AK4366_04 Datasheet, PDF (18/31 Pages) Asahi Kasei Microsystems – Low Power 24-Bit 2ch DAC with HP-AMP

ASAHI KASEI
[AK4366]
„ Headphone Output
Power supply voltage for the Headphone-amp is supplied from the HVDD pin and centered on the 0.45 x VDD voltage.
The Headphone-amp output load resistance is min.16Ω.
1) Parallel mode (P/S pin = “H”)
When MUTEN pin is set to “H” at PDN pin = “H”, common voltage goes to 0.45 x VDD. When MUTEN pin is set to “L”,
common voltage goes to VSS, and the outputs (HPL and HPR pins) are VSS. When PDN pin is “L”, headphone
amplifiers are powered-down perfectly, and the outputs (HPL and HPR pins) are VSS.
2) Serial mode (P/S pin = “L”)
When the MUTEN bit is “1” at PMHPL=PMHPR= “1”, the common voltage rises to 0.45 x VDD. When the MUTEN bit
is “0”, the common voltage of Headphone-amp falls and the outputs (HPL and HPR pins) go to VSS. When PMHPL and
PMHPR bits are “0”, the Headphone-amps are powered-down perfectly, and the outputs (HPL and HPR pins) are VSS.
A capacitor between the MUTET pin and ground reduces pop noise at power-up/down. It is
recommended that the capacitor with small variation of capacitance and low ESR (Equivalent Series
Resistance) over all temperature range, since the rise and fall time in Table 10 depend on the
capacitance and ESR of the external capacitor at MUTET pin.
t_r: Rise Time up to VCOM/2
100k x C (typ)
t_f: Fall Time down to 0V
200k x C (typ)
Table 10. Headphone-Amp Rise/Fall Time
[Example] : A capacitor between the MUTET pin and ground = 1.0µF:
Time constant of rise time: t_r = 100kΩ x 1µF = 100ms(typ)
Time constant of fall time: t_f = 200kΩ x 1µF = 200ms(typ)
PMHPL/R bit
MUTEN bit
VCOM
HPL/R pin ^VCOM/2
t_r
(1) (2)
t_f
(3)
(4)
Figure 14. Power-up/Power-down Timing for Headphone-amp
(1) Headphone-amp power-up (PMHPL and PMHPR bits = “1”). The outputs are still VSS.
(2) Headphone-amp common voltage rise up (MUTEN bit = “1”). Common voltage of 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 t_r = 100k x C(typ)
when the capacitor value on MUTET pin is “C”.
(3) Headphone-amp common voltage fall down (MUTEN bit = “0”). Common voltage of Headphone-amp is falling to
VSS. This fall time depends on the capacitor value connected with the MUTET pin. The fall time down to 0V is t_f =
200k x C(typ) when the capacitor value on MUTET pin is “C”.
(4) Headphone-amp power-down (PMHPL, PMHPR bits = “0”). The outputs are VSS. If the power supply is switched off
or Headphone-amp is powered-down before the common voltage goes to VSS, some pop noise occurs.
MS0248-E-01
- 18 -
2004/03