ak4569 AKM Semiconductor, Inc., ak4569 Datasheet - Page 21

• Manufacturer Part Number: ak4569
• Description: 20-bit Stereo Codec With Ipga & Hp-amp
• Manufacturer: AKM Semiconductor, Inc.

ASAHI KASEI
The AK4569 includes a digital de-emphasis filter (tc = 50/15µs) by IIR filter corresponding to three sampling frequencies
(32kHz, 44.1kHz and 48kHz). The de-emphasis filter is enabled by setting DEM1-0 bits (Table 16).
By controlling BST1-0 bits, the low frequency boost signal can be output from DAC. The setting value is common in Lch
and Rch (Table 17).
The cut-off frequency (fc) of HPF depends on the external resistor and capacitor values. Table 4 shows the relationship of
external resistor, capacitor, fc and output power, where load resistance of headphone is 16Ω. Output level of headphone
amp is 1.5Vpp (typ).
The AK4569 should be reset once by bringing PDN “L” upon power-up. After exiting reset, VCOM, IPGA, ADC, DAC,
HPL, HPR and MOUT switch to the power-down state. The contents of the control register are maintained until the reset
is done.
ADC exits reset and power down state by MCLK after PMADC bit is changed to “1”, and then ADC is powered up and
the internal timing starts clocking by LRCK “↑”. ADC is in the power-down mode until MCLK and LRCK are input.
DAC also exits reset and power down state when MCLK and LRCK are input after PMDAC= “1”.
MS0292-E-01
De-emphasis Filter
Bass Boost Function
System Reset
R [Ω]
6.8
16
Table 4. Relationship of external circuit, output power and frequency response
Note: Cut-off frequency (fc) at BOOST=MID is approximate value.
C [µF]
100
100
47
47
HP-AMP
AK4569
Figure 16. External Circuit Example of Headphone
BOOST=OFF
fc [Hz]
148.6
105.8
69.8
49.7
R
BOOST=MID
- 21 -
fc [Hz]
C
65
27
43
20
Headphone
16Ω
Output Power [mW]
8.7
4.4
[AK4569]
2005/07