TDA7439DS 查看數據表（PDF） - STMicroelectronics

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TDA7439DS

Three-band digitally-controlled audio processor

STMicroelectronics 

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3

Application suggestions

TDA7439DS

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 TDA7439DS audio processor provides 3 bands of tone control (bass, mid-range and

treble).

3.1

3.1.1

Tone control

Bass, mid-range stages

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

However, the bass cell has an internal resistor RB of typically 44 kΩ whilst the mid-range cell

has an internal resistor RM of typically 25 kΩ.

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

Ri internal

IN

OUT

C1

C2

R2

D95AU313

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

(R1 (internal) and R2, C1, C2 (external)) then the centre frequency fC, the gain Av at

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

fC

=

--------------------------------1--------------------------------

2 ⋅ π ⋅ R1 ⋅ R2 ⋅ C1 ⋅ C2

AV = R-----2----C--R---2--2--+-C----R-1----2-+---C--R--1--2---+-C----R-2----i-C-----1--

Q = -----R-R---1--2---C⋅---R--1---2--+---⋅--R-C---2-1---C--⋅---2C-----2--

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