CS4220 CS4221

DS284PP3

15

5.2.4

SOFT RAMP STEP RATE (RMP)

Default = 00

00 - 1 step per 8 LRCK’s

01 - 1 step per 4 LRCK’s

10 - 1 step per 16 LRCK’s

11 - 1 step per 32 LRCK’s

Function:

The rate of change for the Soft Ramp function is adjustable through the RMP bits.

5.3

Left Channel Output Attenuator Level (address 03h)

5.4

Right Channel Output Attenuator Level (address 04h)

5.4.1

ATTENUATION LEVEL (ATT7-ATT0)

Default = 00h

Function:

The Output Attenuator Level registers allow for attenuation of the DAC outputs in 0.5 dB increments

from 0 to 113.5 dB. Level changes are implemented with an analog volume control until the residual

output noise is equal to the noise floor in the mute state. At this point, volume changes are performed

digitally. This technique is superior to purely digital volume control because the noise is attenuated

by the same amount as the signal, thus preserving dynamic range, see Figure 16. Volume changes

are performed as dictated by the SOFT bit in the DAC Control register. ATT0 represents 0.5 dB of

attenuation and settings greater than 227 (decimal value) will mute the selected DAC output.

765

4321

0

ATT7

ATT6

ATT5

ATT4

ATT3

ATT2

ATT1

ATT0

000

0000

0

Binary Code

Decimal Value

Volume Setting

00000000

0

0 dB

11100011

227

-113.5 dB

11100100

228

Muted

Table 1. Example Volume Settings