AD1985 データシートの表示（PDF） - Analog Devices

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AD1985

AC ’97 SoundMAX® Codec

Analog Devices 

AD1985

Mono Volume Register (Index 0x06)

Reg Num Name

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0 Default

0x06

Mono Volume

MVM X X X X X X X X X X MV4 MV3 MV2 MV1 MV0 0x8000

This register controls the mono output volume and mute bit.

The volume register contains five bits, generating 32 volume

levels with increments of 1.5 dB each.

AC ’97 defines the 6-bit volume registers, therefore, to maintain

compatibility whenever the D5 bit is set to 1, its 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.

Volume Settings for Mono

Control Bits D[4:0] for Mono (0x06)

D15 Write

Readback

Function

0 0 0000

0 0000

0 dB Gain

0 0 1111

0 1111

–22.5 dB Gain

0 1 1111

1 1111

–46.5 dB Gain

1 x xxxx

x xxxx

–∞ dB Gain, Muted

Note that the x in the above table is a wild card, meaning the value has no effect.

Rev. A | Page 17 of 48

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