[AK4675]
■ Headphone Volume (LIN1A/RIN1A pins)
The AK4675 has the mixing circuits for headphone amplifier. The each mixing circuit can be controlled independently.
When all input paths are OFF, the mixing circuit outputs VCOMA voltage. The volume of each input pin can be
controlled independently. The input volume range is from +10 dB to –20dB by 2dB step. When the input volume is
changed, pop noise may occur. The input volume has power management mode that is common to the left and right
channels. The power-up/down of input volume can be controlled by PMV1 bit. The power-up time of the input volume is
16.4ms (typ.) and 26.3ms(max) at OSCN bit = “0”. when OSCN bit = “1”, power-up time depends on both the MSEL bit
setting and the MCKIA frequency (Table 75). During power-up time, the input volume block outputs VCOMA voltage
regardless of the input signal. AC coupling capacitor of 0.22μF or less should be connected at the LIN1A/RIN1A pins to
reduce pop noise at the power-up of the input volume block.
MSEL bit
0
MCKIA Freq
Power-Up Time
2.048MHz
2.8224MHz
3.072MHz
16ms (32768/MCKIA)
17.1ms (49152/MCKIA)
16ms (49152/MCKIA)
1
Table 75. Input Volume Power-Up Time (OSCN bit = “1”)
L1V3-0 bits
R1V3-0 bits
GAIN (dB)
Step
2dB
FH
EH
:
CH
BH
AH
9H
8H
:
+10
+8
-
+4
+2
0
−2
−4
:
(default)
2H
1H
0H
−16
−18
−20
Table 76. Input Volume Setting
HPLL1bit
PREL
Mixing
LIN1A
VOL(L1V3-0 bits)
&
To Lch Headphone-Amp
To Rch Headphone-Amp
HPLR1 bit
Selector
HPRL1 bit
Mixing
&
HPRR1 bit
RIN1A
VOL(R1V3-0 bits)
Selector
Figure 80. Input Selector & Volume
MS0963-E-00
2008/05
- 108 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
