TDA7439

6/19

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:

Viceversa, once Fc, Av, and Ri internal value are fixed, the external components values will be:

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 Typical responses are reported in Figg.

10 to 13.

3.3 CREF

The suggested 10

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

faster power ON.

F

C

1

2

π

R1 R2 C 1 C2

⋅⋅

⋅

⋅⋅

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

=

A

V

R2C 2

R2C1

RiC1

++

R2 C1

R2C2

+

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

=

Q

R 1 R2 C1 C2

⋅⋅

⋅

R 2C1

R2C2

+

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

=

C1

A

V

1

–

2

π Fc Ri Q

⋅⋅

⋅

⋅

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

C2

Q

2

C1

⋅

A

V

1

–

Q

2

–

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

=

=

R2

A

V

1

–

Q

2

–

2

π C1 Fc A

V

1

–

() Q

⋅⋅

⋅⋅

⋅

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

=

Figure 6. THD vs. frequency

Figure 7. THD vs. RLOAD