TDA7416 Datasheet, PDF (15/27 Pages) STMicroelectronics – CARRADIO SIGNAL PROCESSOR

TDA7416
1.8 Spectrum analyzer
A fully integrated seven band spectrum analyzer with programmable quality factor is present in the
TDA7416(Fig. 13).
The spectrum analyzer consists of seven band pass filters with rectifier and sample capacitor which stores
the maximum peak signal level since the last read cycle. This peak signal level can be read by a micro-
processor at the SAout-pin. To allow easy interfacing to an analog port of the microprocessor, the output
voltage at this pin is re-ferred 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 13 shows the block diagram and figure 14 illustrates the read cycle
timing of the spectrum analyzer.
Figure 13. Spectrum analyzer block diagram
Figure 14. Timing spectrum analyzer
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