TDA7500A Datasheet, PDF (36/40 Pages) STMicroelectronics – DIGITAL AM/FM SIGNAL PROCESSOR

TDA7500A
Figure 20. lock Diagram of Car Amplifier Audio Sub-System.
ANALOG INPUT
FRONT END
TDA7421
I²C/SPI
TDA7501
AUDIO POWER
MAIN
MICRO
A/D
D/A
TDA7500A
EEPROM/
FLASH
SPDIF
DRAM/
SRAM
DIGITAL IN
DISPLAY
MICRO
DIGITAL OUT
Fig20TDA7500A
Clock Scheme
When TDA7500A is used in AD/FM mode the following scheme is choosen in order to avoid harmonics inside
the FM band. Parts of the system are directly clocked by the crystal oscillator, whereas other parts are driven
by the pll oscillator. Thanks to this it is possible to process any audio source as well analog as digital in parallel
to record FM mono for traffic informations, telephone resp. navigation and RDS. Figure 21 shows the clock
scheme. Regarding on the country and its FM bandwidth different crystals should be selected.
Figure 21. Clock Scheme
Fext: 44.1 kHz, 48kHz
OSC
Fcomp: 1.425 MHz (8.55/6)
1.411 MHz (44.1*2*16)
PLL 1.536 MHz (48*2*16)
Int./Ext.
Xtal
8.55 MHz
8.89 MHz
Stereo DSP
Audio DSP
Fvco:
173.85 MHz (Fcomp*122)
158.05 MHz (Fcomp*112)
172.03 MHz (Fcomp*112)
FM Japan
[MHz] 76..90
West Europe East
87.5..108 65..74
Fdsp:
43.46 MHz (Fvco/4)
39.51 MHz (Fvco/4)
43.01 MHz (Fvco/4)
2nd
90.38 86.92
Hamonics
3rd
135.57 130.38
Hamonics
86.92
90.38
130.38
135.57
A/D FM-rds /
noise det.
RDS-Demod.
Frds:
8.55 MHz (Fxtal)
A/D mono
level / tel. / navi.
A/D FM-mpx/
stereo audio
Faudio: 48.51 kHz
44.1 kHz
48 kHz
D/A Coverters
Fconverter:
12.42 MHz (Fvco/14)
11.29 MHz (Fvco/14)
12.29 MHz (Fvco/14)
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