TDA5230 Datasheet, PDF (28/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

TDA523x
Functional Description
The crystal frequency is calculated:
For TDA5230 (Lo Side LO Injection)
f_sys=A*(f_RF-10.7MHz)/64
For TDA5231 (Hi Side LO Injection
f_sys=A*(f_RF+10.7MHz)/64
Values for A depend on the frequency band: 302...320MHz...A=3 (TDA5231),
433...450MHz...A=2, 865...870MHz...A=1 (TDA5230)
The crystal frequency is automatically calculated by the IAF TDA523x
Configuration Tool.
Recommended Trimming Procedure
• Set the TDA523x to SLEEP mode
• Set the registers XTCAL0 and XTCAL1 to the expected nominal values
• Set the TDA523x to Slave Mode Run
• Set the register bit XTALTREN in register CMC1
• Wait for 0.5ms minimum
• Trim the oscillator by increasing and decreasing the values of XTALCAL0/1
• Never change the trim capacitor size by more than 1 pF!
• When the Oscillator is trimmed, reset the XALTREN bit
• Set the TDA523x to SLEEP mode
• Add the settings of XTCAL0/1 to the configuration. It must be set after every power
up or brown out!
Using the High Precision Mode
As discussed earlier, the TDA523x allows to the crystal oscillator to be trimmed by the
use of internal trim capacitors. It is also possible to use the trim functionality to
compensate temperature drift of crystals.
During Run Mode (always when the receiver is active) the capacitors are automatically
connected and the oscillator is used in the High Precision Mode.
On entering Sleep Mode, the capacitors are automatically disconnected to save power.
If the High Precision Mode is also required for Sleep Mode, the automatic disconnection
of trim capacitors can be avoided by setting XALTREN to 1 (enable XTAL trim).
Setting of XALTREN has to be changed only in Run-Mode!
Data Sheet
24
Version 4.0, 2007-06-01