CS42448 datasheet(31/70 Pages) CIRRUS

31 / 70 page

DS648PP2

4.3.6 Digital Volume Control

Each DAC’s output level is controlled via the Volume Control registers operating over the range

of 0 to -127.5 dB attenuation with 0.5 dB resolution. See “AOUTX Volume Control (addresses

08h- 0Fh)” on page 52. Volume control changes are programmable to ramp in increments of

0.125 dB at the rate controlled by the SZC[1:0] bits in the Digital Volume Control register. See

“Transition Control (address 06h)” on page 50.

Each output can be independently muted via mute control bits in the register “DAC Channel

Mute (address 07h)” on page 52. When enabled, each AOUTx_MUTE bit attenuates the corre-

sponding DAC to its maximum value (-127.5 dB). When the AOUTx_MUTE bit is disabled, the

corresponding DAC returns to the attenuation level set in the Volume Control register. The at-

tenuation is ramped up and down at the rate specified by the SZC[1:0] bits.

4.3.7 De-Emphasis Filter

The CS42448 includes on-chip digital de-emphasis optimized for a sample rate of 44.1 kHz. The

filter response is shown in Figure 14. The de-emphasis feature is included to accommodate au-

dio recordings that utilize 50/15

µs pre-emphasis equalization as a means of noise reduction.

De-emphasis is only available in Single Speed Mode. Please see “DAC De-Emphasis Control

(DAC_DEM)” on page 49 for de-emphasis control.

AOUTx+

AOUTx-

Full-Scale Differential Output Level =

(AOUTx+) - (AOUTx-) = 6.5 VPP = 2.3 VRMS

4.125 V

2.5 V

0.875 V

5.0 V

4.125 V

2.5 V

0.875 V

Figure 13. Full-Scale Output

Gain

-10dB

0dB

Frequency

T2 = 15 µs

T1=50 µs

3.183 kHz

10.61 kHz

Figure 14. De-Emphasis Curve

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