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TDA7468

3

APPLICATION SUGGESTIONS

The first and the last stages are volume control blocks. The control range is 0 to -63dB (mute) with 1dB

step resolution for this first one, 0 to 24dB (mute) with 8dB step resolution for the last one.

The very high resolution allows the implementation of systems free from any noisy acoustical effect.

The TDA7468D audioprocessor provides 2 bands tones control.

3.1 Bass, Stages

Ω typical.

Several filter types can be implemented, connecting external components to the Bass IN and OUT pins.

The fig.5 refers to basic T Type Bandpass Filter starting from the filter component values (R1 internal and

R2,C1,C2 external) the centre frequency Fc, the gain Av at max. boost and the filter Q factor are computed

as follows:

3.2 Treble Stage

The treble stage is a high pass filter whose time constant is fixed by an internal resistor (25K

Ω typical) and

an external capacitor connected between treble pins and ground.

3.3 CREF

The suggested 10

µF reference capacitor (CREF) value can be reduced to 4.7µF if the application requires

faster power ON.

Figure 5.

F

C

1

2

π

R1 R2 C1 C2

⋅⋅

⋅

⋅⋅

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

=

A

V

R2 C2

R2 C1

Ri C1

+

+

R2 C1

R2 C2

+

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

=

Q

R1 R2 C1 C2

⋅⋅

⋅

R2 C1

R2 C2

+

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

=

C1

A

V

1

–

2

π F

Q

⋅⋅

⋅

⋅

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

C2

Q

2

C1

⋅

A

V

1

–

Q

2

–

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

==

R2

A

V

1

–

Q

2

–

2

π C1 F

C

A

V

1

–

() Q

⋅⋅

⋅

⋅⋅

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

=

Ri internal

OUT

IN

D95AU313