TDA5230 Datasheet, PDF (77/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

TDA523x
Functional Description
Typical
Typical RSSI2 over Input Signal Power
250
200
t rim ^{me d}
mminiinmimumumo
ffset,
gain
150
100
50
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0
-125 -115 -105 -95 -85 -75 -65 -55 -45 -35 -25
Input Signal Pow er [dBm ]
Figure 36 Typical Digital RSSI over Input Signal Power
Recommended Digital Trimming Procedure:
• Download configuration file (Run Mode Slave, LIMGAIN, LIMOFFS set to minimum)
• Switch off RF Path by setting register RFC to 0x1F.
• Read RSSI2 eleven times (minimum 10 ms in between readings), use average of last
ten readings (always)
• Change LIMOFFS till RSSI2 readings with no input signal are between 0x02 and
0x05 or closest to the upper value
• Set register RFC to 0x0z to switch on RF-Path (z stands for the selected value for IF
Attenuation. See Chapter 2.4.7 RF Path. If IF Attenuation is trimmed, this has to be
done before trimming of RSSI.).
• Change LIMGAIN till RSSI2 readings at -10 dBm are between 0xFC and 0xFE or
closest to the lower value.
• The new values for LIMGAIN and LIMOFFS have to be added to the configuration!
It is only necessary to use either analog or digital trimming. The results between analog
and digital trimming may differ. Therefore the same procedure should always be used.
Data Sheet
73
Version 4.0, 2007-06-01