TDA5235
Functional Description
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 PIN1 = -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 PIN2 = -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)/(PIN2-PIN1)
• Adjust RSSISLOPE for required RSSI slope SLOPER as follows:
RSSISLOPE=SLOPER/SLOPEM
• Adjust RSSIOFFS for required value RSSIR2 at PIN2 as follows:
RSSIOFFS=(RSSIR2-RSSIM2)+(SLOPEM-SLOPER)*PIN2
• The new values for RSSISLOPE and RSSIOFFS have to be added to the
configuration!
Notes:
1. The upper RF input level must stay well below the saturation level of the receiver (see
Chapter 2.4.6.4 Digital Automatic Gain Control Unit (AGC))
2. The lower RF input level must stay well above the noise level of the receiver
3. If IF Attenuation is trimmed, this has to be done before trimming of RSSI
4. If RSSI needs to be trimmed in a higher input power range the AGCGAIN must be set
accordingly
Data Sheet
37
V1.0, 2010-02-19
INFINEON [ Infineon ]
