REV. 0

AD1981A

–13–

RS1...RS0

Right Record Source

0

MIC

1

CD_R

2

Muted

3

AUX_R

4

LINE_IN_R

5

Stereo Mix (R)

6

Mono Mix

7

PHONE_IN

LS1...LS0

Left Record Source

0

MIC

1

CD_L

2

Muted

3

AUX_L

4

LINE_IN_L

5

Stereo Mix (L)

6

Mono Mix

7

PHONE_IN

Record Gain (Index 1Ch)

*For AC ‘97 compatibility, Bit D7 (RM) is only available by setting the MSPLT bit Register 76h. The MSPLT bit enables separate mute bits for the left and right

channels. If MSPLT is not set, RM bit has no effect.

RIM[3:0]

Right Input Mixer Gain Control: Each LSB represents 1.5 dB, 0000 = 0 dB, and the range is 0 dB to 22.5 dB.

RM

Right Channel Mute: Once enabled by the MSPLT Bit in Register 76h, this bit mutes the right channel separately

from the IM bit. Otherwise, this bit will always read “0” and will have no effect when set to “1.”

LIM[3:0]

Left Input Mixer Gain Control: Each LSB represents 1.5 dB, 0000 = 0 dB, and the range is 0 dB to 22.5 dB.

IM

Input Mute: When this bit is set to “1,” both L/R channels are muted unless the MSPLT Bit in Register 76h is set

to “1,” in which case this mute bit will only affect the left channel.

IM

xIM3...xIM0

Function

0

1111

+22.5 dB Gain

0

0000

0 dB Gain

1

xxxxx

–

∞ dB Gain

General Purpose Register (Index 20h)

*

Reg Num Name

D15 D14 D13 D12 D11 D10 D9 D8

D7

D6 D5 D4 D3 D2 D1 D0 Default

20h

General Purpose

XXXXXX

X

X

LPBK

XXXXXXX

0000h

*This register should be read before writing to generate a mask for only the bit(s) that need to be changed.

LPBK

Loop-Back Control: ADC/DAC digital loop-back mode

Reg Num Name

D15 D14 D13 D12

D11

D10

D9

D8

D7

D6 D5 D4

D3

D2

D1

D0

Default

1Ch

Record Gain

IM

X

X

X

LIM3 LIM2 LIM1 LIM0 RM

* X

X

X RIM3 RIM2 RIM1 RIM0

8000h