TDA7389

Application hints

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3

Application hints

Ref. to the circuit of Figure 14.

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 22µF, 47µF

can be used to optimize pop performances.

3.2

Input stage

The TDA7389’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.

The input capacitors should be 1/4 of the capacitor connected to AC-GND pin for optimum

pop performances.

3.3

Stand-by and Muting

Stand-by and Muting facilities are both 3.3V CMOS-COMPATIBLE. If unused, a straight

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 10µA normally flows out of pin 23, the maximum allowable

reasonably small (about 1µF).

to above the 1.2V 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.