AD1981B データシートの表示（PDF） - Analog Devices
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AD1981B Datasheet PDF : 28 Pages
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AD1981B
MIC Volume Register (Index 0Eh)
Reg
No. Name
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4
D3
D2
D1 D0 Default
0Eh MIC Volume MCM X X X X X X X X M20 X MCV4 MCV3 MCV2 MCV1 MCV0 8008h
All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.
MCV[4:0]
M20
MCM
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.
Table III. Volume Settings for Phone and MIC
Control Bits D[4:0]
Phone (0Ch) and Mic (0Eh)
D15
WRITE
READBACK
Function
0
0 0000
0
0 1000
0
1 1111
1
x xxxx
0 0000
0 1000
1 1111
x xxxx
12 dB Gain
0 dB Gain
–34.5 dB Gain
–ϱ dB Gain, Muted
x in the above table is a wild card, and has no effect on the value.
Line-In Volume Register (Index 10h)
Reg
No. Name
D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default
10h Line-In Volume LVM X X LLV4 LLV3 LLV2 LLV1 LLV0 RM* X X RLV4 RLV3 RLV2 RLV1 RLV0 8808h
*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
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.
RLV[4:0]
RM
LLV[4:0]
LVM
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
Register 76h is set to 1, in which case this mute bit will affect only the left channel.
REV. B
–13–
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