TDA7411 datasheet(25/43 Pages) STMICROELECTRONICS

25 / 43 page

25/43

TDA7411

The gain can be programmed through 4 bits in the "Stereo Decoder Adjustment"-byte. The MONO-voltage

VMO (0dB channel separation) can be chosen selecting VSBL.

All necessary internal reference voltages like REF5V are derived from a bandgap circuit. Therefore they

have a temperature coefficient near zero. This is useful if the fieldstrength signal is also temperature com-

pensated. But most of the IF-devices are applying a LEVEL-voltage with a TC of 3300ppm. The A673 of-

fers this TC for the reference voltages, too. The TC is selectable with bit D7 of the "stereo decoder

adjustment"-byte.

Figure 20. Relation Between Internal and External LEVEL Voltages and Setup of Stereoblend

Highcut Control

The highcut control set-up is similar to the stereoblend control set-up: the starting point VHCH can be set

with 2 bits to be 42, 50, 58 or 66% of REF5V whereas the range can be set to be 17, 22, 28 or 33% of

VHCH (see fig. 21).

Figure 21. High cut characteristics

Functional Description of the Noise Blanker

In the automotive environment spikes produced by the ignition and for example the wiper-motor disturb

the MPX-signal. The aim of the noise blanker part is to cancel the audible influence of the spikes. There-

fore the output of the stereo decoder is held at the actual voltage for a time between 22 and 38µs (pro-

grammable). The block diagram of the noise blanker is given in fig.22

INTERNAL

VOLTAGES

modAU639

VSBL

REF 5V

SETUP OF VST

INTERNAL

VOLTAGES

29%

REF 5V

SETUP OF VMO

LEVEL

LEVEL INTERN

FIELDSTRENGHT VOLTAGE

VST

VMO

LEVEL INTERN

58%

VSBL

VST

VMO

FIELDSTRENGHT VOLTAGE

LOWPASS

TIME CONSTANT

D97AU640

τDeemp

FIELDSTRENGHT

VHCH

VHCL

•

τDeemp

TDA7411 Arkusz danych(PDF) 25 Page - STMicroelectronics

TDA7411 Arkusz danych(HTML) 25 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

Arkusz danych Pobierz

Link URL