TDA7540N Datasheet, PDF (66/76 Pages) STMicroelectronics – AM/FM car radio tuner IC with stereo decoder and intelligent selectivity system (ISS)

Appendix
TDA7540N
Block diagram quality detection principle (without overdeviation correction)
Table 52. Block diagram quality detection principle
Signal
Low
High
ac
No adjacent channel
Adjacent channel present
ac+
No strong adjacent channel
Adjacent channel higher as ac
sm
Fieldstrength higher as softmute threshold Fieldstrength lower as softmute threshold
dev
Deviation lower as threshold DWTH
Deviation higher as threshold DWTH
dev+
Deviation lower as threshold DTH*DWTH Deviation higher as threshold DTH*DWTH
inton
ISS filter off by logic (wide)
ISS filter on by logic
int80
ISS filter 120kHz (mid)
ISS filter 80kHz (narrow)
Table 53. Functional mode quality detection
Input signals
ac
ac+
sm
dev dev+ inton
0
0
0
0
0
0
0
0
0
1
0
0
0
0
0
1
1
0
0
0
1
0
0
1
0
0
1
1
0
0
0
0
1
1
1
0
1
0
0
0
0
1
1
1
0
0
0
1
1
0
0
1
0
1
1
1
0
1
1
1
1
0
1
0
0
1
1
1
1
0
0
1
1
0
1
1
0
1
1
1
1
1
0
1
1
0
1
1
1
1
1
1
1
1
1
1
Mode1
int80
0
0
0
1
0
0
1
1
0
0
1
1
0
0
0
0
Function
wide
wide
wide
narrow
wide
wide
narrow
narrow
mid
mid
narrow
narrow
mid
mid
mid
mid
inton
0
0
0
1
1
0
1
1
1
1
1
1
1
1
1
1
Mode2
int80
0
0
0
1
0
0
0
1
0
1
1
1
0
1
0
1
Function
wide
wide
wide
narrow
mid
wide
mid
narrow
mid
narrow
narrow
narrow
mid
narrow
mid
narrow
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