TDA5251F1 Datasheet, PDF (57/88 Pages) Infineon Technologies AG – ASK/FSK 315MHz Wireless Transceiver

TDA5251 F1
Version 1.0
Confidential
Application
In case of internal tuning: The crystal on the evaluation board has a temperature stability of +/-
20ppm (or +/- 6.3kHz), which must be added to the total tolerances in worst case. It’s possible to
choose a crystal compensating the oscillators temperature drift in a certain range and thus the
overall temperature tolerances are minimized.
In case of default setup (without internal tuning and without usage of pin 21) the temperature
stability and tuning tolerance of the crystal as well as the tolerance of the external capacitors (+/-
0.1pF) have to be added. The crystal on the evaluation board has a temperature stability of +/-
20ppm (or +/- 6.3kHz) and a tuning tolerance of +/- 10ppm (or +/- 3.2 kHz). The external capacitors
add a tolerance of +/- 3.5ppm (or +/- 1.1kHz). Here also the overall temperature tolerances can be
reduced when applying an appropriate temperature drift of the crystal.
The frequency stabilities of both the receiver and the transmitter and the modulation bandwidth set
the limit for the bandwidth of the IQ filter. To achieve a high receiver sensitivity and efficient
suppression of adjacent interference signals, the narrowest possible IQ bandwidth should be
realized (see Section 3.3).
3.3
IQ-Filter
The IQ-Filter should be set to values corresponding to the RF-bandwidth of the received RF signal
via the D1 to D3 bits of the LPF register (subaddress 03H).
Table 3-9
D3
3dB cutoff frequencies I/Q Filter
D2
D1
nominal f_-3dB in kHz
(programmable)
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
not used
350
250
200
150 (default)
100
50
not used
resulting effective
channel
bandwidth in kHz
700
500
400
300
200
100
Preliminary Specification
57
2003-02-18