AK4538 Datasheet, PDF (64/70 Pages) Asahi Kasei Microsystems – 16Bit DS CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4538]
n MIC Input Recording
FS2-0 bits ₀₀₀
(Addr:05H, D7-5)
(1)
MIC Control
(Addr:07H, D2-0)
00001
(2)
XXX
XX1XX
Example :
X’tal and PLL are used.
Sampling Frequency : 8kHz
Mic Select : Internal Mic
Pre Mic AMP : +20dB
MIC Power On
ALC1 setting : Refer to Figure 9
ALC2 bit = “1”(default)
ALC1 Control 1 _XXH
(Addr:08H)
(3)
00H
(1) Addr:05H, Data:E0H
ALC1 Control 2
(Addr:0AH)
ALC1 Control 3
(Addr:09H)
ALC1 State
XXH
(4)
XXH
(5)
ALC1 Disable
47H
61H or 21H
ALC1 Enable ALC1 Disable
(2) Addr:07H, Data:0DH
(3) Addr:08H, Data:00H
(4) Addr:0AH, Data:47H
PMADC bit
(Addr:00H, D0)
PMMIC bit
(Addr:00H, D1)
(6)
(7)
2081 / fs
(5) Addr:09H, Data:61H
(6) Addr:00H, Data 83H
Recording
ADC Internal
State
Power Down
Initialize Normal State Power Down
(7) Addr:00H, Data 80H
Figure 53. MIC Input Recording Sequence
<Example>
This sequence is an example of ALC1 setting at fs=8kHz. If the parameter of the ALC1 is changed, please refer to
“Figure 21. Registers set-up sequence at the ALC1 operation.”
At first, clocks should be supplied according to “Clock Set Up” sequence.
(1) Set up a sampling frequency (FS2-0 bits). When the AK4538 is PLL mode, MIC and ADC should be powered-up
in consideration of PLL lock time after a sampling frequency is changed.
(2) Set up MIC input (Addr: 07H)
(3) Set up Timer Select for ALC1 (Addr: 08H)
(4) Set up REF value for ALC1 (Addr: 0AH)
(5) Set up LMTH, RATT, LMAT1-0, ALC1 bits (Addr: 09H)
(6) Power Up MIC and ADC: PMMIC bit = PMADC bit = “0” → “1”
The initialization cycle time of ADC is 2081/fs=47.2ms@fs=44.1kHz.
After the ALC1 bit is set to “1” and MIC block is powered-up, the ALC1 operation starts from IPGA initial
value (0dB).
(7) Power Down MIC and ADC: PMMIC bit = PMADC bit = “1” → “0”
When the registers for the ALC1 operation are not changed, ALC1 bit may be keeping “1”. The ALC1
operation is disabled because the MIC block is powered-down. If the registers for the ALC1 operation are also
changed when the sampling frequency is changed, it should be done after the AK4538 goes to the manual mode
(ALC1 bit = “0”) or MIC block is powered-down (PMMIC bit = “0”). IPGA gain is reset when PMMIC bit is
“0”, and then IPGA operation starts from the default value when PMMIC is changed to “1”.
MS0198-E-01
- 64 -
2003/5