Changhong Electric 21NF55, Service Manual, Page: 32 / 83

SERVICE MANUAL
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1.6 Audio effect processor TDA7449
TDA7449 TONE CONTROLDIGITALLY CONTROLLED
AUDIO PROCESSORINPUT MULTIPLEXER
1) Features
- 2 stereo inputs
- selectableinput gain for optimal Adaptationto different
sources One stereo output Treble, and bass control in 2.0db
Steps Volumecontrol in 1.0db steps Two speaker attenuators:
- two independentspeakercontrol In 1.0dbsteps for
balancefacility
- independent mute function All function are programmable via
Serial bus
2) descripion
The tda7449 is a volume tone (bass and treble) Balance
(left/right) processor for quality audio Applications in TV
systems.
Selectable input gain is provided. Control of all the functions is accomplished by serial bus.
The ac signal setting is obtained by resistor networks and switches combined with operational
Amplifiers.
Thanks to the used bipolar/cmostechnology, Low distortion, low noise and dc stepping are Obtained.
3) Block Diagram
Fig.18