AK4537 Datasheet, PDF (32/76 Pages) Asahi Kasei Microsystems – 16-Bit ΔΣ Stereo CODEC with MIC/HP/SPK-AMP

ASAHI KASEI
[AK4537]
„ 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.20Ω. When the PMHPL and PMHPR bits are “0”, the common voltage of
Headphone-amp falls and the outputs (HPL and HPR pins) go to “L” (HVSS). When the PMHPL and PMHPR bits are
“1”, the common voltage rises to HVDD/2. A capacitor between the MUTET pin and ground reduces pop noise at
power-up.
[Example] : A capacitor between the MUTET pin and ground = 1.0µF:
Rise/fall time constant: τ = 100ms(typ), 250ms(max)
Time until the common goes to HVSS when PMHPL/R bits = “1” Æ “0”: 500ms(max)
When HPL and HPR bits are “1”, the Headphone-amp is powered-down, and the outputs (HPL and HPR pins) go to “L”
(HVSS).
PMHPL/R bit
HPL/R bit
HPL/R pin
(1) (2)
(3)
(4)
Figure 26. Power-up/Power-down Timing for Headphone-amp
(1) Headphone-amp power-up (HPL, HPR bit= “0”). The outputs are still HVSS.
(2) Headphone-amp common voltage rise up (PMHPL, PMHPR bit= “1”). Common voltage of Headphone-amp is rising.
This rise time depends on the capacitor value connected with the MUTET pin. The time constant is τ = 100k x C when
the capacitor value on MUTET pin is “C”.
(3) Headphone-amp common voltage fall down (PMHPL, PMHPR bit= “0”). Common voltage of Headphone-amp is
falling. This fall time depends on the capacitor value connected with the MUTET pin. The time constant is τ = 100k x
C when the capacitor value on MUTET pin is “C”.
(4) Headphone-amp power-down (HPL, HPR bit= “1”). The outputs are HVSS. If the power supply is switched off or
Headphone-amp is powered-down before the common voltage goes to HVSS, some POP noise occurs.
MS0202-E-04
- 32 -
2005/04