TDA7374B
WHAT IS NEEDED FOR A DEMONSTRATION
- a XT or AT IBM compatible PC, supplied with
EGA card
- a SGS-THOMSON audioprocessor application disk
- a TDA 7302 + TDA7374B board
- a connector from audioprocessor board to PC
parallel port
CLIPPING DETECTOR
Fig 19 shows an application using the TDA7374B
in combination with the SGS-THOMSON audio-
processor TDA7302.
The output clipping is recognizedby the microproc-
essor (in this application it is simulated by a PC).
The detailed way to operate of the system is rep-
resented by the flow-chart of fig.18.
GENERAL INFORMATION
The controller detects when the clipping is active
(minimun detection width fixed by a C29 = 12 nF
external capacitor), and reduces the volume (or
bass ) by step of 2 dB (with a programmable wait-
ing time), until no more clipping is detected.
Then the controller waits for a programmable time
before increasing the volume again by step of 2
dB until clipping is again detected or the panel se-
lected volume is reached.
Practical advantages of this application is a better
sound quality deriving from operation under no
clipping conditions, which also means the avail-
ability of higher undistorted power.
In the application shown in fig 18 the TDA7302
audioprocessor works on PC XT or AT IBM com-
patible.
Control is accomplished by serial bus ( S-bus or
I2C-bus or SPI bus) sent to the test board through
the PC parallel port.
The PC simulates the behaviour of the microproc-
essor in a real application (for example in a car
radio) and the buffer is necessary only in this ap-
plication for protectingthe PC.
Figure: 18: Clipping Detector Control Routine
10/13
STMICROELECTRONICS [ ST ]
