Datasheet

DS9773 Rev 4 53/93
STM32F030x4/x6/x8/xC Electrical characteristics
75
Low-speed external user clock generated from an external source
In bypass mode the LSE oscillator is switched off and the input pin is a standard GPIO.
The external clock signal has to respect the I/O characteristics in Section 6.3.14. However,
the recommended clock input waveform is shown in Figure 16.
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 4 to 32 MHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on design
simulation results obtained with typical external components specified in
Table 33. 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 32. Low-speed external user clock characteristics
Symbol Parameter
(1)
1. Guaranteed by design, not tested in production.
Min Typ Max Unit
f
LSE_ext
User external clock source frequency - 32.768 1000 kHz
V
LSEH
OSC32_IN input pin high level voltage 0.7 V
DDIOx
-V
DDIOx
V
V
LSEL
OSC32_IN input pin low level voltage V
SS
- 0.3 V
DDIOx
t
w(LSEH)
t
w(LSEL)
OSC32_IN high or low time 450 - -
ns
t
r(LSE)
t
f(LSE)
OSC32_IN rise or fall time - - 50
Table 33. HSE oscillator characteristics
Symbol Parameter Conditions
(1)
Min
(2)
Typ Max
(2)
Unit
f
OSC_IN
Oscillator frequency - 4 8 32 MHz
R
F
Feedback resistor - - 200 - kΩ
MS19215V2
V
LSEH
t
f(LSE)
90%
10%
T
LSE
t
t
r(LSE)
V
LSEL
t
w(LSEH)
t
w(LSEL)