Datasheet

External clock sources and timing characteristics10.3.3
HSE user external clock
Subject to general operating conditions for V
DD
and T
A
.
Table 34: HSE user external clock characteristics
UnitMaxMinConditionsParameterSymbol
MHz160
User external clock source
frequency
f
HSE_ext
V
V
DD
+ 0.3 V0.7 x V
DD
OSCIN input pin high level
voltage
V
HSEH
(1)
0.3 x V
DD
V
SS
OSCIN input pin low level
voltage
V
HSEL
(1)
μA+1-1
V
SS
< V
IN
< V
DD
OSCIN input leakage currentI
LEAK_HSE
(1)
Data based on characterization results, not tested in production.
Figure 18: HSE external clocksource
V
HSEH
V
HSEL
External clock
source
OSCIN
f
HSE
STM8
HSE crystal/ceramic resonator oscillator
The HSE clock can be supplied with a 1 to 16 MHz crystal/ceramic resonator oscillator. All
the information given in this paragraph is based on characterization results with specified
typical external components. In the application, the resonator and the load capacitors have
to be placed as close as possible to the oscillator pins in order to minimize output distortion
and start-up stabilization time. Refer to the crystal resonator manufacturer for more details
(frequency, package, accuracy...).
Table 35: HSE oscillator characteristics
UnitMaxTypMinConditionsParameterSymbol
MHz16-1
External high speed
oscillator frequency
f
HSE
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Electrical characteristicsSTM8S903K3 STM8S903F3