[AK4372]
■ Headphone Output (HPL, HPR pins)
The power supply voltage for the headphone-amp is supplied from the AVDD pin and is centered on the MUTET voltage.
The headphone-amp output load resistance is 16Ω (min). When the MUTEN bit is “1” at PMHPL=PMHPR= “1”, the
common voltage rises to 0.475 x AVDD. When the MUTEN bit is “0”, the common voltage of the headphone-amp falls
and the outputs (HPL and HPR pins) go to VSS1.
tr: Rise Time up to VCOM/2
tf: Fall Time down to VCOM/2
70k x C (typ)
60k x C (typ)
Table 22. Headphone-Amp Rise/Fall Time
[Example] : Capacitor between the MUTET pin and ground = 1μF:
Rise time up to VCOM/2: tr = 70k x 1μ = 70ms(typ).
Fall time down to VCOM/2: tf = 60k x 1μ = 60ms(typ).
When the PMHPL and PMHPR bits are “0”, the headphone-amp is powered-down, and the outputs (HPL and HPR pins)
go to VSS1.
PMHPL/R bit
MUTEN bit
VCOM
VCOM/2
HPL/R pin
tf
tr
(4)
(1) (2)
(3)
Figure 22. Power-up/Power-down Timing for the Headphone-Amp
(1) Headphone-amp power-up (PMHPL and PMHPR bits = “1”). The outputs are still at VSS1.
(2) Headphone-amp common voltage rises up (MUTEN bit = “1”). Common voltage of the headphone-amp is rising. This
rise time depends on the capacitor value connected with the MUTET pin. The rise time up to VCOM/2 is tr = 70k x
C(typ) when the capacitor value on MUTET pin is “C”.
(3)Headphone-amp common voltage falls down (MUTEN bit = “0”). Common voltage of the headphone-amp is falling
to VSS1. This fall time depends on the capacitor value connected with the MUTET pin. The fall time down to
VCOM/2 is tf = 60k x C(typ) when the capacitor value on the MUTET pin is “C”.
(4)Headphone-amp power-down (PMHPL, PMHPR bits = “0”). The outputs are at VSS1. If the power supply is switched
off or the headphone-amp is powered-down before the common voltage settles to VSS1, some pop noise may occur.
MS0684-E-02
2008/12
- 29 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
