ak4564 AKM Semiconductor, Inc., ak4564 Datasheet - Page 22

• Manufacturer Part Number: ak4564
• Description: 16bit Codec With Built-in Alc And Mic/hp/spk-amp
• Manufacturer: AKM Semiconductor, Inc.

Headphone-Amps are powered-up/down by HPP bit. When HPP bit is “0”, Headphone-Amps are powered-down and
HPL and HPR pins are fixed to “L” (AVSS). At power-up/down, the common voltage of HPL/HPR pin is settled by a
constant which determined by the internal resistor and the external capacitors. The internal resistor is 50k (typ) at
power-up, and 1k (typ) at power-down. (Refer to Figure 16)
(1) Power-up Headphone-Amps: WR (HPP= “1”)
(2) Enable Headphone-Amp inputs: WR (HPDAC, HPMIX or BEEP2H =“1”)
(3) Disable Headphone-Amp inputs: WR (HPDAC=HPMIX=BEEP2H=“0”)
(4) Power-down Headphone-Amps: WR (HPP=“0”)
MS0140-E-01
Rising Time of Headphone-Amp: 1 = 50k x C1
Falling Time of Headphone-Amp: 2= 1k x (C1 + 2 x C2)
For example; C1 = 4.7 F, C2 = 100 F
HPDAC, HPMIX or BEEP2H bit
The common voltage of HPL/HPR pins rises by the time constant. ( 1)
The input signals from MIX1, DAC and BEEP2 are output. Headphone-Amps can output the signals while the
common voltage is rising.
The input signal from MIX1, DAC and BEEP2 are muted. Headphone-Amps output HVCM voltage during muting.
The common voltage of HPL/HPR pins falls by the time constant. ( 2)
1 = 235ms
2 = 205ms
From MIX1
From DAC
From BEEP2
HPL/HPR pin
HPP bit
Figure 16. Headphone-Amp internal equivalent circuit
Figure 17. Headphone-Amp Power-Up/Down Timing
HPMIX bit
HPDAC bit
BEEP2H bit
(1) (2)
HP-Amp
1
-
+
- 22 -
(3)
(4)
HPL, HPR
MUTET
+
16
C1
2
+
C2
16
2002/07