Electrical characteristics
STM32L151xC STM32L152xC
74/135
DocID022799 Rev 10
Low-speed external user clock generated from an external source
The characteristics given in the following table result from tests performed using a low-
speed external clock source, and under the conditions summarized in
.
Figure 16. Low-speed external clock source AC timing diagram
High-speed external clock generated from a crystal/ceramic resonator
The high-speed external (HSE) clock can be supplied with a 1 to 24 MHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on
characterization results obtained with typical external components specified in
. 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 on the resonator
characteristics (frequency, package, accuracy).
Table 28. Low-speed external user clock characteristics
(1)
1. Guaranteed by design, not tested in production
Symbol
Parameter
Conditions
Min
Typ
Max
Unit
f
LSE_ext
User external clock source
frequency
-
1
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
465
-
-
ns
t
r(LSE)
t
f(LSE)
OSC32_IN rise or fall time
-
-
10
C
IN(LSE)
OSC32_IN input capacitance
-
-
0.6
-
pF
069
9/6(+
WI/6(
7/6(
W
WU/6(
9/6(/
WZ/6(+
WZ/6(/