Datasheet

STM8AF52/62xx, STM8AF51/61xx Electrical characteristics
Doc ID 14395 Rev 9 65/110
10.3.3 External clock sources and timing characteristics
HSE external clock
An HSE clock can be generated by feeding an external clock signal of up to 24 MHz to the
OSCIN pin.
Clock characteristics are subject to general operating conditions for V
DD
and T
A
.
Figure 18. HSE external clock source
HSE crystal/ceramic resonator oscillator
The HSE clock can be supplied using a crystal/ceramic resonator oscillator of up to 24 MHz.
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 startup stabilization time. Refer to the crystal resonator manufacturer for more details
(frequency, package, accuracy...).
Table 33. HSE external clock characteristics
Symbol Parameter Conditions Min Typ Max Unit
f
HSE_ext
User external clock source
frequency
T
A
= -40 °C to 150 °C 0
(1)
—24MHz
V
HSEdHL
Comparator hysteresis — 0.1 x V
DD
——
V
V
HSEH
OSCIN high-level input pin
voltage
— 0.7 x V
DD
—V
DD
V
HSEL
OSCIN low-level input pin
voltage
—V
SS
— 0.3 x V
DD
I
LEAK_HSE
OSCIN input leakage current V
SS
< V
IN
< V
DD
-1 — +1 µA
1. If CSS is used, the external clock must have a frequency above 500 kHz.
OSCIN
f
HSE
External clock
STM8A
source
V
HSEL
V
HSEH