ak4648 AKM Semiconductor, Inc., ak4648 Datasheet - Page 71

• Manufacturer Part Number: ak4648
• Description: Stereo Codec With Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

When PMHPL and PMHPR bits are “0”, the Headphone-Amp is powered-down, and HPL and HPR pins go to “L”
(VSS2).
(1) Headphone-Amp power-up (PMHPL, PMHPR bit = “1”). The outputs are still VSS2.
(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 VSS2. If the power supply is switched
2. Pseudo Cap-less Mode (In case of using common buffer for Headphone-Amp)
When an external resistor R is smaller than 12 Ω , put an oscillation prevention circuit (0.22 μ F ± 20% capacitor and
10 Ω± 20% resistor) because it has the possibility that Headphone-Amp oscillates.
MS0625-E-01
off or Headphone-Amp is powered-down before the common voltage goes to VSS2, some POP noise occurs.
PMHPL bit,
PMHPR bit
HPMTN bit
HPL pin,
HPR pin
Figure 53. External circuit example for Headphone-Amp (Pseudo Cap-less Mode)
Figure 52. Power-up/down sequence for Headphone-Amp (Single-ended Mode)
VCOM Amp for
(1) (2)
HP-Amp
HP-Amp
HP-Amp
HVCM pin
HPR pin
HPL pin
- 71 -
(3)
0.22μF
10Ω
0.22μF
10Ω
(4)
R
R
Headphone
16Ω
16Ω
[AK4648]
2007/06