TDA5200 Datasheet, PDF (26/43 Pages) Infineon Technologies AG – ASK Single Conversion Receiver

TDA 5200
Applications
4.4 Quartz Frequency Calculation
The quartz frequency is calculated by using the following formula:
ƒ_QU = (ƒ_RF ± 10.7) / r
(1),
with
ƒ_RF .... receive frequency
ƒ_LO .... local oscillator (PLL) frequency (ƒ_RF ± 10.7)
ƒ_QU .... quartz oscillator frequency
r .... ratio of local oscillator (PLL) frequency and quartz
frequency as shown in the subsequent table.
Table 4-1 PLL Division Ratio Dependence on States of FSEL and CSEL
FSEL
CSEL
Ratio r = (f_LO/f_QU)
open
open
64
open
GND
32
GND
open
128
GND
GND
64
Subtraction of 10.7 occurs in case the receive frequency is higher than the
intended local oscillator frequency, addition in case the receive frequency lies
below the local oscillator frequency.
Examples:
f_QU = (868.4MHz −10.7MHz)/ 64 = 13.40156MHz
f_QU = (868.4MHz − 10.7MHz )/128 = 6.7008 MHz
f_QU = (434.2 MHz −10.7MHz)/ 32 = 13.23437 MHz
Wireless Components
4-6
Specification, March 2000