ak4650 AKM Semiconductor, Inc., ak4650 Datasheet - Page 39

• Manufacturer Part Number: ak4650
• Description: 16bit 6 Codec With Mic/hp/spk-amp & Tsc
• Manufacturer: AKM Semiconductor, Inc.

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Power supply voltage for the Headphone-amp is supplied from the HVDD pin and centered on the MUTET voltage. The
Headphone-amp output load resistance is min.16 . When the HPMT bit is “1” at PMHPL=PMHPR= “1”, the common
voltage rises to 0.44 x AVDD. When the HPMT bit is “1”, the common voltage of Headphone-amp falls and the outputs
(HPL and HPR pins) go to HVSS.
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 32 depend on the
capacitance and ESR of the external capacitor at MUTET pin.
[Example]: A capacitor between the MUTET pin and ground = 1.0 F:
When PMHPL and PMHPR bits are “0”, the Headphone-amp is powered-down, and the outputs (HPL and HPR pins) go
to HVSS.
(1) Headphone-amp power-up (PMHPL and PMHPR bits = “1”). The outputs are still HVSS.
(2) Headphone-amp common voltage rises up (HPMT bit = “0”). Common voltage of Headphone-amp is rising. This rise
(3) Headphone-amp common voltage falls down (HPMT bit = “1”). Common voltage of Headphone-amp is falling to
(4) Headphone-amp power-down (PMHPL, PMHPR bits = “0”). The outputs are HVSS. If the power supply is switched
MS0502-E-01
Headphone Output
time depends on the capacitor value connected with the MUTET pin. The rise time up to 0.44 x AVDD is t
C(typ) when the capacitor value on MUTET pin is “C”.
HVSS. This fall time depends on the capacitor value connected with the MUTET pin. The fall time down to 0V is t
200k x C(typ) when the capacitor value on MUTET pin is “C”.
off or Headphone-amp is powered-down before the common voltage goes to HVSS, some pop noise occurs.
Rise Time up to 0.44 x AVDD: t
Fall Time down to 0V: t
PMHPL/R bit
HPMT bit
HPL/R pin
t
t
r
f
: Rise Time up to 0.44 x AVDD
: Fall Time down to 0V
0.22 x AVDD
0.44 x AVDD
Figure 26. Power-up/Power-down Timing for Headphone-amp
f
= 200k x 1 F = 200ms(typ)
Table 32. Headphone-Amp Rise/Fall Time
(1) (2)
r
= 100k x 1 F = 100ms(typ)
t
r
- 39 -
100k x C (typ)
200k x C (typ)
(3)
t
f
(4)
[AK4650]
r
= 100k x
2007/04
f
=