TDA5230 Datasheet, PDF (76/186 Pages) Infineon Technologies AG – Universal Low Power ASK/FSK Single Conversion Multi-Channel Image-Reject Receiver

TDA523x
Functional Description
Peak Detector 2 is used to measure RSSI independent of a data transfer and to digitally
trim RSSI. It is read via SFR RSSI2.
Observation of the RSSI signal is active whenever the RX-RUN signal is high. The
RSSI2 register is refreshed and Peak Detector 2 is reset after every read access to
RSSI2.
It may be required to read RSSI2 twice to obtain the required result. This is because, for
example, during a trim procedure input signal power is reduced, after reading RSSI2, the
peak detector will still hold the higher RSSI level. After reading RSSI2 the lower RSSI
level is loaded into the Peak Detector, and can be read by reading RSSI2 again.
When the RX-RUN signal is inactive, a read access has no influence to the peak detector
value. The register RSSI2 is reset to 0 at power up reset.
Input
Data-Pattern
Noise
Run-In TSI D0 D1
....
Dn
-1
Dn
Dn
+1
Dn
+2
Dn
+3
....
SPI read out
RSSI1 & RSSI2
internal RSSI1
RSSI1 Register
internal RSSI
FSYNC clears the
internal RSSI1
internal RSSI2 =
RSSI2 Register
internal RSSI
Reset
*1
FSync
*1
n = PKBITPOS ^SPI
*1 Computation Delay due to filtering and signal calculation.
EOM Noise Run-In TSI D0 D1 ....
*1
EOM
*1
FSync
Figure 35 Peak Detector Behavior
The following figure shows the typical behavior of the digital RSSI. Three curves show
the typical trimming range, the typical default RSSI, and the fourth curve shows a
typically trimmed RSSI.
Data Sheet
72
Version 4.0, 2007-06-01