AD1981B データシートの表示（PDF） - Analog Devices

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AD1981B

AC ’97 SoundMAX® Codec

Analog Devices 

AD1981B

Reg

No. Name

Mono Volume Register (Index 06h)

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

06h Mono Volume MVM X X X X X X X X X X MV4 MV3 MV2 MV1 MV0 8000h

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

WRITE

READBACK

Function

0

0000

0

0 1111

0

1 1111

1

x xxxx

0 0000

0 1111

1 1111

x xxxx

0 dB Gain

–22.5 dB Gain

–46.5 dB Gain

–ϱ 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

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

0Ch Phone Volume PHM X X X X X X X X X X PHV4 PHV3 PHV2 PHV1 PHV0 8008h

All registers not shown and bits containing an X are assumed to be reserved. Refer to Table III for examples.

PHV[4:0]

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.

PHM

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

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