TDA5210 Datasheet, PDF (26/53 Pages) Infineon Technologies AG – ASK/FSK Single Conversion Receiver

TDA 5210
Applications
4.3 Quartz Load Capacitance Calculation
The value of the capacitor necessary to achieve that the quartz oscillator is
operating at the intended frequency is determined by the reactive part of the
negative resistance of the oscillator circuit as shown in Section 5.1.3 and by the
quartz specifications given by the quartz manufacturer.
Crystal
C_S
Input
impedance
Z_1-28
Pin 28
TDA5210
Pin 1
Figure 4-4
Quartz_load.wmf
Determination of Series Capacitance Value for the Quartz Oscillator
Crystal specified with load capacitance
C_S
=
1
C_l
1
+ 2π
f
X_L
with C_l the load capacitance (refer to the quartz crystal specification).
Examples:
6.7 MHz: C_L = 12 pFX_L=695ΩC_S = 8.9 pF
13.4 MHz: C_L = 12 pFX_L=1010 ΩC_S = 5.9 pF
These values may be obtained in high accuracy by putting two capacitors in
series to the quartz, such as 22pF and 15pF in the 6.7MHz case and 22pF and
8.2pF in the 13.4MHz case.
Wireless Components
4-5
Specification, May 2001