Electrical characteristics
STM32F302xx/STM32F303xx
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 40. 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 40. HSE oscillator characteristics
Symbol
Parameter
Conditions(1)
Min(2) Typ Max(2) Unit
fOSC_IN Oscillator frequency
4
-
8
200
-
32
MHz
RF
Feedback resistor
kΩ
During startup(3)
-
8.5
-
V
DD=3.3 V, Rm= 30Ω,
CL=10 pF@8 MHz
-
-
-
-
-
0.4
0.5
0.8
1
VDD=3.3 V, Rm= 45Ω,
CL=10 pF@8 MHz
-
-
-
-
IDD
HSE current consumption
mA
VDD=3.3 V, Rm= 30Ω,
CL=10 pF@32 MHz
VDD=3.3 V, Rm= 30Ω,
CL=10 pF@32 MHz
V
DD=3.3 V, Rm= 30Ω,
CL=10 pF@32 MHz
1.5
gm
Oscillator transconductance
Startup time
Startup
10
-
-
-
-
mA/V
ms
(4)
tSU(HSE)
VDD is stabilized
2
1. Resonator characteristics given by the crystal/ceramic resonator manufacturer.
2. Guaranteed by design, not tested in production.
3. This consumption level occurs during the first 2/3 of the tSU(HSE) startup time
4. tSU(HSE) is the startup time measured from the moment it is enabled (by software) to a stabilized 8 MHz
oscillation is reached. This value is measured for a standard crystal resonator and it can vary significantly
with the crystal manufacturer
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Doc ID 023353 Rev 5
STMICROELECTRONICS [ ST ]
