ak4538 AKM Semiconductor, Inc., ak4538 Datasheet - Page 64

• Manufacturer Part Number: ak4538
• Description: 16bit ?? Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
n MIC Input Recording
MS0198-E-01
ALC1 Control 1
ALC1 Control 2
ALC1 Control 3
(Addr:05H, D7-5)
(Addr:07H, D2-0)
ADC Internal
MIC Control
(Addr:00H, D0)
(Addr:00H, D1)
ALC1 State
PMADC bit
<Example>
PMMIC bit
FS2-0 bits
(Addr:0AH)
(Addr:08H)
(Addr:09H)
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.
State
(1) Set up a sampling frequency (FS2-0 bits). When the AK4538 is PLL mode, MIC and ADC should be powered-up
(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”
(7) Power Down MIC and ADC: PMMIC bit = PMADC bit = “1”
in consideration of PLL lock time after a sampling frequency is changed.
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”.
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).
000
00001
XXH
XXH
XXH
ALC1 Disable
Power Down
(1)
(2)
(3)
(4)
(5)
(6)
Initialize Normal State Power Down
2081 / fs
Figure 53. MIC Input Recording Sequence
ALC1 Enable
XXX
61H or 21H
XX1XX
00H
47H
- 64 -
ALC1 Disable
(7)
“1”
“0”
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)
(1) Addr:05H, Data:E0H
(2) Addr:07H, Data:0DH
(3) Addr:08H, Data:00H
(4) Addr:0AH, Data:47H
(5) Addr:09H, Data:61H
(6) Addr:00H, Data 83H
(7) Addr:00H, Data 80H
Recording
[AK4538]
2003/5