TDA7419 Datasheet, PDF (17/30 Pages) STMicroelectronics – 3 BAND CAR AUDIO PROCESSOR

TDA7419
5.10 Spectrum Analyzer
A fully integrated seven-band spectrum analyzer with programmable quality factor is present. The spec-
trum analyzer consists of seven band pass filters with rectifier and sample capacitor that stores the max-
imum peak signal level since the last read cycle. This peak signal level can be read by a microprocessor
at the SAout-pin. To allow easy interfacing to an analog port of the microprocessor, the output voltage at
this pin is referred to device ground.
The microprocessor starts a read cycle with the negative going clock edge at the SAclk input. On the fol-
lowing positive clock edges, the peak signal level for the band pass filters is subsequently switched to
SAout. Each analog output data is valid after the time t_Sadel. A reset of the sample capacitors is induced
whenever SAclk remains high for the time t_intres. Note that a proper reset requires the clock signal SAclk
to be held at high potential. Figure 20 shows the block diagram and figure 21 illustrates the read cycle
timing of the spectrum analyzer.
Figure 20. Spectrum analyzer block diagram
Figure 21. Timing of the spectrum analyzer
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