ASAHI KASEI [AK4114]
MS0098-E-04 2004/03
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OPERATION OVERVIEW
Non-PCM (AC-3, MPEG, etc.) and DTS-CD Bitstream Detection
The AK4114 has a Non-PCM steam auto-detection function. When the 32bit mode Non-PCM preamble based on Dolby
“AC-3 Data Stream in IEC60958 Interface” is detected, the AUTO bit goes “1”. The 96bit sync code consists of 0x0000,
0x0000, 0x0000, 0x0000, 0xF872 and 0x4E1F. Detection of this pattern will set the AUTO “1”. Once the AUTO is set
“1”, it will remain “1” until 4096 frames pass through the chip without additional sync pattern being detected. When
those preambles are detected, the burst preambles Pc and Pd that follow those sync codes are stored to registers. The
AK4114 also has the DTS-CD bitstream auto-detection function. When AK4114 detects DTS-CD bitstreams, DTSCD bit
goes to “1”. When the next sync code does not come within 4096 flames, DTSCD bit goes to “0” until when AK4114
detects the stream again.
192kHz Clock Recovery
On chip low jitter PLL has a wide lock range with 32kHz to 192kHz and the lock time is less than 20ms. The AK4114
has the sampling frequency detect function. By either the clock comparison against X’tal oscillator or using the channel
status, AK4114 detects the sampling frequency (32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz and 192kHz). The
PLL loses lock when the received sync interval is incorrect.
Master Clock
The AK4114 has two clock outputs, MCKO1 and MCKO2. These clocks are derived from either the recovered clock or
from the X'tal oscillator. The frequencies of the master clock outputs (MCKO1 and MCKO2) are set by OCKS0 and
OCKS1 as shown in Table 1. The 512fs clock will not output when 96kHz and 192kHz. The 256fs clock will not output
when 192kHz.
No. OCKS1 OCKS0 MCKO1 MCKO2 X’tal fs (max)
0 0 0 256fs 256fs 256fs 96 kHz
1 0 1 256fs 128fs 256fs 96 kHz
2 1 0 512fs 256fs 512fs 48 kHz
3 1 1 128fs 64fs 128fs 192 kHz
Default
Table 1. Master Clock Frequency Select (Stereo mode)
Clock Operation Mode
The CM0/CM1 pins (or bits) select the clock source and the data source of SDTO. In Mode 2, the clock source is
switched from PLL to X'tal when PLL goes unlock state. In Mode3, the clock source is fixed to X'tal, but PLL is also
operating and the recovered data such as C bits can be monitored. For Mode2 and 3, it is recommended that the
frequency of X’tal is different from the recovered frequency from PLL.
Mode CM1 CM0 UNLOCK PLL X'tal Clock source SDTO
0 0 0 - ON ON(Note) PLL RX
1 0 1 - OFF ON X'tal DAUX
0 ON ON PLL RX
2 1 0
1 ON ON X'tal DAUX
3 1 1 - ON ON X'tal DAUX
Default
ON: Oscillation (Power-up), OFF: STOP (Power-down)
Note : When the X’tal is not used as clock comparison for fs detection (i.e. XTL1,0= “1,1”), the X’tal is off.
Table 2. Clock Operation Mode select
