ak4555 AKM Semiconductor, Inc., ak4555 Datasheet - Page 9

• Manufacturer Part Number: ak4555
• Description: Low Power & Small Package 20bit ?? Codec
• Manufacturer: AKM Semiconductor, Inc.

16.0kHz
32.0kHz
44.1kHz
48.0kHz
8.0kHz
ASAHI KASEI
The AK4555 can be input MCLK=256fs, 384fs, 512fs, 768fs or 1024fs (fs is equal to or lower than 25kHz when MCLK
is 1024fs). The input clock applied to the MCLK pin as internal master clock is divided into 256fs automatically. When
MCLK is 1024fs, oversampling rate of D/A converter is automatically changed from 128fs to 256fs. The relationship
between the external clock applied to the MCLK input and the desired sample rate is defined in Table 1. The LRCK clock
input should be synchronized with MCLK. The phase between these clocks does not matter. *fs is sampling frequency.
When the synchronization is out of phase by changing the clock frequencies during normal operation, the AK4555 may
occur click noise. In case of DAC, click noise is avoided by setting the inputs to “0”.
All external clocks(MCLK, SCLK and LRCK) must be present unless PWADN=PWDAN= “L”. If these clocks are not
provided, the AK4555 may draw excess current and may not possibly operate properly because the device utilizes
dynamic refreshed logic internally.
For low sampling rates, outband noise causes S/N of DAC to degrade. S/N is improved by setting MCLK to 1024fs. Table
2 shows S/N of DAC output.
MS0363-E-01
fs
System Clock Input
11.2896MHz
12.2880MHz
2.0480MHz
4.0960MHz
8.1920MHz
256fs
8kHz ∼ 50kHz
8kHz ∼ 25kHz
fs
Table 2. Relationship among fs, MCLK frequency and S/N of DAC
12.2880MHz
16.9344MHz
18.4320MHz
3.0720MHz
6.1440MHz
384fs
256fs/384fs/512fs/768fs
16.3840MHz
22.5792MHz
24.5760MHz
Table 1. System Clock Example
4.0960MHz
8.1920MHz
OPERATION OVERVIEW
MCLK
512fs
MCLK
1024fs
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12.2880MHz
24.5760MHz
33.8688MHz
36.8640MHz
6.1440MHz
768fs
S/N(fs=8kHz, A-weighted)
16.3840MHz
8.1920MHz
1024fs
N/A
N/A
N/A
84dB
90dB
0.2560MHz
0.5120MHz
1.0240MHz
1.4112MHz
1.5360MHz
32fs
SCLK
[AK4555]
0.512MHz
1.024MHz
2.048MHz
2.822MHz
3.072MHz
2005/08
64fs