AD1981B
Mono Volume Register (Index 06h)
Reg
No. Name
06h
D15
D14 D13
X
X
D12
X
D11
X
D10
X
D9
X
D8
X
D7
X
D6
X
D5
X
D4
MV4
D3
MV3
D2
MV2
D1
MV1
D0
MV0
Default
8000h
Mono Volume MVM
All registers not shown and bits containing an X are assumed to be reserved.
Refer to Table II for examples. This register controls the mono output volume and mute bit. The volume register contains five bits,
generating 32 volume levels with 31 steps of 1.5 dB each. Because AC ’97 defines 6-bit volume registers, to maintain compatibility,
whenever the D5 bit is set to 1, their respective lower five volume bits are automatically set to 1 by the codec logic. On readback, all
lower five bits will read 1s whenever this bit is set to 1.
MV[4:0]
MVM
Mono Volume Control. The least significant bit represents 1.5 dB. This register controls the output from 0 dB to a
maximum attenuation of 46.5 dB.
Mono Volume Mute. When this bit is set to 1, the channel is muted.
Table II. Volume Settings for Mono
Control Bits D[4:0] for Mono (06h)
D15
0
0
0
1
WRITE
0000
0 1111
1 1111
x xxxx
READBACK
0 0000
0 1111
1 1111
x xxxx
Function
0 dB Gain
–22.5 dB Gain
–46.5 dB Gain
– dB Gain, Muted
x in the above table is a wild card and has no effect on the value.
Phone Volume Register (Index 0Ch)
Reg
No. Name
0Ch Phone Volume
D15
PHM
D14 D13
X
X
D12
X
D11
X
D10
X
D9
X
D8
X
D7
X
D6
X
D5
X
D4
PHV4
D3
PHV3
D2
PHV2
D1
D0
Default
8008h
PHV1 PHV0
All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.
PHV[4:0]
PHM
Phone Volume. Allows setting the phone volume attenuator in 32 volume levels with 31 steps of 1.5 dB each. The
LSB represents 1.5 dB, and the gain range is +12 dB to –34.5 dB. The default value is 0 dB, with the mute bit enabled.
Phone Mute. When this bit is set to 1, the phone channel is muted.
All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.
–12–
REV. B
AD [ ANALOG DEVICES ]
