Table 27. Low-Speed External User Clock Characteristics; Figure 15. Low-Speed External Clock Source Ac Timing Diagram - STMicroelectronics STM32L151RE Manual

STM32L151xE STM32L152xE
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.
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

DocID025433 Rev 8
Electrical characteristics
Conditions Min
1
0.7V
DD
- V
SS
465
-
- -
Table 13.
(1)
Typ Max Unit
32.768 1000 kHz
- V
DD
V
- 0.3V
DD
- -
ns
- 10
0.6 - pF
Table 28. In
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