Datasheet

DS9773 Rev 4 55/93
STM32F030x4/x6/x8/xC Electrical characteristics
75
obtained with typical external components specified in Table 34. 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).
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 18. Typical application with a 32.768 kHz crystal
Note: An external resistor is not required between OSC32_IN and OSC32_OUT and it is forbidden
to add one.
Table 34. LSE oscillator characteristics (f
LSE
= 32.768 kHz)
Symbol Parameter Conditions
(1)
1. Refer to the note and caution paragraphs below the table, and to the application note AN2867 “Oscillator
design guide for ST microcontrollers”.
Min
(2)
Typ Max
(2)
2. Guaranteed by design, not tested in production.
Unit
I
DD
LSE current
consumption
low drive capability - 0.5 0.9
µA
medium-low drive capability - - 1
medium-high drive capability - - 1.3
high drive capability - - 1.6
g
m
Oscillator
transconductance
low drive capability 5 - -
µA/V
medium-low drive capability 8 - -
medium-high drive capability 15 - -
high drive capability 25 - -
t
SU(LSE)
(3)
3. t
SU(LSE)
is the startup time measured from the moment it is enabled (by software) to a stabilized
32.768 kHz oscillation is reached. This value is measured for a standard crystal and it can vary significantly
with the crystal manufacturer
Startup time V
DDIOx
is stabilized - 2 - s
MS30253V2
OSC32_IN
OSC32_OUT
Drive
programmable
amplifier
f
LSE
32.768 kHz
resonator
Resonator with integrated
capacitors
C
L1
C
L2