Application information

TDA7491HV

22/26

7.6

Output low-pass filter

To avoid EMI problems, it may be necessary to use a low-pass filter before the speaker. The

cutoff frequency should be larger than 22 kHz and much lower than the output switching

frequency. It is necessary to choose the L-C component values depending on the loud

speaker impedance. Some typical values, which give a cut-off frequency of 27 kHz, are

shown in Figure 28 and Figure 29 below.

Figure 28.

Typical LC filter for a 8-

Ω speaker

Figure 29.

Typical LC filter for a 4-

Ω speaker