AD1985 Analog Devices, AD1985 Datasheet - Page 40

• Manufacturer Part Number: AD1985
• Description: AC'97 2.3 Soundmax Codec W/jack Sensing
• Manufacturer: Analog Devices

AD1985
DMIX[1:0]
HPSEL
CLDIS
LODIS
MSPLT
AC97NC
DACZ
Down-Mix Mode Select. Provides analog down-mixing of the Center, LFE, and/or Surround channels into the Mixer
channels. This allows the full content of 5.1 or quad media to be played through stereo headphones or speakers.
Note that the Jack Sense pins can also be set up to control (gate) this function depending on the JS0DMX and JS1DMX bits
(see Register 0x72).
The upper bit allows forcing the Down-Mix function:
DMIX[1] = 0: No Down-Mix unless activated by the Jack Senses and JSxDMX bits. (Default.)
DMIX[1] = 1: Forces Down-Mix function.
The lower bit selects the Down-Mix type:
DMIX[0] = 0: Selects 6-to-4 Down-Mix. The Center and LFE channels are summed equally into the Mixer L/R
DMIX[0] = 1: Selects 6-to-2 Down-Mix. The Surround L/R channels are summed into the Mixer L/R channels. The Center and
Default for DMIX[1:0] is 00.
Headphone amplifier Input Select. This bit allows the headphone power amps to be driven from the Surround DACs or
from the Mixer outputs. There are two reasons for this, one is to allow 2-channel media to use the higher power
headphone amplifiers available on the SURR/HP_OUT outputs, the other is to allow spreading of 2-channel media to the
Surround outputs.
Together with the LOSEL bit (see above), this bit also provides for analog swapping of the Mixer (Front) and Surround
outputs.
0: SURR_out/HP_OUT outputs are driven by the Surround DACs. (Reset default.)
1: SURR_out/HP_OUT outputs are driven by the Mixer outputs.
Center and LFE Disable: Disables the Center and LFE output pins, placing them into High-Z mode so that the assigned
output audio jacks can be shared for MIC inputs or other functions.
0: Center and LFE output pins have normal audio drive capability. (Reset default.)
1: Center and LFE output pins are placed into High-Z mode.
LINE_OUT Disable: Disables the LINE_OUT pins (L/R), placing them into High-Z mode so that the assigned output audio
jack can be shared for Line Input function.
0: LINE_OUT pins have normal audio drive capability. (Reset default.)
1: LINE_OUT pins are placed into High-Z mode.
Mute Split. Allows separate mute control bits for left and right channels in Master, HP, LINE_IN, CD, PCM OUT, and Record
volume/gain control registers.
0: Both left and right channel mutes are controlled by Bit D15 in their respective registers. (Reset default.)
1: Bit D15 affects only the left channel mute and Bit D7 affects only the right channel mute.
AC ’97 No Compatibility Mode. Changing this bit allows the Surround, Center, and LFE volume control registers and
output attenuators to operate in a more functional mode than what’s defined by the AC ’97 spec. This is called ADI
compatibility mode.
In AC ’97 compatibility mode the DAC gain/attenuators for the Surround, Center, and LFE are controlled by Register 0x18
(PCM volume). The output pin attenuators for the Surround are controlled by Register 0x38 and the output pin
attenuators for the Center and LFE are controlled by Register 0x36.
In ADI compatibility mode the Surround DAC Gain/Attenuators are controlled by Register 0x38 and the Center/LFE DAC
Gain/Attenuators are controlled by Register 0x36. The output pin attenuators for the Surround, Center, and LFE are
controlled by Register 0x02 (Master Volume).
0: AC ’97 compatibility mode. (Reset default.)
1: ADI compatibility mode.
DAC Zero-Fill. Determines DAC data fill under starved condition.
0: DAC data is repeated when DACs are starved for data. (Reset default.)
1: DAC data is zero-filled when DACs are starved for data.
channels. (Default.)
LFE are summed equally into the Mixer left and right channels.
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