REV. 0

AD1980

–27–

MBG[1:0]

MIC Boost Gain Select Register.

These two bits allow changing the MIC preamp gain from the nominal 20 dB gain. Both MIC1/MIC2 and MIC2

preamps will be set to the same selected gain.

Note that this gain takes effect only while Bit D6 (M20) on the MIC volume register (0Eh) is set to 1; otherwise the

MIC boost block has a gain of 0 dB.

00 = 20 dB gain (reset default)

01 = 10 dB gain

10 = 30 dB gain

11 = reserved

VREFD

Note that this bit overrides the VREFH bit selection (see below).

VREFH

SRU

Sample Rate Unlock. Controls 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.

LOSEL

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.

2CMIC

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 bit in Register 20h.

0 = MIC1 or MIC2 (determined by MS bit) is routed to the record selector’s left and right MIC channels as well

as to the mixer (reset default).

1 = MIC1 is routed to the record selector’s left MIC channel and MIC2 is routed to the record selector’s right

MIC channel. Note that in this mode, the MS bit should be set low and MIC1 can still be enabled into the mixer.

SPRD

SPREAD Enable. This bit enables spreading of 2-channel media to all six output channels. This function is imple-

mented in the analog section by using the output selector controls line 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 72h).

0 = No spreading occurs unless activated by the Jack Senses and JSSPRD bits (reset default).

1 = The SPRD selector drives the center and LFE outputs from the MONO_OUT, the HPSEL selector drives the

SURR/HP_OUT outputs from the mixer outputs, and the LOSEL selector drives the LINE_OUT outputs also

from the mixer outputs.

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.

Miscellaneous Control Bit Register (Index 76h)

Reg

De-

No. Name D15

D14

D13

D12

D11

D10

D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

fault

76th Misc

DACZ AC97NC MSPLT LODIS CLDIS HPSEL DMIX1 DMIX0 SPRD 2CMIC LOSEL SRU VREFH VREFD MBG1 MBG0 0000h

Control

Bits