
ASAHI KASEI
[AK4645]
MS0543-E-00
2006/09
- 63 -
AK4645
HP-AMP
16
Headphone
10
0.22
μ
C
R
Figure 57. External Circuit Example of Headphone
Output Power [mW]@0dBFS
HPG bit
R [
]
C [
μ
F]
fc [Hz]
BOOST
=OFF
fc [Hz]
BOOST
=MIN
@fs=44.1kHz
17
43
28
78
19
47
17
43
25
69
HVDD=3.0V
AVDD=3.0V
HVDD=3.3V
AVDD=3.3V
HVDD=5V
AVDD=3.3V
220
100
100
47
100
47
220
100
22
10
45
100
70
149
50
106
45
100
62
137
Table 55. External Circuit Example
Note 40. Output power at 16
load.
Note 41. Output signal is clipped.
0
25.3
30.6
30.6
6.8
12.5
15.1
15.1
0
16
6.3
7.7
7.7
0
51
(Note 41)
62
(Note 41)
70
1
100
1.1
1.3
1.3
<Headphone-Amp PSRR>
When HVDD is directly supplied from the battery in the mobile phone system, RF noise may influences headphone
output performance. When VBAT bit is set to “1”, HP-Amp PSRR for the noise applied to HVDD is improved. In this
case, HP-Amp common voltage is 0.64 x AVDD (typ). When AVDD is 3.3V, common voltage is 2.1V. Therefore, when
HVDD voltage becomes lower than 4.2V, the output signal will be clipped easily.
VBAT bit
0
Common Voltage [V]
0.5 x HVDD
Table 56. HP-Amp Common Voltage
<Wired OR with External Headphone-Amp>
When PMVCM=PMHPL=PMHPR bits = “0” and HPZ bit = “1”, HP-Amp is powered-down and HPL/R pins are
pulled-down to HVSS by 200k
(typ). In this setting, it is available to connect HP-Amp of AK4645 and external single
supply HP-Amp by “wired OR”. In this mode, power supply current is 20
μ
A(typ).
PMVCM
PMHPL/R
HPMTN
HPZ
x
0
x
0
0
0
x
1
1
1
0
x
1
1
1
x
Table 57. HP-Amp Mode Setting (x: Don’t care)
1
0.64 x AVDD
Mode
HPL/R pins
HVSS
Pull-down by 200k
HVSS
Normal Operation
Power-down & Mute
Power-down
Mute
Normal Operation
Default