PCM1740

12

SBAS128B

www.ti.com

REGISTER DEFINITIONS

B15

B14

B13

B12

B11

B10

B9

B8

B7

B6

B5

B4

B3

B2

B1

B0

Register 0

res

res

res

res

res

0

0

0

AL7

AL6

AL5

AL4

AL3

AL2

AL1

AL0

Left Channel Attenuation Data

Default: AL[7:0] = FFHEX

Register 0 is used to set the digital attenuation level for the Left Channel. If the ATC bit in Register 3 is set to ‘1’, then these

data are also used to control the Right Channel attenuation. The attenuation level is defined by the following relationships:

Attenuation (dB) = 20 x log (AL[7:0]DEC ÷ 256), when AL[7:0] = 01HEX (1DEC) through FEHEX (254DEC)

Attenuation (dB) = –

∞ (or Mute), when AL[7:0] = 00

HEX

Attenuation (dB) = 0dB, when AL[7:0] = FFHEX

The Attenuation Load bit, LD, in Register 4 must be set to ‘1’ in order to update attenuation settings.

If LD is set to ‘0’, the attenuation remains at the previously programmed level, ignoring the new data until LD is set to ‘1’.

B15

B14

B13

B12

B11

B10

B9

B8

B7

B6

B5

B4

B3

B2

B1

B0

Register 1

res

res

res

res

res

0

0

1

AR7

AR6

AR5

AR4

AR3

AR2

AR1

AR0

Right Channel Attenuation Data

Default: AR[7:0] = FFHEX

Register 1 is used to set the digital attenuation level for the Right Channel. If the ATC bit in Register 3 is set to ‘1’, then the

Left Channel attenuation data in Register 1 are used to control the Right Channel attenuation. The attenuation level is defined

by the following relationships:

Attenuation (dB) = 20 x log (AR[7:0]DEC ÷ 256), when AR[7:0] = 01HEX (1DEC) through FEHEX (254DEC)

Attenuation (dB) = –

∞ (or Mute), when AR[7:0] = 00

HEX

Attenuation (dB) = 0dB, when AR[7:0] = FFHEX

The Attenuation Load bit, LD, in Register 4 must be set to ‘1’ in order to update attenuation settings.

If LD is set to ‘0’, the attenuation remains at the previously programmed level, ignoring the new data until LD is set to ‘1’.

MUT

Soft Mute Control

The MUT bit controls the soft mute function. Soft mute changes the digital attenuation level for both the Left

and Right channels, stepping from the currently programmed value to infinite attenuation one step per sample

period, or 1/fS. This provides a quiet muting of the outputs without audible noise.

MUT = 0

Soft Mute Disabled (default)

MUT = 1

Soft Mute Enabled

DEM

Digital De-Emphasis

The DEM bit controls the digital de-emphasis function, which is valid only for 32kHz, 44.1kHz,

and 48kHz sampling frequencies. The de-emphasis plots are shown in the Typical Characteristics section of this

data sheet.

DEM = 0

De-Emphasis OFF (default)

DEM = 1

De-Emphasis ON

B15

B14

B13

B12

B11

B10

B9

B8

B7

B6

B5

B4

B3

B2

B1

B0

Register 2

res

res

res

res

res

0

1

0

PL3

PL2

PL1

PL0

IW1

IW0

DEM

MUT