AD1981A Analog Devices, AD1981A Datasheet - Page 10

• Manufacturer Part Number: AD1981A
• Description: AD1981A AC'97 Soundmax Codec
• Manufacturer: Analog Devices

AD1981A
NOTES
1
2
RHV [4:0]
RM
LHV [4:0]
HPM
MV[4:0]
MVM
Reg Num Name
channels. If MSPLT is not set, RM bit has no effect.
This register controls the headphone volume controls for both stereo channels and mute bit. Each volume subregister contains 5 bits, generating 32 volume levels
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
Reg Num Name
Reg Num Name
with 31 steps of 1.5 dB each. Because AC ‘97 defines 6-bit volume registers, to maintain compatibility whenever the D5 or D13 Bits are set to “1, ” their respective
lower five volume bits are automatically set to “1” by the CODEC logic. On readback, all lower 5 bits will read ones when ever these bits are set to “1.”
This register controls the headphone volume controls for both stereo channels and mute bit. Each volume subregister contains 5 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 or D13 Bits are set to “1, ” their respective
lower five volume bits are automatically set to “1” by the CODEC logic. On readback, all lower 5 bits will read ones when ever these bits are set to “1.”
0Ch
04h
06h
Headphones Volume HPM X
Phone Volume PHM
Mono Volume MVM
Right Headphone 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.
Right Channel Mute: Once enabled by the MSPLT Bit in Register 76h, this bit mutes the right channel separately
from the HPM Bit. Otherwise, this bit will always read “0” and will have no effect when set to “1.”
Left Headphone 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.
Headphones Volume 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.
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.
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5
HPM
0
0
0
0
1
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5
MVM
0
0
0
0
1
D15 D14 D13 D12
X
X
X LHV4 LHV3 LHV2 LHV1 LHV0 RM
xHV5…xHV0 Function
WRITE
00 0000
00 1111
01 1111
1x xxxx
xx xxxx
WRITE
00 0000
00 1111
01 1111
1x xxxx
xx xxxx
X
X
Headphones Volume Register (Index 04h)
X
xMV5…xMV0
X
Phone Volume (Index 0Ch)
D11
X
Mono Volume (Index 06h)
X
READBACK
00 0000
00 1111
01 1111
01 1111
xx xxxx
READBACK
00 0000
00 1111
01 1111
01 1111
xx xxxx
X
D10
X
X
D9
X
X
X
X
D8
X
X
Function
0 dB Gain
–22.5 dB Gain
–46.5 dB Gain
–46.5 dB Gain
–∞ dB Gain
Function
0 dB Gain
–22.5 dB Gain
–46.5 dB Gain
–46.5 dB Gain
–∞ dB Gain
D7 D6 D5
X
X PHV4 PHV3 PHV2 PHV1 PHV0 8008h
2
X X RHV4 RHV3 RHV2 RHV1 RHV0 8000h
X MV4 MV3 MV2 MV1 MV0 8000h
D4
1
D4
D4
D3
D3
D3
D2
D2
D2
D1
D1
D1
D0
D0 Default
D0
Default
Default