TDA5200 Datasheet, PDF (25/43 Pages) Infineon Technologies AG – ASK Single Conversion Receiver

TDA 5200
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
TDA5200
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 pF
13.401 MHz: C_L = 12 pF
X_L=750 Ω
X_L=1250 Ω
C_S = 8.7 pF
C_S = 5.3 pF
These values may be obtained in high accuracy by putting two capacitors in
series to the quartz, such as 20pF and 15pF in the 6.7MHz case and 15pF and
8.2pF in the 13.401MHz case.
Wireless Components
4-5
Specification, March 2000