TDA7386_07 Datasheet, PDF (11/14 Pages) STMicroelectronics – 4 x 45W quad bridge car radio amplifier

TDA7386
3
Application hints
Application hints
Referred to the circuit of Figure 3.
3.1
SVR
Besides its contribution to the ripple rejection, the SVR capacitor governs the turn ON/OFF
time sequence and, consequently, plays an essential role in the pop optimization during
ON/OFF transients.
To conveniently serve both needs, ITS MINIMUM RECOMMENDED VALUE IS 10μF.
3.2
Input stage
The TDA7386’s inputs are ground-compatible and can stand very high input signals (±8Vpk)
without any performances degradation.
If the standard value for the input capacitors (0.1μF) is adopted, the low frequency cut-off
will amount to 16 Hz.
3.3
Stand-by and muting
Stand-by and muting facilities are both CMOS-compatible. If unused, a straight connection
to Vs of their respective pins would be admissible.
Conventional/low-power transistors can be employed to drive muting and stand-by pins in
absence of true CMOS ports or microprocessors. R-C cells have always to be used in order
to smooth down the transitions for preventing any audible transient noises.
Since a DC current of about 10 μA normally flows out of pin 22, the maximum allowable
muting-series resistance (R₂) is 70KΩ, which is sufficiently high to permit a muting capacitor
reasonably small (about 1μF).
If R₂ is higher than recommended, the involved risk will be that the voltage at pin 22 may rise
to above the 1.5 V threshold voltage and the device will consequently fail to turn OFF when
the mute line is brought down.
About the stand-by, the time constant to be assigned in order to obtain a virtually pop-free
transition has to be slower than 2.5V/ms.
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