BU26156RFS Datasheet, PDF (28/95 Pages) Rohm – Monoraul MIC Input with ALC

BU26156RFS
Datasheet
A Peak Limiter function is carried in ALC. The Peak Limitter function short attack time and prevent clipping a wave.
A threshold level is fixed at 87.5%(-1.16dBFS) and this function is priored the normal ALC operation when input level exceed
the threshold level. The attack time is a minimum step, 1/fs, when the peak limiter operates.
And this function cannot be turned off.
These operations level diagram is the following figure.
0d BFS
Peak Limiter=-1.16dBFS
Ou tpu t
(dB)
ALCLVL
In pu t
(dB)
Figure 30. ALC Level diagram
Zero Cross
BU26156 combined Zerocross function for MALC, LALC. Zerocross is changed, when input waveform is crossed center
level. In case of Zero Cross function is not occurred, BU26156 changes gain when time set by PALCZCTM is passed
BU26156 also changes gain past that time when zerocross is enable (ZCEN=0x0). It is often caused POP noise to change
gain without zero cross.
ALC GAIN
Output Signal
ALCATK ALCATK
Gain changing at
zerocross
ALCATK
ALCZCTM
Figure 31.
Note:It is possible that a noise of changing the gain occur when ZCEN is disable.
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TSZ22111・15・001
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TSZ02201-0V1V0E502570-1-2
Jul.1.2014 Rev.001