STA323W datasheet(42/71 Pages) STMICROELECTRONICS

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STA323W

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Post-scale functionality is an attenuation placed after the volume control and directly before

the conversion to PWM. Post-scale can also be used to limit the maximum modulation index

and therefore the peak current. Setting 1, in the PSL register, causes the value stored in

Channel 1 post-scale to be used for all three internal channels.

7.5.5

Biquad coefficient link

For ease of use, all channels can use the biquad coefficients loaded into the channel 1

coefficient RAM space by setting the BQL bit to 1. Therefore, any EQ updates only have to

be performed once.

7.5.6

Dynamic range compression/anti-clipping bit

Both limiters can be used in one of two ways: anti-clipping or dynamic range compression.

When used in anti-clipping mode the limiter threshold values are constant and dependent on

the limiter settings. In dynamic range compression mode the limiter threshold values vary

with the volume settings allowing a nighttime listening mode that provides a reduction in the

dynamic range regardless of the volume level.

7.5.7

Zero-detect mute enable

Setting the ZDE bit enables the zero-detect automatic mute. When ZDE=1, the zero-detect

circuit looks at the input data to each processing channel after the channel-mapping block. If

any channel receives 2048 consecutive zero value samples (regardless of fs) then that

individual channel is muted if this function is enabled.

Table 33.

Biquad coefficient link

Bit

R/W

RST

Name

Description

4R/W

BQL

0: each channel uses coefficient values

1: each channel uses channel 1 coefficient values

Table 34.

Dynamic range compression/anti-clipping bit

Bit

R/W

RST

Name

Description

5R/W

DRC

0: limiters act in anti-clipping mode

1: limiters act in dynamic range compression mode

Table 35.

Zero-detect mute enable

Bit

R/W

RST

Name

Description

R/W

ZDE

Setting of 1 enables the automatic zero-detect mute

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