External Clock Source Characteristics; Table 34. High-Speed External User Clock Characteristics; Figure 15. High-Speed External Clock Source Ac Timing Diagram - STMicroelectronics STM32F042G4 Manual

STM32F042xx
6.3.7

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
source AC timing
Symbol
f User external clock source frequency
HSE_ext
V OSC_IN input pin high level voltage
HSEH
V OSC_IN input pin low level voltage
HSEL
t
w(HSEH)
OSC_IN high or low time
t
w(HSEL)
t
r(HSE)
OSC_IN rise or fall time
t
f(HSE)
1. Guaranteed by design, not tested in production.
diagram.

Table 34. High-speed external user clock characteristics

(1)
Parameter

Figure 15. High-speed external clock source AC timing diagram

DocID025832 Rev 2
Figure 15: High-speed external clock
Conditions Min
- -
- 0.7 V
DDIOx
- V
SS
- 15
- -
Electrical characteristics
Section 6.3.14. However,
Typ Max Unit
8 32 MHz
- V
DDIOx
- 0.3 V
DDIOx
- -
- 20
63/117
V
ns
94