TAS3002 datasheet(30/74 Pages) TI

30 / 74 page

4–6

4.10 Dynamic Range Compression/Expansion (DRCE)

The TAS3002 device provides the user with the ability to manage the dynamic range of the audio system. The DRCE

receives data, and affects scaling after the volume/loudness block. As shown in Figure 4–4, the DRCE is applied after

the volume/loudness control block as a DRCE scale factor. The DRCE must be adjusted such that the signal does

not reach the hard limit value. However, if the signal does reach the maximum digital value, the saturation logic serves

as a hard limiter that does not allow the signal to extend beyond the available range.

SDIN2_L

(7)

2nd Order

IIR Filters

Bass/

Treble

Soft

Volume/

LEFT_OUT

Loudness

(Parametric

Equalization)

(Tone)

LEFT_SUM

SDIN1_L

(Left Channel Mixer)

ANALOGIN_L

(DRCE Scaling)

Saturation

Logic

Dynamic

Range

Control

(Analog in From ADC)

SDIN2_R

(7)

2nd Order

IIR Filters

Bass/

Treble

Soft

Volume/

RIGHT_OUT

Loudness

(Parametric

Equalization)

(Tone)

RIGHT_SUM

SDIN1_R

(Right Channel Mixer)

ANALOGIN_R

(DRCE Scaling)

Saturation

Logic

Figure 4–4. TAS3002 Digital Signal Processing Block Diagram

The DRCE instruction consists of eight bytes that must be sent each time in the order shown in the example code

of Table A–9. Each instruction downloaded must be eight bytes. If only one byte is changed, all eight bytes must be

transmitted. The first two bytes remain the same for every instruction, however the last six bytes can be programmed

using hexadecimal values from the corresponding tables referred to in Section A.8.

With high compression ratios and fast attack times available, this function is suited for a commercial killer in a

television set application.

4.11 AllPass Function

This function is enabled by setting terminal 27 (ALLPASS) on the TAS3002 device to 1. When asserted, the internal

equalization filters are set into AllPass (flat) mode. When this terminal is reset to 0, the equalization filters are returned

to the equalization that was in use before the terminal was asserted.

In AllPass mode, the bass and treble controls are still functional.

This function is frequently used for headphones. When the headphone plug is inserted into its jack, a switched contact

in the jack enables the AllPass function.

The AllPass function also can be activated by writing a 1 to bit 2 of the analog control register.

TAS3002 Datasheet(PDF) 30 Page - Texas Instruments

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