DS1113F1
23
CS4399
4.2 Analog Outputs
4.2 Analog Outputs
The CS4399 provides an analog output that is derived from the digital audio input ports. This section describes the general
flow of the analog outputs.
4.2.1
Analog Output Signal Flow
The CS4399 signal flow is shown in
Figure 4-1. Analog Output Signal Flow
The CS4399 has 2 settings of full scale voltage, which are determined by OUT_FS[1:0]. The proper full scale voltage must
be set first, and the digital volume settings is used to control signal levels.
The CS4399 digital volume control allows independent control of the signal level in 1/2 dB increments from 0 dB
(0b0000 0000) to –127 dB (0b1111 1110) by using x_VOLUME_y (where "x" is either PCM or DSD; "y" is either A or B)
register. When the x_VOL_BEQA bit is set, both volumes can be changed simultaneously using x_VOLUME_A). The
volume changes are implemented as dictated by PCM_SZC[1:0] and DSD_SZC in the signal control register (see
). If soft ramping is enabled, gain and attenuation changes are carried out by incrementally
changing the volume level in 1/8-dB steps, from the previous level to the new level. For PCM, when PCM_SZC[1:0] = 2,
the volume level changes at an approximate rate of 1 dB/ms. For DSD, when DSD_SZC = 1, the volume level also
changes at an approximate rate of 1 dB/ms during power up or when coming out of a mute state (DSD_MUTE_x = 1). Note
that when recovering from an error state caused by static DSD data (DSD_STUCK_INT = 1), the volume output will
resume at the level specified in DSD_VOLUME_x registers. Both channels can be inverted by setting the INV_A and INV_
B bits.
The CS4399 provides individual ramp-up control option (from the global soft ramp settings) for a specific scenario. The
PCM_RAMP_DOWN bit is for the scenario when the interpolation filter switches during PCM playback. Refer to the
register description for setting details.
The CS4399 can mute both channels simultaneously or independently. Also, it can auto-mute on both PCM stream and
DSD stream when mute pattern is identified (defined in PCM_AMUTE and DSD_AMUTE). Additional signal and mute
control options can be found in
and
The CS4399 has an independent set of controls for the DSD processor path as shown in
. The DSD processor
also offers the control bit SIGCTL_DSDEQPCM, which maps the PCM_x setting to DSD_x setting, once enabled. As a
result, some of the DSD_x register settings are ignored. The registers affected are DSD_VOL_BEQA, DSD_SZC, DSD_
AMUTE, DSD_AMUTE_BEQA, DSD_MUTE_A, DSD_MUTE_B, DSD_INV_A, DSD_INV_B, DSD_SWAP_CHAN, and
Multibit
Modulator
Multibit
Modulator
Interpolation
Filter &
Volume
Control
Interpolation
Filter &
Volume
Control
AOUTA
AOUTB
DSD
Processor
DoP to
DSD
Engine
MU
X
Audio
Source
I
2
S
REFB
REFA
DoP
DSD
DAC and
Filter
DAC and
Filter