AD1981B Analog Devices, AD1981B Datasheet - Page 13

• Manufacturer Part Number: AD1981B
• Description: AD1981B AC'97 SoundMAX® Codec
• Manufacturer: Analog Devices

*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
REV. A
MCV[4:0]
M20
MCM
*For AC ’97 compatibility, Bit D7 (RM) is available only by setting the MSPLT bit, Register 76h. The MSPLT bit enables separate mute bits for the left and right
RLV[4:0]
RM
LLV[4:0]
LM
Register
Reg
No. Name
12h CD Volume
channels. If MSPLT is not set, the RM Bit has no effect. All registers not shown and bits containing an X are assumed to be reserved. Refer to Table IV for examples.
Reg
No. Name
10h Line In Volume LVM X
channels. If MSPLT is not set, the RM bit has no effect. All registers not shown and bits containing an X are assumed to be reserved. Refer to Table IV for examples.
MIC Volume Gain. 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.
MIC Gain Boost. This bit allows setting additional MIC gain to increase the microphone sensitivity. The nominal
gain boost by default is 20 dB; however, bits D0 and D1 (MBG[1:0]) on the miscellaneous control bits register
(76h) allow changing the gain boost to 10 dB or 30 dB if necessary.
0 = Disabled; Gain = 0 dB
1 = Enabled; Default Gain = 20 dB (see Register 76h, bits D0, D1)
MIC Mute. When this bit is set to “1,” the MIC channel is muted.
Line In Volume Right. Allows setting the line in right channel attenuator in 32 volume levels. The LSB represents
1.5 dB, and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
Right Channel Mute. Once enabled by the MSPLT bit in Register 76h, this bit mutes the right channel separately
from the LM bit. Otherwise, this bit will always read “0” and will have no effect when set to “1.”
Line In Volume Left. Allows setting the line in left channel attenuator in 32 volume levels. The LSB represents
1.5 dB, and the range is +12 dB to –34.5 dB. The default value is 0 dB, mute enabled.
Line In Mute. When this bit is set to “1,” both the left and right channels are muted unless the MSPLT bit in
76h is set to “1,” in which case this mute bit will affect only the left channel.
D15
CVM X
D15
D14 D13 D12
D14 D13 D12
D15
0
0
0
1
x in the above table is a wild card, and has no effect on the value.
X
X
LCV4 LCV3 LCV2 LCV1 LCV0 RM* X
LLV4 LLV3 LLV2 LLV1 LLV0 RM* X
WRITE
0 0000
0 1000
1 1111
x xxxx
Table III. Volume Settings for Phone and MIC
Phone (0Ch) and Mic (0Eh)
D11
D11
Control Bits D[4:0]
Line-In Volume Register (Index 10h)
CD Volume Register (Index 12h)
D10
D10
D9
D9
READBACK
0 0000
0 1000
1 1111
x xxxx
–13–
D8
D8
D7
D7
D6
D6
X
D5
Function
12 dB Gain
0 dB Gain
–34.5 dB Gain
– dB Gain, Muted
D5
X
D4
RCV4 RCV3 RCV2 RCV1 RCV0 8808h
D4
RLV4
D3
D3
RLV3
D2
D2
RLV2 RLV1 RLV0 8808h
D1
D1
AD1981B
D0
D0
Default
Default