Datasheet
MODE CONTROL REGISTERS
User-Programmable Mode Controls
PCM1795
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........................................................................................................................................................................................................ SLES248 – MAY 2009
The PCM1795 includes a number of user-programmable functions that are accessed via mode control registers.
The registers are programmed using the serial control interface, as previously discussed in the SPI Interface and
I
2
C Interface sections. Table 8 lists the available mode-control functions, along with the default reset conditions
and associated register index.
Table 8. User-Programmable Function Controls
DF
FUNCTION DEFAULT REGISTER BIT PCM DSD BYPASS
Digital attenuation control Register 16 ATL[7:0] (for left channel)
0 dB Yes No No
0 dB to – 120 dB and mute, 0.5-dB step Register 17 ATR[7:0] (for right channel)
Attenuation load control
Attenuation disabled Register 18 ATLD Yes No No
Disabled, enabled
Input audio data format selection
16-, 20-, 32-bit standard (right-justified)
Register 18 FMT[2:0] Yes No Yes
24-bit I
2
S format
format
24-bit MSB-first left-justified format
16-/32-bit I
2
S format
Sampling rate selection for de-emphasis
De-emphasis disabled Register 18 DMF[1:0] Yes Yes
(1)
No
Disabled, 44.1 kHz, 48 kHz, 32 kHz
De-emphasis control
De-emphasis disabled Register 18 DME Yes No No
Disabled, enabled
Soft mute control
Mute disabled Register 18 MUTE Yes No No
Soft mute disabled, enabled
Output phase reversal
Normal Register 19 REV Yes Yes Yes
Normal, reverse
Attenuation speed selection
× 1 f
S
Register 19 ATS[1:0] Yes No No
× 1f
S
, × (1/2)f
S
, × (1/4)f
S
, × (1/8)f
S
DAC operation control
DAC operation enabled Register 19 OPE Yes Yes Yes
Enabled, disabled
Stereo DF bypass mode select
Monaural Register 19 DFMS Yes No Yes
Monaural, stereo
Digital filter roll-off selection
Sharp roll-off Register 19 FLT Yes No No
Sharp roll-off, slow roll-off
Infinite zero mute control
Disabled Register 19 INZD Yes No Yes
Disabled, enabled
System reset control
Normal operation Register 20 SRST Yes Yes Yes
Reset operation, normal operation
DSD interface mode control
Disabled Register 20 DSD Yes Yes No
DSD enabled, disabled
Digital-filter bypass control
DF enabled Register 20 DFTH Yes No Yes
DF enabled, DF bypass
Monaural mode selection
Stereo Register 20 MONO Yes Yes Yes
Stereo, monaural
Channel selection for monaural mode data
Left channel Register 20 CHSL Yes Yes Yes
Left channel, Right channel
Δ Σ oversampling rate selection
× 64 f
S
Register 20 OS[1:0] Yes Yes
(2)
Yes
× 64 f
S
, × 128 f
S
, × 32 f
S
PCM zero output enable Enabled Register 21 PCMZ Yes No Yes
DSD zero output enable Disabled Register 21 DZ[1:0] Yes Yes No
(1) When in DSD mode, DMF[1:0] is defined as DSD filter (analog FIR) performance selection.
(2) When in DSD mode, OS[1:0] is defined as DSD filter (analog FIR) operating rate selection.
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