AK4538 Datasheet, PDF (25/70 Pages) Asahi Kasei Microsystems – 16Bit DS CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4538]
n MIC Input
“ATTM” ^{“MICL”}
ATT
Stereo Mixer
Mic In
“ALC1”
“MGAIN” ^{“IPGA6-0”}
“ATTS2-0” _{“MICM”}
ATT
ADC
“MICAD”
0dB/+20dB IPGA with ALC
Figure 19. Microphone Input
Mono Mixer
µP
The AK4538 has the following functions for Mic Input.
(1) 1^st MIC Amplifier of 20dB gain that can be selected on/off by “MGAIN” bit.
(2) 2^nd Amplifier that has PGA with ALC. This volume is controlled by “IPGA6-0” bit as Table 14.
While ALC is working, Master Clock must be present.
When Master Clock isn’t provided or PMMIC= “0”, it is invalid to write to “IPGA6-0”.
(3) Attenuator for stereo mixer. This volume is controlled by “ATTS2-0” bit as Table 15.
(4) Attenuator for mono mixer. This attenuator level is 4dB and this ON/OFF is controlled by “ATTM” bit.
IPGA6-0
GAIN (dB)
STEP
47H
+27.5
46H
+27.0
45H
+26.5
:
:
36H
+19.0
:
:
10H
+0.0
Default
:
:
0.5dB
06H
−5.0
05H
−5.5
04H
−6.0
03H
−6.5
02H
−7.0
01H
−7.5
00H
−8.0
Table 14. Microphone Input Gain Setting
ATTS2-0
Attenuation
7H
-6dB
6H
−9dB
5H
−12dB
Default
4H
−15dB
3H
−18dB
2H
−21dB
1H
−24dB
0H
-27dB
Table 15. Attenuator Table
MS0198-E-01
- 25 -
2003/5