Applications information

TDA7493

16/30

Doc ID 14570 Rev 6

5.6

Output low-pass filter

To avoid EMI problems, a low-pass filter can be inserted before the speaker. The cut-off

frequency of the filter should be higher than 22 kHz and much lower than the switching

frequency.

The component values of the filter vary according to the speaker impedance.

A typical LC output filter for a speaker impedance of 8

Ω and with a cut-off frequency of

27 kHz is shown in Figure 9.

Figure 9.

Typical LC filter for 8

Ω speaker

A similar filter for a speaker impedance of 4

Ω and also with a cut-off frequency of 27 kHz is

shown in Figure 10:

Figure 10.

Typical LC filter for 4

Ω speaker

33 µH

8

Ω

0.47 µF

0.10 µF

0.10 µF

330 pF

20

Ω

33 µH

OUTP

OUTN

0.47 µF

15 µH

OUTP

OUTN

330 pF

20

Ω

15 µH

0.22 µF

0.22 µF

4

Ω