TDA7415CB Datasheet, PDF (29/50 Pages) STMicroelectronics – Car radio multimedia signal processor

TDA7415CB
Description of the audio processor
six soft-mute pins low (hardware-mute) or by assessing the corresponding programming bits
(software-mute).
For the In-section, a soft-mute is always stereo for each of the three signal-paths and the
bus-triggered mute exactly corresponds to the pin-triggered mute, with the exception that
the later is inherently faster in response. This behavior is also true for the Out-section, but
here the bus-triggered mute is independent for all six single L/R-channels.
All mute-pins have internal pull-ups connected to a 3,3Volts reference that allow the
connection to either a 3,3V- or a 5V-microproccessor. Reverse flowing currents are limited to
100µA, so that the mute-pins may be driven by both, open-drain or push-pull outputs.
The envelope slope of the soft-mute was realized in a special S-shaped curve to soften the
mute transitions in the critical regions (see Figure 20). The completion time for full mute / no
mute is programmable by I²C/SPI-bus in four different values.
Figure 20. Soft-mute signal envelope versus time
Note:
5.4
A triggered mute is always completed and cannot be interrupted by a change of the initial
mute condition.
For the programming of the soft-mute, see the programming chapter.
Spectrum analyzer
A fully integrated seven-band spectrum analyzer is present in the TDA7415CB (Figure 21).
The spectrum analyzer consists of seven band pass filters followed by rectifiers with sample
capacitors that store the maximum peak signal level for each band 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 input-port of a microprocessor, the output voltage at this pin is
referred to device ground. Since the output voltage follows the peak level linearly, the
microprocessor should take care for a logarithmic conversion (e.g. logarithmic look-up
table).
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