TDA5225 Datasheet, PDF (35/176 Pages) Infineon Technologies AG – Enhanced Sensitivity Multi-Channel Quad-Configuration Receiver

TDA5225
Functional Description
In case of a Wake-Up, the actual peak value is written in the RSSIPWU register. Even
in case no Wake-Up occurred, actual peak value is written in the RSSIPWU register at
the end of the actual configuration/channel of the Self Polling period. So if no Wake-Up
occurred, then the RSSIPWU register contains the peak value of the last
configuration/channel of the Self Polling period, even in a Multi-Configuration/Multi-
Channel setup. This functionality can be used to track RSSI during unsuccessful Wake-
Up search due to no input signal or due to blocking RSSI detection.
For further details please refer to Chapter 2.4.8.2 Wake-Up Generator and
Chapter 2.6.2 Polling Timer Unit.
Input
Data Pattern
Noise Run-In
SPI read out
RSSIPRX
internal RSSIPRX =
RSSIPRX Register
internal RSSI
Data
Noise Run-In
Data
Reset
SPI
Figure 14 Peak Detector Behavior
Recommended Digital Trimming Procedure
• Download configuration file (Run Mode Slave; RSSISLOPE, RSSIOFFS set to
default, i.e. RSSISLOPE=1, RSSIOFFS=0)
• Turn off AGC (AGCSTART=0) and set gain to AGCGAIN=0
• Apply P_IN1 = -85 dBm RF input signal
• Read RSSIRX eleven times (minimum 10 ms in-between readings), use average of
last ten readings (always), store as RSSIM1
• Apply P_IN2 = -65 dBm RF input signal
• Read RSSIRX eleven times (minimum 10 ms in-between readings), use average of
last ten readings (always), store as RSSIM2
• Calculate measured RSSI slope SLOPEM=(RSSIM2-RSSIM1)/(P_IN2-P_IN1)
• Adjust RSSISLOPE for required RSSI slope SLOPER as follows:
RSSISLOPE=SLOPER/SLOPEM
• Adjust RSSIOFFS for required value RSSIR2 at P_IN2 as follows:
RSSIOFFS=(RSSIR2-RSSIM2)+(SLOPEM-SLOPER)*P_IN2
• The new values for RSSISLOPE and RSSIOFFS have to be added to the
configuration!
Data Sheet
35
V1.0, 2010-02-19