Datasheet

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PCM1870
SLAS544A – MAY 2007 – REVISED SEPTEMBER 2007
Register 83
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
Register 83 0 IDX6 IDX5 IDX4 IDX3 IDX2 IDX1 IDX0 RALC RSV RRTC RATC RCP1 RCP0 RLV1 RLV0
IDX[6:0]: 1010011b (53h) Register 83
RALC: Automatic Level Control (ALC) Enable for Recording
Default value: 0
Auto level control can be enabled with some parameters for microphone input or lower-level analog source.
RALC = 0 Disabled (default)
RALC = 1 Enabled
RRTC: ALC Recovery Time Control for Recording
Default value: 0
This bit selects the time during which a gain level change completes to compress the signal when the input to the
ADC increases in amplitude.
RRTC = 0 3.4 s (default)
RRTC = 1 13.6 s
RATC: ALC Attack Time Control for Recording
Default value: 0
This bit selects the time during which a gain level change completes to expand the signal when the input to the
ADC decreases in amplitude.
RATC = 0 1 ms (default)
RATC = 1 2 ms
RCP[1:0]: ALC Compression Level Control for Recording
Default value: 00
Auto level control can set the compression level to – 2, – 6, or – 12 dB. Higher-level signals should be compressed
to avoid saturation or degradation of sound quality.
RCP[1:0] ALC Compression Level Control for Recording
0 0 – 2 dB (default)
0 1 – 6 dB
1 0 – 12 dB
1 1 Reserved
RLV[1:0]: ALC Expansion Level Control for Recording
Default value: 00
Auto level control can set the expansion level to 0, 6, 14, or 24 dB. Lower-level signals should be expanded to
make a small signal easy to hear. If set to 0 dB, the ALC can be operated only as a limiter.
RLV[1:0] ALC Expansion Level Control for Recording
0 0 0 dB (default)
0 1 6 dB
1 0 14 dB
1 1 24 dB
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Product Folder Link(s): PCM1870