AD1985 Analog Devices, AD1985 Datasheet - Page 39

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

Miscellaneous Control Bits (Index 0x76)
Reg
Num
0x76 Misc
MBG[1:0]
VREFD VREFH
SRU
LOSEL
2CMIC
SPRD
Name
Control Bits
MIC Boost Gain Select Register. These two bits allow changing both MIC preamp gain blocks from the nominal +20 dB gain
boost. Both MIC1 and MIC2 preamps will be set to the same selected gain.
Note: This gain setting only takes effect while Bit D6 (M20) on the MIC Volume Register (0x0E) is set to 1, otherwise the MIC
boost blocks have a gain of 0 dB.
00: +20 dB gain. (Reset default.)
01: +10 dB gain.
10: +30 dB gain.
11: Reserved.
Controls the level of V
VREFH
Sample Rate Unlock. Controls all DAC sample rate locking.
0: All DAC sample rates are locked to the Front sample rate. (Reset default.)
1: DAC sample rates can be set independently for Front, Surround, and LFE.
LINE_OUT Amplifiers Input Select. This bit allows the LINE_OUT output amplifiers to be driven by the Mixer or the
Surround DACs. The main purpose for this is to allow swapping of the Front and Surround channels to make better use of
the SURR/HP_OUT output amplifiers. This bit should normally be used in tandem with the HPSEL bit (see below).
0: LINE_OUT amplifiers are driven by the MIXER outputs. (Reset default.)
1: LINE_OUT amplifiers are driven by the SURROUND DAC outputs.
2-Channel MIC Select. This bit enables simultaneous recording from MIC1 and MIC2 inputs, using a stereo microphone
array. Note that this register works in conjunction with the MS and OMS bits.
0: MIC1 or MIC2 (determined by MS bit) is routed to the Mixer/Record Selector’s left and right MIC channels. (Reset
1: MIC1 is routed to the Mixer/Record Selector’s left MIC Channel, and MIC2 is routed to the Mixer/Record Selector’s right
The OMS bit will select from the MIC1/2 or CENTER/LFE pins as the input source for the microphone. See the Record
Selector (Reg. 0x1A), MS bit (Bit D8 Reg. 0x20) or OMS bit (Bit D9 Reg. 0x74) definitions for more information.
SPREAD Enable. This bit enables spreading of 2-channel media to all six output channels. This function is implemented in
the analog section by using the output selector control lines for the Center/LFE, Surround, and LINE_OUT output channels.
Note that the Jack Sense pins can also be set up to control (gate) this function depending on the JSSPRD bit (see
Register 0x72).
0: No Spreading occurs, unless activated by the Jack Senses and JSSPRD bit. (Reset default.)
1: The SPRD selector drives the Center and LFE outputs from the MONO_OUT, the HPSEL selector drives the SURR/HP_OUT
Note that the SPRD bit overrides the current output selector control lines, set up by bits LOSEL and HPSEL as follows:
LOSEL = 0 and HPSEL = 1.
D15 D14
DACZ AC97NC MSPLT LODIS CLDIS HPSEL DMIX1 DMIX0 SPRD 2CMIC LOSEL SRU VREFH VREFD MBG1 MBG0 0x0000
default.)
outputs from the Mixer outputs and the LOSEL selector drives the LINE_OUT outputs also from the Mixer outputs.
0
0
1
1
MIC channel. The MS bit will swap the MIC1/2 left and right assignments.
VREFD
0
1
0
1
D13
REFOUT
2.25 V (default)
High Z
3.7 V
0 V
D12
pin as follows:
D11 D10
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D9
D8
D7
D6
D5
D4 D3
D2
D1
D0
AD1985
Default