參數(shù)資料
型號: LC78622NE
廠商: Sanyo Electric Co.,Ltd.
英文描述: Compact Disc Player DSP(用于CD播放器的8位DSP)
中文描述: 光碟機的DSP(用于光盤播放器的8位數(shù)字信號處理器)
文件頁數(shù): 24/31頁
文件大小: 338K
代理商: LC78622NE
No. 6015-24/31
LC78622NE
24. Circuit Block Operating Descriptions
RAM address control
The LC78622NE incorporates an 8-bit
×
2k-word RAM on chip. This RAM has an EFM demodulated data jitter
handling capacity of ±4 frames implemented using address control. The LC78622NE continuously checks the
remaining buffer capacity and controls the data write address to fall in the center of the buffer capacity by making fine
adjustments to the frequency divisor in the PCK side of the CLV servo circuit. If the ±4 frame buffer capacity is
exceeded, the LC78622NE forcibly sets the write address to the ±0 position. However, since the errors that occur due
to this operation cannot be handled with error flag processing, the IC applies muting to the output for a 128 frame
period.
C1 and C2 Error Correction
The LC78622NE writes EFM demodulated data to internal RAM to compensate for jitter and then performs the
following processing with uniform timing based on the crystal oscillator clock. First, the LC78622NE performs C1
error checking and correction in the C1 block, determines the C1 flags, and writes the C1 flag register. Next, the
LC78622NE performs C2 error checking and correction in the C2 block, determines the C2 flags, and writes data
to internal RAM.
Note: 1. If the positions of the errors determined by the C2 check agree with those specified by the C1 flags, the correction is performed and the flags
are cleared. However, if the number of C1 flags is 7 or higher, C2 correction may fail. In this case correction is not performed and the C1 flags
are taken as the C2 flags without change. Error correction is not possible if one error position agrees and the other does not. Furthermore, if
the number of C1 flags is 5 or under, the C1 check result can be seen as unreliable. Accordingly, the flags will be set in this case. Cases
where the number of C1 flags is 6 or more are handled in the same way, and the C1 flags are taken as the C2 flags without change. When
there is not even one agreement between the error positions, error correction is, of course, impossible. Here, if the number of C1 flags was 2
or under, data that was seen as correct after C1 correction is now seen as incorrect data. The flags are set in this case. In other cases, the C1
flags are taken as the C2 flags without change.
2. When data is determined to have three or more errors and be uncorrectable, correction is, of course, impossible. Here, if the number of C1
flags was 2 or under, data that was seen as correct after C1 correction is now seen as incorrect data. The flags are set in this case. In other
Position
Division ratio or processing
–4 or less
Force to ±0
–3
589
–2
589
Increase ratio
–1
589
±0
588
Standard ratio
+1
587
+2
587
Decrease ratio
+3
587
+4 or more
Force to ±0
C1 flag
Error correction and flag processing
No errors
No correction required · Flag reset
1 error
Correction · Flag reset
2 errors
Correction · Flag set
3 errors or more
Correction not possible · Flag set
C2 flag
Error correction and flag processing
No errors
No correction required · Flag reset
1 error
Correction · Flag reset
2 errors
Depends on C1 flags
*
1
3 errors or more
Depends on C1 flags
*
2
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相關代理商/技術參數(shù)
參數(shù)描述
LC78624E 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:Compact Disc Player DSP
LC78625 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:Compact Disc Player DSP
LC78625E 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:Compact Disc Player DSP
LC78626 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:DSP for Compact Disk Players
LC78626E 制造商:SANYO 制造商全稱:Sanyo Semicon Device 功能描述:DSP for Compact Disk Players