STM32L452XX Datasheet, PDF (127/210 Pages) STMicroelectronics – Ultra-low-power with FlexPowerControl

STM32L452xx
Electrical characteristics
Note:
For information on selecting the crystal, refer to the application note AN2867 “Oscillator
design guide for ST microcontrollers” available from the ST website www.st.com.
Figure 20. Typical application with an 8 MHz crystal
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1. R_EXT value depends on the crystal characteristics.
Low-speed external clock generated from a crystal resonator
069
The low-speed external (LSE) clock can be supplied with a 32.768 kHz crystal resonator
oscillator. All the information given in this paragraph are based on design simulation results
obtained with typical external components specified in Table 57. 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).
Symbol
Table 57. LSE oscillator characteristics (f_LSE = 32.768 kHz)⁽¹⁾
Parameter
Conditions⁽²⁾
Min Typ
LSEDRV[1:0] = 00
Low drive capability
I_DD(LSE)
LSEDRV[1:0] = 01
Medium low drive capability
LSE current consumption
LSEDRV[1:0] = 10
Medium high drive capability
LSEDRV[1:0] = 11
High drive capability
LSEDRV[1:0] = 00
Low drive capability
Gm_critmax
Maximum critical crystal
gm
LSEDRV[1:0] = 01
Medium low drive capability
LSEDRV[1:0] = 10
Medium high drive capability
t_SU(LSE)(3) Startup time
LSEDRV[1:0] = 11
High drive capability
V_DD is stabilized
- 250
- 315
- 500
- 630
-
-
-
-
-
-
-
-
-
2
Max Unit
-
-
nA
-
-
0.5
0.75
µA/V
1.7
2.7
-
s
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