AK4554 Datasheet, PDF (10/17 Pages) Asahi Kasei Microsystems – Low Power & Small Package 16bit ΔΣ CODEC

ASAHI KASEI
[AK4554]
„ Audio Serial Interface Format
Data is shifted in/out the SDTI/SDTO pins using SCLK and LRCK inputs. The data is MSB first, 2’s compliment.
LRCK
SCLK(i)
(32fs)
SDTI(i)
SDTO(o)
SCLK(i)
(64fs)
01
15 14
01
SDTO(o) _{15 14}
10 11 12 13 14 15 0 1
6 5 4 3 2 1 0 15 14
14 15 16 17
31 0 1
210
15 14
10 11 12 13 14 15 0 1
6 5 4 3 2 1 0 15 14
14 15 16 17
31 0 1
210
15 14
SDTI(i)
Don’t care
15 14
0 Don’t care
15 14
0
15:MSB, 0:LSB
Lch Data
Rch Data
Figure 4. Audio Interface Timing
„ De-emphasis filter
The DAC of AK4554 includes the digital de-emphasis filter (tc=50/15µs) by IIR filter. This filter corresponds to three
frequencies (32kHz, 44.1kHz and 48kHz). The de-emphasis filter selected by DEM0 and DEM1 pins is enabled for input
audio data. The de-emphasis is also disabled at DEM1 pin = “L” and DEM0 pin = “H”.
DEM1 pin DEM0 pin
Mode
L
L
44.1kHz
L
H
OFF
H
L
48kHz
H
H
32kHz
Table 3. De-emphasis filter control
„ Digital High Pass Filter
The AK4554 has a Digital High Pass Filter (HPF) for DC-offset cancel. The cut-off frequency of the HPF is 3.4Hz at
fs=44.1kHz and the frequency response at 20Hz is −0.12dB. It also scales with the sampling frequency (fs).
MS0325-E-01
- 10 -
2005/08