BU26156RFS Datasheet, PDF (30/95 Pages) Rohm – Monoraul MIC Input with ALC

BU26156RFS
Datasheet
MALC (Mic Input ALC)/LALC (Line input ALC)
Function general description
MALC can be adjusted mic input gain from 0dB to +35.25dB. LALC can be adjusted line input gain from -15dB to 0dB.
Operation general description
MALC and LALC are fixed ADC full-scale level. When output waveform level of ALC is under the target level, output
waveform is increased. Maximum level of gain is MALCMXGAIN or LALCMXGAIN. Minimum level of gain is 0dB, when
MALC is used. Minimum level of gain is -15dB, when LALC is used. MALCATK and LALCATK are attack time. It is a time
step of decreasing waveform level. MALCDCY and LALCDCY is decay time. It is a time step of increasing waveform level.
These operations are the following.
* In case of MALC, LALC are disabled, output waveform is effective MALCMXGAIN and LALCMXGAIN setting gain.
Input waveform
MALC/LALC
Gain
MALC/LALC
Output
Maximum gain
(MALCMXGAIN
/LALCMXGAIN)
Minimum gain
(Fix to MALC=0dB
/LALC=-15dB)
Target Level
(Fix to ADC full-scale
level)
Attack time period
(MALCATK/LALCATK)
Figure 33.
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 is changed gain after 2.7ms @Fs=48 kHz.
Clip reduction
Clip reduction function prevents clip waveform. When BU26156 is entered large waveform, BU26156 is shorted attack time.
As result of this operaiontion, output waveform is prevented clip waveform. When this function is enabled, attack time is fixed
2fs and zerocross is disabled. The difference between peak limiter and clip reduction is threshold and attacktime. Threshold
of Clip deduction is ADC full scale level. Attack time of clip reduction is 2fs. It is possible to select ON/OFF register setting.
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TSZ22111・15・001
30/92
TSZ02201-0V1V0E502570-1-2
Jul.1.2014 Rev.001