Application suggestions

TDA7439

8/23

3

Application suggestions

The first and the last stages are volume control blocks. The control range is 0 to -47 dB and

mute for the first stage and 0 to -79 dB and mute for the last one. Both control blocks have a

step resolution of 1 dB.

This very high resolution allows the implementation of systems free from any noisy

acoustical effect.

The TDA7439 audio processor provides 3 bands of tone control (bass, mid-range and

treble).

3.1

Tone control

3.1.1

Bass, mid-range stages

The bass and the mid-range cells have the same structure.

Several filter types can be implemented by connecting external components to the bass/mid

IN and OUT pins.

Typical responses are shown in Figure 8, Figure 9 and Figure 11.

Figure 4.

Bass/mid-range filter implementation

Figure 4. refers to the basic T-type band-pass filter. Starting from the filter component values

maximum boost and the filter Q factor are computed as follows:

Ri internal

OUT

IN

D95AU313

f

C

1

2

π

R1 R2 C1 C2

⋅⋅

⋅

⋅⋅

-----------------------------------------------------------------

=

A

V

R2C2

R2C1

RiC1

++

R2C1

R2C2

+

------------------------------------------------------------

=

Q

R1 R2 C1 C2

⋅⋅

⋅

R2C1

R2C2

+

-------------------------------------------------

=