Datasheet

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PCM3060

SLAS533B – MARCH 2007 – REVISED MARCH 2008

B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0

AT1x[7:0]: Digital Attenuation Level Setting (ADC)

where x = 1 or 2, corresponding to the ADC output L-ch part of DOUT (x = 1) or R-ch part of DOUT (x = 2).

Default value: 1101 0111b

AT1x[7:0] DECIMAL VALUE ATTENUATION LEVEL SETTING

1111 1111b 255 20 dB

1111 1110b 254 19.5 dB

1111 1101b 253 19 dB

: : :

1101 1000b 216 0.5 dB

1101 0111b 215 0 dB, no attenuation (default)

1101 0110b 214 – 0.5 dB

: : :

0001 0000b 16 – 99.5 dB

0000 1111b 15 – 100 dB

0000 1110b 14 Mute

: : :

0000 0000b 0 Mute

Each ADC channel has a digital attenuator function with 20-dB gain. The attenuation level may be set from 20 dB

to – 100 dB in 0.5-dB steps, and also may be set to infinite attenuation (mute). The attenuation level change from

the current value to the target value is performed by incrementing or decrementing one by 0.5-dB step at the

timing of zero-cross detection on the input signal which is sampled for every 1/f

time interval, or for every 8/f

time interval if the zero-cross detection mode is disabled by ZCDD setting. If a zero-crossing is not detected for

512/f

, actual level change is done for every 1/f

time interval until a zero-crossing is detected again. While the

attenuation level change sequence is in progress, new commands for attenuation level change are not

processed, but the new command overwrites the previous command in the command buffer. The last command

for attenuation level change is performed after the present attenuation level change sequence is finished.

The attenuation level for each channel can be set individually using the following formula, and the above table

shows attenuation levels for various settings:

Attenuation level (dB) = 0.5 × (AT1x[7:0]

DEC

– 215), where AT1x[7:0]

DEC

= 0 through 255 for AT1x[7:0]

DEC

= 0

through 14, the level is set to infinite attenuation (mute).

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