; Table 29. High-Speed External User Clock Characteristics; Figure 13. High-Speed External Clock Source Ac Timing Diagram - STMicroelectronics STM32F050G6 Manual

Electrical characteristics
6.3.6

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
the recommended clock input waveform is shown in
Table 29.
Symbol
f
HSE_ext
V
HSEH
V
HSEL
t
w(HSEH)
t
w(HSEL)
t
r(HSE)
t
f(HSE)
1. Guaranteed by design, not tested in production.

Figure 13. High-speed external clock source AC timing diagram

V HSEH
V HSEL
52/98
High-speed external user clock characteristics
Parameter
User external clock source
frequency
OSC_IN input pin high level voltage
OSC_IN input pin low level voltage
OSC_IN high or low time
OSC_IN rise or fall time
90%
10%
t r(HSE)
Doc ID 023079 Rev 3
Figure
(1)
Conditions
t W(HSEH)
t f(HSE)
T HSE
STM32F050xx
Section 6.3.13. However,
13.
Min Typ Max
1 8 32
0.7V - V
DD DD
V - 0.3V
SS
15 - -
- - 20
t W(HSEL)
MS19214V2
Unit
MHz
V
DD
ns
t