Table 27. Low-Speed External User Clock Characteristics; Figure 15. Low-Speed External Clock Source Ac Timing Diagram - ST STM32L15 QC Series Datasheet

STM32L151xC/C-A STM32L152xC/C-A
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
Symbol
f
LSE_ext
V
LSEH
V
LSEL
t
w(LSEH)
t
w(LSEL)
t
r(LSE)
t
f(LSE)
C
IN(LSE)
1. Guaranteed by design.
V LSEH
V LSEL
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
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 27. Low-speed external user clock characteristics

Parameter
User external clock source
frequency
OSC32_IN input pin high level
voltage
OSC32_IN input pin low level
voltage
OSC32_IN high or low time
OSC32_IN rise or fall time
OSC32_IN input capacitance

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

90%
10%
t r(LSE)
DS10262 Rev 8
Conditions
-
-
t w(LSEH)
t f(LSE)
T LSE
Electrical characteristics
Table 13.
(1)
Min Typ Max
1 32.768 1000
0.7V - V
DD DD
V - 0.3V
SS
465 - -
- - 10
- 0.6 -
t w(LSEL)
MS19215V2
Table
Unit
kHz
V
DD
ns
pF
t
28. In
77/134
113