Specifications

ST72325xx
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Figure 76. Typical Application with a Crystal or Ceramic Resonator
1. The relatively low value of the RF resistor, offers a good protection against issues resulting from use in a humid envi-
ronment, due to the induced leakage and the bias condition change. However, it is recommended to take this point into
account if the µC is used in tough humidity conditions.
2. For C
L1
and C
L2
it is recommended to use high-quality ceramic capacitors in the 5-pF to 25-pF range (typ.) designed
for high-frequency applications and selected to match the requirements of the crystal or resonator. C
L1
and C
L2,
are usu-
ally the same size. The crystal manufacturer typically specifies a load capacitance which is the series combination of C
L1
and C
L2
. PCB and MCU pin capacitance must be included when sizing C
L1
and C
L2
(10 pF can be used as a rough esti-
mate of the combined pin and board capacitance).
OSC2
OSC1
f
OSC
C
L1
C
L2
i
2
R
F
ST72XXX
RESONATOR
WHEN RESONATOR WITH
INTEGRATED CAPACITORS
V
DD
/2
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