AK4691EG AKM [Asahi Kasei Microsystems], AK4691EG Datasheet - Page 56

• Manufacturer Part Number: AK4691EG
• Description: 4ch ADC + 2ch DAC with MIC/HP/SPK-AMP
• Manufacturer: AKM [Asahi Kasei Microsystems]

(1) Headphone-Amp power-up (PMHPL, PMHPR bit = “1”). The outputs are still VSS4.
(2) Headphone-Amp common voltage rises up (HPMTN bit = “1”). Common voltage of Headphone-Amp is rising.
(3) Headphone-Amp common voltage falls down (HPMTN bit = “0”). Common voltage of Headphone-Amp is falling.
(4) Headphone-Amp power-down (PMHPL, PMHPR bit = “0”). The outputs are VSS4. If the power supply is switched
When BOOST=OFF, the cut-off frequency (fc) of Headphone-Amp depends on the external resistor and capacitor. This
fc can be shifted to lower frequency by using bass boost function.
power for various resistor/capacitor combinations. The headphone impedance R
AVDD = LVDD = 2.7, 3.0 and 3.3V. The output voltage of headphone is 0.6 x AVDD (Vpp)@HPG bit = “0”, 0.91 x
AVDD(Vpp)@HPG bit = “1”.
When an external resistor R is smaller than 12Ω, put an oscillation prevention circuit (0.22μF±20% capacitor and
10Ω±20% resistor) because there is a possibility that Headphone-Amp oscillates.
MS0672-E-00
off or Headphone-Amp is powered-down before the common voltage settles to VSS4, some POP noise occurs.
HPG bit
0
1
PMHPL bit,
PMHPR bit
HPMTN bit
HPL pin,
HPR pin
R [ Ω ]
100
6.8
16
0
Figure 37. Power-up/Power-down Timing for Headphone-Amp
C [ μ F]
100
100
220
100
47
47
22
10
(1) (2)
Figure 38. External Circuit Example of Headphone
HP-AMP
AK4691
BOOST=OFF
Table 51. External Circuit Example
fc [Hz]
149
106
100
137
70
50
45
62
10Ω
0.22μ
R
- 56 -
(3)
BOOST=MIN
@fs=44.1kHz
fc [Hz]
C
28
78
19
47
17
43
25
69
Table 51
Headphone
(4)
16Ω
shows the cut off frequency and the output
L
2.7V
10.1
5.1
0.9
is 16Ω. Output powers are shown at
33
Output Power [mW]@0dBFS
3.0V
12.5
6.3
1.1
41
3.3V
15.1
7.7
1.3
50
[AK4691]
2007/11