TDA7110F Datasheet, PDF (23/36 Pages) Infineon Technologies AG – 434 MHz ASK/FSK Transmitter in 10-pin Package

TDA7110F
Example for the FSK-Mode:
Applications
FSK modulation is achieved by switching the load capacitance of the crystal as shown
below.
FSKDTA
FSKOUT
Csw
-R
L
f, CL Cv1
Cv2
COSC
IC
Figure 12 FSK Mode
The frequency deviation of the crystal oscillator is multiplied with the divider factor N of
the Phase Locked Loop to the output of the power amplifier. In case of small frequency
deviations (up to +/- 1000 ppm), the two desired load capacitances can be calculated
with the formula below.
CL±
=
CL m C
1±
0 ^Δf (1 + ^{2(C0 + CL)}
N* f1
C1
Δf _{(1 +} 2(C0 + CL))
)
N* f1
C1
C_L:
crystal load capacitance for nominal frequency
C₀:
shunt capacitance of the crystal
f:
frequency
ω:
ω = 2πf: angular frequency
N:
division ratio of the PLL
df:
peak frequency deviation
Because of the inductive part of the TDA7110F, these values must be corrected by
Formula 1 on the preceding page. The value of Cv± can be calculated.
Data Sheet
23
V 1.0, 2009-02-26