ak4534 AKM Semiconductor, Inc., ak4534 Datasheet - Page 30

• Manufacturer Part Number: ak4534
• Description: 16bit Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
n Headphone Output
Power supply voltage for the Headphone-amp is supplied from the HVDD pin and centered on the HVDD/2 voltage. The
Headphone output load resistance is min.20 . When the HPL and HPR bits are “1”, output signals are muted and the HPL
and HPR pins output HVDD/2 voltage. When the HPL and HPR bits are “0”, the Headphone-amps are in normal
operation. When the PMHPL and PMHPR bits are “0”, the Headphone-amp is powered down and the outputs (HPL and
HPR pins) go to “L” (HVSS). A capacitor between the MUTET pin and ground reduces pop noise at power-up.
[Example] : A capacitor between the MUTET pin and ground = 1.0 F, a capacitor between the HPL (HPR) pin and
Note: The HPL and HPR bits should be kept to “0” during power-up.
(1) PMHPL and PMHPR bits = “1”
(2) PMHPL and PMHPR bits = “0”
The cut-off frequency of Headphone-amp output depends on the external resistor and capacitor used. Table 19 shows the
cut off frequency and the output power for various resistor/capacitor combinations. The headphone impedance R
Output powers are shown at HVDD = 2.7, 3.0 and 3.3V. The output voltage of headphone is 0.6 x AVDD (Vpp).
When an external resistor R is smaller than 12 , put an oscillation prevention circuit (0.22 F+10 ) because it has the
possibility that Headphone-amp oscillates.
MS0133-E-03
Headphone-amp is powered up. Common voltage of Headphone-amp is rising. This rise time depends on the capacitor
value connected with the MUTET pin. The time constant is
“C”.
Headphone-amp is powered down. Common voltage is falling. This fall time depends on the internal resistor and the
capacitor value of HPL/R pins. The time constant is
If the power supply is powered off or Headphone-Amp is powered-up again before the common voltage goes to GND,
some POP noise occurs. It takes 5times of
R [ ]
Headphone = 47 F
Time constant of rise time:
6.8
6.8
16
16
PMHPL/R bits
HPL/R pins
C [ F]
100
100
47
47
Figure 13. Power-up/Power-down Timing for Headphone-amp
Figure 14. External Circuit Example of Headphone
BOOST=OFF
HP-AMP
AK4534
fc [Hz]
148.5
105.8
69.8
49.7
r
= 100ms, Time constant of fall time:
Table 19. External Circuit Example
(1)
f
that the common voltage goes to GND.
10
0.22
BOOST=MID
f
= 2k x (2 x C) when the capacitor value on HPL(HPR) pin is “C”.
R
- 30 -
fc [Hz]
r
60
43
26
20
r
C
= 100k x C when the capacitor value on MUTET pin is
Headphone
16
2.7V
10.1
10.1
(2)
5.1
5.1
Output Power [mW]
f
f
= 188ms
3.0V
12.5
12.5
6.3
6.3
3.3V
15.0
15.0
7.7
7.7
[AK4534]
L
is 16 .
2003/5