
Philips Semiconductors
Preliminary specification: Version 1.0
May 1995
13
Digital Servo Processor and Compact Disc Decoder (CD7)
SAA7378GP
The first flag bit, F1, is the absolute time sync signal; the FIFO-passed subcode-sync and relates the position of the subcode-
sync to the audio data (DAC output). The output flags can be made available at bit 4 of the EBU data format (LSB of the 24-
bit data word), if selected by register A.
7.7
Audio Functions
7.7.1
When pre-emphasis is detected in the Q-channel subcode, the digital filter automatically includes a deemphasis filter section.
When deemphasis is not required, a phase compensation filter section controls the phase of the digital oversampling filter
to
≤ ±
1
°
within the band 0 - 16 kHz. With deemphasis the filter is not phase linear.
If the deemphasis signal is set to be available at V5, selected via register D, then the deemphasis filter is bypassed.
Deemphasis and Phase Linearity
7.7.2
The SAA7378 contains a 2 - 4 times oversampling IIR filter. The filter specification of the 4 x oversampling filter is given in
the table below.
Digital Oversampling Filter
These attenuations do not include the sample and hold at the external DAC output or the DAC post filter. When using the
oversampling filter, the output level is scaled -0.5 dB down, to avoid overflow on full scale sine wave inputs (0 - 20 kHz).
F1
F2
F3
F4
F5
F6
F7
F8
MEANING
0
x
x
x
x
x
x
x
No Absolute Time sync
1
x
x
x
x
x
x
x
Absolute Time sync
x
0
0
x
x
x
x
x
C1 frame contained no errors
x
0
1
x
x
x
x
x
C1 frame contained 1 error
x
1
0
x
x
x
x
x
C1 frame contained 2 errors
x
1
1
x
x
x
x
x
C1 frame uncorrectable
x
x
x
0
0
x
x
0
C2 frame contained no errors
x
x
x
0
0
x
x
1
C2 frame contained 1 error
x
x
x
0
1
x
x
0
C2 frame contained 2 errors
x
x
x
0
1
x
x
1
C2 frame contained 3 error
x
x
x
1
0
x
x
0
C2 frame contained 4 errors
x
x
x
1
1
x
x
1
C2 frame uncorrectable
x
x
x
x
x
0
0
x
No interpolations
x
x
x
x
x
0
1
x
At least one 1-sample interpolation
x
x
x
x
x
1
0
x
At least one hold and no interpolations
x
x
x
x
x
1
1
x
At least one hold and one 1-sample interpolation
PASSBAND
ATTENUATION
0 - 19 kHz
≤
0.001 dB
≤
0.03 dB
19 - 20 kHz
STOPBAND
ATTENUATION
24.0 kHz
≥
25 dB
≥
38 dB
≥
40 dB
≥
50 dB
≥
31 dB
≥
35 dB
≥
40 dB
24 - 27 kHz
27 - 35 kHz
35 - 64 kHz
64 - 68 kHz
68 kHz
69 - 88 kHz