TAS5036IPFCR datasheet(22/49 Pages) TI

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Architecture Overview

SLES044B—November 2002

TAS5036

2.3

Signal Processing

This section contains the signal processing functions that are contained in the TAS5036. The signal

processing is performed using a high-speed 24-bit signal processing architecture. The TAS5036 performs the

following signal processing features:

•

Individual channel soft volume with a range of 24 dB to –114 dB plus mute

•

Soft mute

•

Auto mute

•

50-

µs/15-µs de-emphasis filter supported in the sampling rates 32 kHz, 44.1 kHz, and 48 kHz

2.3.1 Volume Control

The gain of each output can be adjusted by a soft digital volume control for each channel. Volume adjustments

are performed using a soft gain update s-curve, which is approximated using a second order filter fit. The curve

fit is performed over a transition interval between 41 ms and 65 ms.

The volume of each channel can be adjusted from mute to 24 dB to –114 dB in 0.5 dB steps. Because of the

numerical representation that is used to control the volume, at very low volume levels the step size increases

for gains of that are less than –96 dB. The default volume setting following power up or reset is 0 dB for all

channels. The step size increases linearly up to approximately –90 dB, see Figure 2–10.

Attenuation (Gain) – dB

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

–110

–100

–90

–80

–70

–60

–50

–40

–30

–20

–10

STEP SIZE

ATTENUATION (GAIN)

Figure 2–10. Attenuation Curve

The volume control format for each channel is expressed in 8 bits. The volume for each channel is set by writing

8 bits via the serial control interface. The MSB bit is written first as in the bit position 0 (LSB position).

The volume for each channel can be set using a single or multiple address write operation to the volume control

updated.

To coordinate the volume adjustment of multiple channels simultaneously, the TAS5036 performs a delayed

volume update upon receiving a volume change command. Following the completion of the register volume

write operations, the TAS5036 waits for 5 ms for another volume command to be given. If no volume command

is issued in that period of time, the TAS5036 starts adjusting the volume of the channels that received volume

settings.

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