SAA4963T Philips, SAA4963T Datasheet - Page 7

• Manufacturer Part Number: SAA4963T
• Description: Integrated NTSC comb filter
• Manufacturer: Philips

Philips Semiconductors
The PLL provides a master clock MCK of 6
locked to the subcarrier frequency at FSC (pin 1).
The system clock CL3 (3
divide-by-two circuit. The 180 phase shift is generated by
stopping the divide-by-two circuit for one MCK clock cycle.
The generated clock is a pseudo-line-locked clock that is
referenced to f
necessary signals H
and the field (V) sync periods.
The input signals of the control and clock processing
(CLOCK CONTROL) are:
The output signals are:
H
A built-in sync separator circuit generates the H
V
working properly with a 12 dB attenuated sync in a normal
700 mV black-to-white video input signal (see Fig.5).
C
The black level clamping of the video input signals (CVBS
and Y
The clamping level is nearly adequate to the voltage at
REFDL (pin 10). The clamp consists of a pre clamp and a
main clamp. Always the signal which is switched to the
output is clamped via the main clamp while the other signal
is pre clamped. This reduces the distortion during
switching from COMB-mode to SVHS-mode and vice
versa.
1997 Mar 03
DET
ORIZONTAL AND VERTICAL SYNC SEPARATOR
LAMP
H
V
FSC: subcarrier frequency
SVHS: SVHS control signal.
CL3: system clock (3
HSEL: line start signal for the delay line
STOPS: forces the IC via the switches S2A and S2B into
the SVHS-mode or into COMB-mode (always
asynchronous).
Integrated NTSC comb filter
DET
DET
signals from the CVBS input signal. This circuit is still
ext
: analog vertical pulse from sync separator
: analog horizontal pulse from sync separator
) is performed by the sync separator stage.
sc
. The sync separator generates the
DET
and V
f
sc
f
sc
)
) is obtained from MCK by a
DET
indicating the line (H)
f
sc
DET
, which is
and
7
Table 4 Function of pre clamp and main clamp
S
Two switches are included to bypass the comb filter signal
processing. The input video signal C
is internally biased.
For the Y
Table 5 Y
For the C
Table 6 C
CVBS
Y
LOW
HIGH
LOW
HIGH
SVHS
SVHS
IGNAL SWITCHES
ext
INPUT
O
O
YCOMB (combed luminance)
input Y
CCOMB (combed chrominance)
input C
output two signals can be selected via S2A.
O
output two signals can be selected via S2B.
O
main clamp
pre clamp
output signal
output signal
COMB-MODE
ext
ext
C
Y
S2A
O
O
OUTPUT SIGNAL
OUTPUT SIGNAL
AND
S2B
Preliminary specification
pre clamp
main clamp
ext
for the switch S2B
SVHS-MODE
SAA4963
COMB
SVHS
COMB
SVHS
MODE
MODE