
April 1993
7
Philips Semiconductors
Product specification
Digital multistandard colour decoder with
SCART interface (DMSD2-SCART)
SAA7151B
handbook, full pagewidth
TDA8446
VIDEO
SWITCH AND
MATRIX
S
(
TDA8540
VIDEO
SWITCH
C
Y
Y/C
CVBS
R
G
B
sync
FS
CVBS/Y/sync
chroma
BP
C
R
G
B
sync
LP
LP
+
U
V
TDA8709A
8-bit ADC
and multiplexer
(CHROMINANCE)
TDA8708A
8-bit ADC
(LUMINANCE)
CSO
Y
HCL
GPSW1
GPSW2
FS
*
CPISW1
SW2
FSO
FSI
from SCART interface SAA7151B
GA GB
ADI
AO
AO
CPO
t
CVBS(7-0)
D
D
CUV(7-0)
CPI
CLS CLP
MUXC
GPSW1
+5 V
CLK
CLK
MEH305-3
I2
(select)
FE
ADI
*
fast switching of Y signal for insertion
(UV are switched inside SAA7151B)
clamping
C
V2
V0
sync
LP
CVBS/Y
HCT4053
MULTIPLEXER
U/V
S0 1
Fig.3 System configuration, RGB fast switch interface included (SCART).
The multipliers operate as a quadrature demodulator for all
PAL and NTSC signals; it operates as a frequency
down-mixer for SECAM signals.
The two multiplier output signals are converted to a serial
UV data stream and applied to two low-pass filter stages,
then to a gain controlled amplifier. A final multiplexed
low-pass filter achieves, together with the preceding
stages, the required bandwidth performance. The from
PAL and NTSC originated signals are applied to a
comb-filter. The signals, originated from SECAM, are fed
through a cloche filter (0 Hz centre frequency), a phase
demodulator and a differentiator to obtain
frequency-demodulated colour-difference signals.
The SECAM signals are fed after de-emphasis to a
cross-over switch, to provide the both serial-transmitted
colour-difference signals. These signals are finally fed via
the fast switch to the output formatter stages and to the
output interface.
Chrominance signals are output in parallel (4:2:2) on the
YUV-bus. The data rate of Y signal (pixel rate) is
13.5 MHz. UV signals have a data rate of 13.5 MHz/2 for
the 4:2.2 format (Table 2) respectively 13.5 MHz/4 for the
4:1.1 format (Table 3).
Component processing and SCART interface control
The 8-bit multiplexed colour-difference input signal (signal
CUV, Fig.1, out of matrixed RGB in Fig.3) is fed via the
input interface to a chrominance stop filter (UV signal only
can pass through; Figures 22 to 24). Here it is clamped
and fed to the offset compensation which can be enabled
or disabled via the I
2
C-bus.